United States
Environmental Protection
Agency
EPA 402-F-13053 I December 2013 I www.epa.gov/iaq/moisture
            Moisture Control
            Guidance for  Building
            Design, Construction
            and Maintenance
                            Indoor Air Quality (IAQ)

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Moisture Control Guidance for Building Design, Construction and Maintenance
U.S. Environmental Protection Agency
December 2013
www.epa.gov/iaq/moisture

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Foreword: How to Use this Guidance	v

Acknowledgements	vi

Chapter 1
  Moisture Control In Buildings	 1
    Introduction	 1
    Health Implications of Dampness in Buildings	 1
    Moisture Damage in Buildings	2
    Moisture Problems are Expensive	7
    How Water Causes Problems in Buildings	7
    Moisture Control Principles for Design	8
    Moisture Control Principle #1: Control Liquid Water	8
    Moisture Control Principle #2: Manage Condensation	 14
    Moisture Control Principle #3: Use Moisture-Tolerant Materials	 19
  The Basics Of Water Behavior	24

Chapter 2
  Designing for Moisture Control	26
    Introduction	26
    Designing Effective  Moisture Controls	26
    Building Commissioning	26
    Who Should Read this Chapter	27
    Site Drainage	28
    Foundations	32
    Walls	38
    Roof And Ceiling Assemblies	45
    Plumbing Systems	54
    HVAC  Systems	57

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Chapter 3
  Constructing to Prevent Moisture Problems	67
    Introduction	67
    Pre-Construction Planning	71
    Site Drainage Construction	74
    Foundation Construction	76
    Wall Construction	78
    Roof and Ceiling Assembly Construction	80
    Plumbing System Installation	82
    HVAC System Installation	84

Chapter 4
  Operating and  Maintaining Moisture-Controlled Environments	87
    Introduction	87
    Site Drainage Maintenance	90
    Foundation Maintenance	92
    Wall Maintenance	93
    Roof and Ceiling Assembly Maintenance	95
    Plumbing System Operation and Maintenance	98
    HVAC System Operation  and Maintenance	99

Appendix A -  The "Pen Test"	A-I

Appendix B -  Roof Inspection Checklist	B-I

Appendix C -  Testing Moisture During Construction	c-i

Appendix D -  Air Pressure Mapping	D-I

Appendix E -  HVAC Inspection Checklist	E-I

Appendix F - Site Drainage  Maintenance	F-I

Appendix G -  Dampness  & Mold Evaluation	G-I

Glossary	H-I

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   Foreword: How to  Use this Guidance
This document was developed by the U.S.
Environmental Protection Agency, Indoor
Environments Division. It provides practical guidance
on how to control moisture  in buildings.1 It is not a
textbook, code or standard.

Chapter 1 focuses on principles of moisture control:
how water moves into and within a building and
why the movement of water should be controlled or
managed. Chapters 2, 3 and 4 provide profession-
specific guidance for the design, construction and
maintenance phases of a building's  life. To illustrate
how core concepts and principles relate to each stage
of a building's life, each guidance chapter contains
hyperlinks to relevant principles described in Chapter
1 and other related material throughout the text. Each
guidance chapter also includes methods for verifying
the appropriate implementation of the moisture
control recommendations and a reference section
that identifies additional related  resources for readers
interested in more detailed  information.
 Who Should Read this Guide

This guide can be used by anyone who designs,
builds, operates or maintains buildings and heating,
ventilating and air conditioning (HVAC) equipment. It
was developed specifically for:
• Professionals who design buildings and produce
  drawings,  specifications and contracts for
  construction or renovation.
• Professionals who erect buildings from the
  construction documents.
• Professionals who operate and maintain  buildings,
  conducting preventive  maintenance, inspecting the
  landscape, building interior and exterior equipment
  and finishes and performing maintenance and
  repairs.
'NOTE: This document does not address flood water control. For information about managing flood water, see http://www.epa.gov/naturalevents/flooding.html or http://www.epa.
gov/naturalevents/hurricanes/. Accessed on November 6, 2013.

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   Acknowledgements
The United States Environmental Protection Agency, Office of Radiation and Indoor Air, Indoor Environments
Division would like thank the many professionals who contributed to this document, including Terry Brennan
and Michael Clarkin  of Camroden Associates and Lew Harriman of Mason-Grant Consulting.

The Agency would also like to thank Christopher Patkowski for permission to use the photograph of water
droplets on the front and back covers.

The figures in this document came from several sources:
  • Terry Brennan provided the photographs used  in Figures 1-1 to  1-14.
  • Christopher Patkowski created Figures 1-15, 1-16 and 2-14 based on illustrations in the Whole Building
    Design Guide (www.wbdg.org), a program  of the National Institute of Building Sciences.
  • Terry Brennan drew Figure 1-17 and provided  the spreadsheets used to create Figures 1-18 and 1-19. He
    also provided the photograph for Figure 1-20.
  • Christopher Patkowski created Figure 2-1. He also created Figures 2-2 to 2-4, Figures 2-6 and 2-7, and
    Figures 2-9 to 2-12 based on illustrations provided by Joe Lstiburek of Building Science Corporation.
  • The U.S. Department of Energy provided the map in Figure 2-5.
  • Christopher Patkowski drew Figure 2-8 based  on an illustration  in a  publication of the Canadian Mortgage
    and Housing Corporation. He also drew Figure 2-13.
  • Terry Brennan drew Figures 2-15 and 2-16.
  • Lew Harriman provided Figure 2-17.
  • Terry Brennan provided Figure 4-1  and drew Figures A-l to A-3.
  • Christopher Patkowski drew Figures D-l to D-3 based on drawings by Terry Brennan.
  • Figure G-l was  provided by the National Institute of Occupational Safety and Health  (NIOSH).

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   Chapter 1: Moisture  Control  in  Buildings
 Introduction

Moisture control is fundamental to the proper
functioning of any building. Controlling moisture is
important to protect occupants from adverse health
effects and to protect the building, its mechanical
systems and its contents from physical or chemical
damage. Yet,  moisture problems are so common in
buildings,  many people consider them inevitable.

Excessive moisture accumulation  plagues buildings
throughout the United States, from tropical Hawaii
to arctic Alaska and from the hot, humid Gulf Coast
to the hot, dry Sonoran Desert. Between 1994 and
1998, the U.S. Environmental  Protection Agency
(EPA) Building Assessment Survey and Evaluation
(BASE)  study collected information about the indoor
air quality of  100  randomly selected public and
private office  buildings in the 10  U.S. climatic
regions. The BASE study found that 85 percent of the
buildings had been damaged by water at some time
and 45  percent had leaks at the time the data were
collected.2

Moisture causes problems for building owners,
maintenance  personnel and occupants. Many
common moisture problems can be traced to poor
decisions in design, construction  or maintenance. The
American Society of Heating, Refrigerating and Air
Conditioning  Engineers (ASHRAE) notes that, more
often than not, the more serious problems are caused
by decisions made by members of any of a number of
different professions.3 However, such problems can
be avoided with techniques that are based on a solid
understanding of how water behaves in buildings.

Moisture control consists of:
• Preventing  water intrusion and  condensation in
  areas of a building that must remain dry.
• Limiting the areas of a building that are routinely
  wet because of their use (e.g., bathrooms, spas,
  kitchens and janitorial closets)  and drying them out
  when they do get wet.
To be successful, moisture control does not require
everything be kept completely dry. Moisture control is
adequate as long as vulnerable materials are kept dry
enough to avoid problems. That means the building
must be designed, constructed and operated so that
vulnerable materials do not get wet. It also means
that when materials do get wet, the building needs to
be managed in such a way that the damp materials
dry out quickly.


 Health Implications of Dampness in Buildings

At the request of the  U.S. Centers for Disease Control
and Prevention (CDC), the Institute of Medicine (IOM)
of the National Academy of Sciences convened a
committee of experts to conduct a comprehensive
review of the scientific literature concerning
the relationship between damp or moldy indoor
environments and the appearance of  adverse health
effects in exposed populations. Based on their review,
the members of the Committee on Damp Indoor
Spaces and Health  concluded that the epidemiologic
evidence shows an association between exposure to
damp indoor environments and adverse health effects,
including:
•  Upper respiratory (nasal and throat) symptoms.
• Cough.
• Wheeze.
• Asthma symptoms  in sensitized persons with
  asthma.

The committee also determined that  there is limited
or suggestive evidence of  an association between
exposure to damp indoor environments and:
•  Dyspnea (shortness of breath).
•  Lower respiratory illness in otherwise healthy
  children.
• Asthma development.
2 http://www.epa.gov/iaq/base/. Accessed November 6, 2013.

3 Limiting Indoor Mold and Dampness in Buildings. 2013 (PDF) at https://www.as rirae.org/about-asrirae/position-documents. Accessed November 6, 2013.

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Details of the results of this review were published in
a 2004 report,  Damp Indoor Spaces and Health.4 It
is also important to note that immuno-compromised
individuals, such as some categories of hospital
patients, are at increased risk for fungal colonization
and opportunistic infections.5

After  the publication of the IOM  report, a study by
Lawrence Berkeley  National Laboratory concluded
that building dampness and  mold raise the risk of
a variety of respiratory and asthma-related health
effects by 30 to 50 percent.6 A companion study by
EPA and Berkeley Lab estimated that 4.6 million
cases of asthma, 21 percent of the 21.8 million cases
of asthma  in the U.S. at that time, could be attributed
to exposure to dampness and mold in homes.7
 Moisture Damage in Buildings

In addition to causing health problems, moisture
can damage building materials and components. For
example:
• Prolonged damp conditions can lead to the
  colonization of building materials and  HVAC
  systems by molds, bacteria, wood-decaying molds
  and insect pests (e.g., termites and carpenter ants).
• Chemical reactions with building  materials and
  components can cause, for example, structural
  fasteners, wiring, metal roofing and conditioning
  coils to corrode and flooring or roofing  adhesives to
  fail.
• Water-soluble  building materials (e.g.,  gypsum
  board) can return to solution.
• Wooden materials can warp,  swell or rot.
• Brick or concrete can be damaged during freeze-
  thaw cycles and  by sub-surface salt deposition.
• Paints and varnishes can be  damaged.
• The insulating value (R-value) of thermal  insulation
  can be reduced.

The following photos show some of the damage that
can result from moisture problems in buildings.
                                                Figure 1-1 Mold growing on the surface of painted gypsum board and trim.
                                                Long-term high humidity is the source of the moisture that allowed the mold
                                                growth. All of the walls experienced similar near-condensation conditions.
                                                Consequently, the mold growth is widespread rather than concentrated in a
                                                single damp area.
4 Institute of Medicine (2004) Damp Indoor Spaces and Health. http://www.iom.edu/Reports/2004/Damp-lndoor-Spaces-and-Health.aspx. Accessed November 6, 2013.

5 Institute of Medicine (2004) Damp Indoor Spaces and Health. http://www.iom.edu/Reports/2004/Damp-lndoor-Spaces-and-Health.aspx. Accessed November 6, 2013.

6 W. J. Fisk, Q. Lei-Gomez, M. J. Mendell (2007) Meta-analyses of the associations of respiratory health effects with dampness and mold in homes. Indoor Air 17(4), 284-295.
dohlO.llll /j. 1600-0668.2007.00475.x

7 D. Mudarri, W. J. Fisk (2007) Public health and economic impact of dampness and mold. Indoor Air 17 (3), 226-235. dohlO.llll /j.1600-0668.2007.00474.x

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Figure 1-2 Mold growth on painted concrete masonry. The cool masonry wall
separates a classroom from an ice rink. Humid air in the classroom provides
moisture that condenses on the painted surface of the masonry. That moisture
allows mold to grow on the paint film.
Figure 1-3 Mold growth on vinyl floor tile. Long-term high humidity provided
moisture that was absorbed into the cool vinyl tile and supported mold
growth. Also note that the high humidity caused the adhesive attaching the
tile to the floor to fail, allowing the tile to become loose.
Figure 1-4 Corrosion of galvanized fluted steel floor deck. The floor is at grade
level. The source of the water is rainwater seepage.

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                                                    Figure 1-5 Corrosion of structural steel  in a ceiling cavity in a cold climate.
                                                    The steel  extends into the exterior wall assembly. During cold weather, the
                                                    steel near the wall is chilled by cold outdoor air. The building is humidified,
                                                    and condensation from high indoor humidity provides the moisture that rusts
                                                    the cold steel.
                                                    Figure 1-6 Blistering paint on split face concrete block. Wind-driven rain
                                                    is the source of moisture contributing to the damage. Water wicks into
                                                    the concrete masonry unit (CMU) through pin holes in the paint. The sun
                                                    drives water vapor through the CMU. The assembly cannot dry to the interior
                                                    because low-vapor-permeability foam board, taped at the joints, insulates the
                                                    interior surface of the wall. The wall remains saturated throughout the spring,
                                                    summer and fall. The same paint on areas of the wall sheltered from sun and
                                                    rain shows no damage.


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Figure 1-7 Condensation behind vinyl wallpaper in a warm, humid climate.
Condensation and mold growth occurs behind the vinyl wallpaper on both
exterior and  interior walls.  Air leaks in the return plenum of the air handler
depressurizes the interior and exterior wall cavities. Warm, humid exterior air
is drawn from outside through air leaks in a heavy masonry wall.
Figure 1-8 Rainwater leaks in a rooftop parapet wall result in damaged plaster
and peeling paint. Rainwater is drawn into this brick assembly by capillary
action, and the moisture is aided in  its downward migration  by gravity. The
peeling paint contains lead and results in an environmental  hazard as well as
physical damage to the plaster.
Figure 1-9 Interior plaster damaged by rain seeping around a window in a
brick building. The inside of the exterior wall is insulated with closed-cell
spray foam. Consequently, the wall cannot dry to the interior, so it retains
excessive amounts of moisture. At the point where the plaster on the window
return meets the brick wall, rainwater wicks into the plaster causing the
damage seen  in this photo.

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                                                     Figure 1-10 Further rain damage to interior plaster. At another location on an
                                                     office window in the building shown in Figure 1-8, rain seepage turns gypsum
                                                     board joint compound to a fluid, causing the gypsum to bubble and lift.
                                                     Figure 1-11 Gypsum board on the lower edge of a basement wall dissolved by
                                                     seasonal flood waters. The water table is just below the basement floor during
                                                     dry weather and rises several inches above the floor during heavy spring rains.
                                                     Figure 1-12 Hardwood gymnasium floor warped by moisture in the cavity
                                                     below it. Water rises through the concrete sub-floor. The source of the
                                                     moisture is rainwater that has not been drained away from the foundation of
                                                     the building.

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                                              Figure 1-13 Tile adhesive that failed to cure because of water in the concrete
                                              and high pH. The tile can be removed by hand. The floor is a concrete slab-
                                              on-grade. The water visible in the photo evaporates into the room after several
                                              minutes. Its source may be liquid water wicking up from the sub-slab fill or
                                              water vapor migrating through the slab.
                                              Figure 1-14 Damage to bricks caused by the migration of soluble salt through
                                              them. Salts in the brick or mortar dissolve in rainwater that wicks through the
                                              brick. The water evaporates in the building's interior, and the salt left behind
                                              crystalizes and splits the surface layer off the brick, exposing its interior. This
                                              process is called sub-fluorescence.
 Moisture Problems are Expensive

Health problems and building damage due to
moisture can be extremely expensive. Berkeley Lab
estimates that the annual asthma-related medical
costs attributable to exposures to dampness and mold
total approximately $3.5 billion in the U.S.8 But many
more adverse health outcomes due to damp buildings
have been reported, each with  associated costs of
its own. And damage to the building itself is also
costly. Building owners and tenants bear a significant
proportion of these costs, including:
• Absenteeism due to illnesses such as asthma.
• Reduced productivity due to moisture-related health
  and comfort problems.
• Increased insurance risk, repair and replacement
  costs associated  with corroded structural fasteners,
  wiring and damaged moisture-sensitive materials.
• Repair and replacement costs associated with
  damaged furniture, products and supplies.
• Loss of use of building spaces after damage and
  during repairs.
• Increased insurance and  litigation  costs related to
  moisture damage claims.
 How Water Causes Problems in Buildings

Mention water damage and the first image that comes
to mind for most people is liquid water in the form
of rain,  plumbing leaks or floods. Many water leaks
are easy to detect. When it rains, water may drip
around skylights, or a crawl space may fill with water.
If a toilet supply line breaks, the floor will likely be
flooded.

On the other hand, many water-related problems
are less obvious and can be difficult to detect  or
diagnose.  For example, the adhesive that secures
flooring to a concrete slab  may not cure  properly if the
slab is damp, resulting in loose flooring and microbial
growth in the adhesive. Or,  humid indoor air may
condense  on the cool backside of vinyl wallpaper that
covers an  exterior wall, providing ideal conditions for
mold to grow. These problems are less obvious than
a leak because water is not running across the floor,
and the real damage is being done out of sight under
flooring or behind wallpaper.

Moisture problems are preventable. They do not
happen until water moves from a source into some
part of a building that should be dry. The actual
8D. Mudarri, W. J. Fisk (2007) Public health and economic impact of dampness and mold. Indoor Air 17 (3), 226-235. dohlO.llll /j. 1600-0668.2007.00474.x

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damage begins after enough moisture accumulates to
exceed the safe moisture content limit of moisture-
sensitive materials.

To diagnose or prevent a moisture problem, keep
in mind four key elements of moisture behavior in
buildings:
1. Typical symptoms of moisture problems. They
   include corrosion of metals, the growth of surface
   mold or wood-decaying molds, insect infestations,
   spalling exterior brick or concrete,  peeling paint,
   failing floor adhesives,  stained finishes and health
   symptoms.
2. Sources of moisture. Among them are rainwater,
   surface water, ground water, plumbing water,
   indoor and outdoor sources of humidity and sewer
   water.
3. Transport mechanisms. They  include liquid water
   leaking through holes,  wicking through porous
   materials, or running along the top or bottom of
   building assemblies and water vapor carried by
   warm, humid air leaking through assemblies and
   by diffusion through vapor-permeable materials.
4. Common failures of moisture control elements and
   systems. Moisture controls include site drainage,
   gutter systems, above- and below-grade drainage
   planes, effective flashing, condensate drainage
   and humidity controls.  Failures can occur during
   any phase of a building's life and may include
   poor site selection or design,  poor material or
   equipment selection, improper installation or
   sequence of building materials and equipment,
   insufficient coordination between trades during
   construction  and insufficient or improper
   maintenance of materials  or equipment.


 Moisture Control Principles for Design

To control moisture for long building life and good
indoor  air quality, follow these three  principles:
1. Control liquid water.
2. Prevent excessive indoor humidity and water vapor
   migration by air flow and diffusion in order to limit
   condensation and moisture absorption into cool
   materials  and surfaces.
3. Select moisture-resistant materials for unavoidably
   wet locations.

Armed  with an elementary understanding of these
principles, readers will be  prepared to  control
moisture and  prevent the vast majority of moisture
problems that are common in buildings.
 Moisture Control Principle #1:
 Control Liquid Water

The first principle of moisture control is to keep liquid
water out of the building. Sheltering occupants from
water is a  primary purpose of  building assemblies
including roofs, walls and foundations. Among the
sources of water from outside a building are:
• Rain and melting snow, ice or frost.
• Groundwater and surface runoff.
• Water brought into the building by  plumbing.
• Wet materials enclosed in building assemblies
  during construction.

Problem: Building Assemblies and Materials Get Wet

Moisture problems are common.  By their very nature,
buildings and the construction process are almost
certain to encounter moisture problems that could
lead to poor indoor air quality and other negative
impacts. The  most common liquid water problems
include:
• Rain and snow get inside. Rainwater,  surface water
  and ground water, including snowmelt, may enter
  a building through leaks in  roofs, walls, windows,
  doors or foundations. In most climates,  rain is the
  largest source of water in buildings. Rainwater
  intrusion can cause great damage to the building
  itself and to its contents.
• Plumbing leaks. We intentionally bring water into
  buildings for cleaning, bathing and cooking, and
  we intentionally drain wastewater out of buildings.
  Any water brought in and drained out is contained
  in pipes, vessels and fixtures that can tolerate
  being wet all or most of the time. However, leaks in
  plumbing supply lines, drain lines,  sinks, showers
  and tubs may cause problems.  Although model
  plumbing codes require both the supply side and
  drain/vent side of plumbing systems to be tested for
  leaks, these tests are sometimes performed poorly
  or not at all. Large plumbing leaks  are immediately
  obvious,  but small leaks inside walls and ceiling
  cavities  may continue unnoticed for some time.
• Water during construction causes problems.
  Some materials are installed wet because they
  were exposed to rain  or plumbing leaks  during
  construction. Wet concrete  masonry units (CMUs),
  poured or pre-cast concrete, lumber and the
  exposed earth of a crawl space floor have all been
  sources  of problems in new buildings.

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• Some materials are installed wet because water is
  part of the process. Poured concrete, floor levelers,
  wet-spray insulation and water-based finishes all
  contain water. Porous materials that appear dry may
  contain enough water to cause problems if they
  come in contact with moisture-sensitive materials
  or if they humidify a cavity after they are enclosed.
  Flooring, wall coverings and coatings will fail  if they
  are applied before surfaces are dry enough. Water
  from these materials may indirectly cause problems
  by raising the humidity indoors during a building's
  first year of use, leading to condensation problems.

Solution: Control Liquid Water Movement

Effectively controlling liquid water intrusion requires
all of the following:
• Drain rain, irrigation water and snowmelt away
  from the building. The first step in water control
  is to locate the building in dry or well-drained soil
  and use or change the landscape to divert water
  away from the structure. In other words, drain the
  site. This includes sloping the grade away from
  the building to divert surface water and keep
  subsurface water away from the foundation below
  grade. After the site is prepared to effectively drain
  water away from the building, the building needs
  a storm water runoff system to divert rain from the
  roof into the site drainage system.
• Keep  rain and irrigation water from leaking into the
  walls and roof. Leaking rainwater can cause great
  damage to a building and to the materials  inside.
  In successful systems, rainwater that falls on  the
  building is controlled  by:
  •  Exterior cladding, roofing and storm-water
     management systems to intercept most of the
     rain and drain it away from the  building.
  •  Capillary breaks, which  keep rainwater from
     wicking through porous building materials or
     through cracks between materials.  A capillary
     break is either an air gap between adjacent
     layers or a material such as rubber sheeting that
     does not absorb or pass liquid water. A few rain
     control systems consist of a single  moisture-
     impermeable material, sealed at the seams, that
     both intercepts rainwater and provides a capillary
     break. Membrane roofing and some glass panel
     claddings for walls work in this  way.
• Keep water from wicking into the building by  using
  capillary breaks  in the building enclosure.  Moisture
  migration by capillary action can be interrupted
  using an air space or water-impermeable material.
                             www.epa.gov/iaq/moisture
• Prevent plumbing leaks by locating plumbing lines
  and components where they are easy to inspect and
  repair, are unlikely to freeze, and are not in contact
  with porous cavity  insulation.
• Avoid enclosing wet materials in new construction
  by protecting moisture-sensitive and porous
  materials during transport and on-site storage and
  by drying wet materials before they are enclosed
  inside building assemblies or covered  by finish
  materials.

Drained Roofing and Wall Cladding
Roofing and cladding systems are frequently backed
by an air gap and a moisture-resistant material that
forms the drainage plane.  Most of the water that
seeps, wicks or  is blown past the cladding will  drain
out of the assembly. The drainage plane prevents any
water that might bridge the air gap from wetting the
inner portions of the  assembly. Some examples are:
• Roofs. Asphalt or wooden shingles, metal panels
  and elastomeric  membranes are common outer
  layers for roofs.
• Walls. Wooden and vinyl siding, stucco, concrete
  panels, brick,  concrete masonry units  and  stone
  veneers are common outer layers for walls.
• Drainage planes. Building felt, tar paper and water-
  resistant barriers are commonly used as drainage
  planes beneath roofing and wall cladding systems.
  Single- and multi-ply roofing combine the drainage
  plane with the outer layers of the roof—there is no
  inner drainage plane material.

Figure 1-15 illustrates the concept of a drained
wall assembly. Although the cladding intercepts
most of the rainwater, some  liquid will seep inward.
The air gap acts as a capillary break, and seepage
cannot jump that gap. Instead, seepage  runs down
the back of the  cladding until it is drained out by
the flashing. Some of the seepage may run to the
drainage plane along materials that bridge the  gap,
for example, mortar droppings or cladding fasteners.
The impermeable surface of the drainage plane keeps
water out of the  backup sheathing, CMU or concrete,
protecting the inner wall. Water flows down the
drainage plane and over the flashing, which diverts it
back outside.

Some roofing or siding materials absorb water (e.g.,
wooden shingles or siding, fiber cement siding,
traditional stucco and masonry veneers), while
others do not (e.g., roofing membranes, vinyl siding
and metal or glass  panels). Historically, the porous

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Figure 1-15 Drained Wall Assembly
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materials were backed by an air gap. Examples
include wooden shingles on skip sheathing, masonry
veneers and heavy masonry walls with 1- to 2-inch
cavities separating brick walls and beveled siding
installed shingle style. The air gap between the
siding and the interior of the wall enables wet porous
materials to dry out to either the outdoor air or into
the air gap.

In either case, the drainage plane must be watertight
at all joints and penetrations. Table 1-1 lists
penetrations commonly found  in roofs and walls and
presents ways to maintain the watertight integrity of
the drainage plane. This list is not comprehensive.
Any and all penetrations through  roofing and exterior
cladding must be detailed to prevent rainwater
intrusion.

Windows, curtain walls and storefronts are all used
in wall assemblies and are  among the more complex
penetrations to detail. Typically, standard  details for
window head, jamb and sill flashing are provided
by the manufacturers of these components. Figure
1-16 illustrates a method of providing pan sill and
jamb flashings for walls constructed with an exterior
insulation and finish system (EIFS). Note that the
sill flashing protects the wall assembly from seepage
at the corners of windows and at the joints between
windows. Dams on the sides and back of the sill
pan flashing stop any seepage from running into the
building or into the wall beneath the window.

Foundations
The building foundation must be detailed to protect
the building from rainwater. The above-grade portions
of a foundation are often masonry or concrete. Much
of the rainwater that wets the above-grade wall simply
drains off the surface to the soil below. Masonry
walls are often protected below grade using Portland
cement-based capillary breaks (e.g., traditional
parging or proprietary coatings). Concrete walls may
be treated with additives that provide an  integral
capillary break or may be so massive that absorbed
water is more likely to be safely stored in the wall—
drying out between storms—than to wick through to
the interior.

Landscape surfaces immediately surrounding the
foundation perform the same function for the walls
below grade as the  roofing and cladding in the walls
above grade: they intercept rain and drain it away
from the building.

The damp-proof or waterproof coatings on below-grade
walls serve the same purpose as the drainage plane
in the above-grade walls. These coatings  provide
a capillary  break that excludes the rainwater that
saturates the surrounding fill. An additional capillary
break is formed by free-draining gravel or geotechnical
drainage mats placed against the below-grade walls.
These materials provide an air gap that allows water
to drain freely down the foundation wall.

At the bottom of the below-grade wall, a footing
drain system carries rainwater and ground water away
from the footing and the floor slab.  Paint formulated
for use on concrete can be applied to the topside
of the footing to provide a capillary break between
the damp footing and the  foundation wall. A layer
of clean coarse gravel, with  no fines, can provide an
air-gap-style capillary break between the earth and the
concrete floor slab. Plastic film beneath the floor slab
provides a vapor barrier as well as a capillary break
beneath the slab. These drainage layers and the vapor
barriers beneath foundation slabs are often required
by building codes.
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                                                                                   www.epa.gov/iaq/moisture
 Table 1-1 Maintaining Drainage Plane Water-Tightness in Roofs and Walls
 Penetrations Commonly Found in Roofs   How to Maintain Drainage Plane Water-Tightness
 Joints between pieces of roofing

 Roof edges

 Roof intersections with adjoining, taller
 walls
 Skylights and roof hatches

 Chimneys

 Air handlers and exhaust fans

 Plumbing vents
Shingling or sealing provides continuity

Overhangs, copings and drip edges provide capillary breaks

Through-flashing provides continuity where a lower story roof
intersects the wall  of the higher level and where any roof meets a
dormer wall. Flashing and counter-flashing of veneers and  low-slope
roof membranes keep water out of joints between  materials

Flashing, curbs and counter-flashing provide continuity

Flashing, crickets and counter-flashing provide continuity

Flashing, curbs and counter-flashing provide continuity

Flashing and counter-flashing provide  continuity
 Penetrations Commonly Found in Walls   How to Maintain Drainage Plane Water-Tightness
 Windows


 Doors


 Outdoor air intakes


 Exhaust outlets and fans


 Fasteners

 Utility entrances


The "Pen Test"
Head flashing, jamb flashing and panned sill flashing provide
continuity

Head flashing, jamb flashing and panned sill flashing provide
continuity

Head flashing, jamb flashing and panned sill flashing provide
continuity

Head flashing, jamb flashing and panned sill flashing provide
continuity

Sealants provide continuity

Sealants provide continuity
The waterproof layers of the walls, roof and foundation
must form a continuous, six-sided box with no gaps,
no cracks and no holes. It is difficult to achieve this
degree of integrity, especially at the long edges where
the walls meet the roof and the foundation. The
pen test  is used before the architectural design  is
complete to help make sure these continuous water
barriers,  when installed according to the design, will
not leak.

When rainwater control has been well designed, it
should be possible to trace the waterproof layers that
form a capillary break around a sectional view of the
building  without lifting pen from paper. This simple
test can be performed not only for the rainwater
control, but  also for the thermal insulation layer and
the air barrier. The methods for all three are outlined
in Appendix A and are  part of the requirements
              for documenting compliance with the guidance in
              Chapters 2, 3 and 4.

              Figure 1-17 illustrates tracing the capillary break in a
              sample section. Starting at the center of the roof:
              • The roofing membrane  is the first line of defense,
                protecting the water-sensitive inner materials from
                rain and snowmelt.
              • Tracing the roofing membrane from the center
                of the roof to the edge of the roof, the roofing
                membrane flashes beneath a metal coping, which
                in turn flashes to a metal fascia.
              • The fascia forms a drip edge, channeling water
                away from the cladding.
              • An air gap between  the drip edge and the brick
                veneer forms a capillary break, protecting the
                materials beneath the coping from rainwater
                wicking into them.
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Figure 1-16 Pan Sill and Jamb Flashings for EIFS Walls
                 Insulated metal frame wall
                 Closure strip flashes to drain
                 plane/ air barrier
                 Base coat

                 Top coal


                 Flashing tape
                 Sub-sill flashing with up-turned
                 interior flashing leg and fully
                 sealed end-dams
                 Self-adhered membrane
                 window flashing
                 Exterior gypsum sheathing
                 Wall drain plane - continuous
                 drain plane/air barrier
                 Drained EIFS
  Behind the brick veneer, air gap and foam board, a
  water-resistant barrier (WRB) applied to the gypsum
  sheathing forms a  capillary break between the
  damp brick and the inner wall assembly.
  The WRB laps over the vertical leg of a head
  flashing,  protecting the window from rainwater with
  a drip edge and an air gap.
  The window frame, sash  and glazing form a
  capillary break system that sits in a pan sill flashing
  at the bottom of the window.
  The pan sill flashing forms a capillary break
  protecting the wall beneath from seepage through
  the window system.
  The pan sill flashing shingles over the WRB in the
  wall beneath, which shingles over a flashing that
  protects the bottom of the wall system.
• A polyethylene foam sill seal makes a capillary
  break between the foundation and the bottom
  of the framed wall,  connecting with an inch of
  extruded polystyrene insulation that makes a
  capillary break between the top of the foundation
  wall and the edge of the floor slab. Polyethylene
  film immediately beneath the slab provides the
  code-required water vapor retarder and forms a
  capillary break between the bottom of the slab and
  the fill below.  NOTE: If the bed of fill  beneath the
  slab consists of crushed stone greater than 1A inch
  in diameter (and  if  it contains no fines), the bed
  also forms a capillary break between the soil and
  the slab.

Note the critical role of flashing in excluding water
and in diverting water out of the building if it leaks
in. Applying the pen test to the building design shows

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                                                                                       www.epa.gov/iaq/moisture
Figure 1-17 Tracing the Capillary Break in a Sample Section
The blue line traces the elements of the capillary break in the rainwater control system for a section through a
building.
                     Facia
                     Drip edge and
                     air gap

                     Spray foam insulate
                     I-beam
        Coping
        Steel "Z" angle

        Tapered foam insulation

        Roof membrane
                     Self-adhered membrane
                     covers gypsum wall and
                     seals to flashing

                     Gypsum sheathing

                     1" foam board

                     Air gap

                     Head flashing (flashes
                     beneath self-adhered
                     membrane)

                     Pan sill flashing

                     Self-adhered membrane

                     Gypsum sheathing

                     1" foam board

                     Air gap

                     Brick wall

                     Flashing


                     Foam insulation at
                     down perimeter wall

                     Concrete foundation wal
         Gypsum foam
         boardings deck

         6" light steel stud
         w/ Rid fiberglass
         insulation

         Roof drain  --^J

         Window

         6" light steel stud
         w/R19 fiberglass
         insulation

         Polyethylene film

         Concrete slab

         Drainage layer
         (coarse aggregate with no fines)
the importance of flashing that is both well designed
and well installed. There are no certification  programs
for the proper installation of flashing; however,
the following trade associations offer educational
materials and training programs for flashing design
and installation:
• Sheet Metal and Air Conditioning Contractors'
  National Association (SMACNA), http://www.
  smacna.org.
• National Roofing Contractors Association, http://
  www.nrca.net/.
• National Concrete Masonry Association, http://www.
  ncma.org.
• Brick Industry Association, http://www.bia.org.
• Spray Polyurethane Foam Alliance, http://www.
  sprayfoam.org.

Prevent Plumbing Leaks
To avoid plumbing leaks, new plumbing systems must
be pressure tested at a stage of construction when the
plumbing lines are easily inspected and leaks can be
readily repaired. This is a code requirement in many
jurisdictions.

Supply  lines must be pressurized to design values,
and drain lines must hold standing water. Plumbing
must be designed not only to prevent initial problems,
but also to permit easy maintenance to avoid future
problems.
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Further, plumbing should be located where:
• Leaks will be noticed quickly.
• Leaking water will  not wet easily damaged
  materials.
• Water inside the plumbing will not freeze in cold
  weather.

Plumbing access panels allow critical  maintenance
over the life of the building. They should be located
anywhere concealed valves or traps will need to
be inspected for leaks or accessed  for adjustment,
maintenance or replacement.

No  matter the climate, avoid placing plumbing lines,
valves and drain lines in exterior walls and ceilings
that have porous insulation. If the  plumbing leaks,
insulation in those walls or ceilings will get wet. Once
wet, porous insulation takes a long time to dry (or may
never dry). This situation can lead  to mold growth,
corrosion of structural fasteners and needless energy
consumption. Also, in climates with cold winters, any
plumbing located in exterior walls or above ceiling
insulation is more prone to freezing and bursting.

Avoid Enclosing Wet Materials in  Building
Assemblies
Moisture-sensitive materials and equipment should
be kept dry during construction.  In particular, gypsum
board, finished woodwork,  cabinets and virtually all
mechanical equipment should be stored in a weather-
protected shelter or installed in their final, weather-
protected locations immediately upon  delivery to the
site.

If moisture-sensitive  or porous materials get wet, dry
them quickly before mold grows or physical damage
occurs. Masonry walls and concrete floor slabs, for
example, are very porous and can hold a great deal of
water. Masonry block and concrete must be thoroughly
dry before being coated or covered  by  water-sensitive
materials such as floor tile, carpeting,  paint or paper-
faced gypsum board.

Water is added to some materials during installation
(e.g., concrete, water-based coatings,  wet-spray fire-
proofing and wet-spray insulation).  These materials
must be allowed to dry naturally, or force-dried using
specialized equipment before being enclosed  in
building assemblies.  These intentionally wet materials
may not suffer from long exposure  to moisture, but
as they dry, they will  transfer their  moisture to nearby
    materials that can support mold
    dimension.
;rowth or change
    Moisture Control Principle #2:
    Manage Condensation
9 Dew point can be measured by cooling a mirrored surface until condensation just
mirror devices.
    Limit indoor condensation and make sure
    condensation dries out when and where it occurs.


    Problem: Condensation Happens—
    Keep Track of the Dew Point

    Both indoor air and outdoor air contains water vapor.
    Wherever air goes, water vapor goes. When humid
    air contacts a surface that is cold enough, the water
    vapor in the air will condense onto that cold surface.
    The  concept of the air dew-point temperature  is very
    useful in understanding when, why and how much
    condensation will occur—and how to avoid it.

    The  dew point is the temperature of the air at  which
    condensation occurs. The higher the dew point, the
    greater the risk of condensation on  cold surfaces.
    The  dew point depends on  how much water vapor the
    air contains. If the air is very dry and has few water
    molecules, the dew point is low and surfaces must be
    much cooler than the air for condensation to occur.
    If the air is very humid and contains many water
    molecules, the dew point is high and condensation
    can  occur on surfaces that are only a few degrees
    cooler than the air.9

    Consider hot weather condensation inside a building.
    Condensation can  be prevented as long as the indoor
    air dew point is  below the temperature of surfaces
    that are likely to be cold. If the dew point rises,
    moisture will begin to condense on  cold surfaces. For
    example, humid outdoor air leaking into a building in
    Miami will have a dew point above 70°F  throughout
    most of a typical year. During normal operation of
    an air-conditioned building, there are many surf aces
    that have a temperature below 70°F. For  example, a
    supply air duct carrying air at 55°F will have a surface
    temperature near 55°F. If the infiltrating outdoor air
    has  a dew point of 70°F, its moisture will condense
    on the outside of that cold  duct, and possibly  on the
    supply air diffuser.


    Dew Point vs. Relative Humidity
    When most people think of humidity, they think of
    relative humidity (RH) rather than dew point. But

gins to appear. Monitors that measure dew point directly in this way are called chilled

 14

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relative humidity is just that, a relative measurement
and not one that expresses the absolute amount of
water vapor in the air.  In simple terms, RH  is the
amount of water vapor in the air compared to the
maximum amount the air can hold at its current
temperature.10 Change the air temperature and the
relative humidity also changes, even if the absolute
amount of water vapor in the air stays the same. So
knowing only the RH of the air is not much help in
predicting condensation.

Unlike RH, the dew point does not change with
air temperature. In that sense it is an "absolute"
measurement of the amount of water vapor in
the air. When you know the dew point of the air
and the temperature of a surface, you can predict
condensation. If the dew point is aboi/ethe
temperature of the surface, water vapor will condense
onto that cold surface. If the dew point is belowthe
surface temperature, moisture will not condense. So
it is simple to predict condensation, as long as you
know the dew point of the air surrounding the surface.

To be sure, knowing the dew point is not always easy
because many humidity instruments measure and
read only air temperature and relative humidity. So
if the instrument you are using does not display the
                                                               www.epa.gov/iaq/moisture
                                 air dew point, you will need a psychrometric chart to
                                 find the dew point based on the temperature and RH
                                 of the air. A psychrometric chart graphs the physical
                                 and thermal properties of moist air.11 A simplified
                                 psychrometric chart relating the air's temperature and
                                 RH to its dew point at sea level is shown in Figure
                                 1-18. With this chart and the readings from a  low-
                                 cost monitor to measure air temperature and RH, one
                                 can determine the more useful value of air dew point
                                 in a few seconds.

                                 For example, assume an instrument shows the
                                 outdoor air is 85°F and its RH is 60 percent. Plot
                                 that point on the chart. Then, beginning at that point
                                 move horizontally to the left until your  line intersects
                                 the saturation curve (i.e., the  100 percent RH curve
                                 that forms the left edge of the chart).  From that
                                 intersection, read straight down to the  bottom  of the
                                 chart to determine the dew point. As shown in Figure
                                 1-18, the dew point of air at 85°F and 60 percent
                                 RH is 70°F. In other words, air at those conditions
                                 will begin to condense moisture when it contacts any
                                 surface that has a temperature of 70°F or below.

                                 The psychrometric chart reveals an important dynamic
                                 between surface temperature, dew point and RH.
                                 Notice that  if the RH is 90  percent, a surface only
Figure 1-18 A Simplified Psychrometric Chart Relates Air Temperature, RH and Dew Point.
                •H
                X)
                I
                ,0
                "5
                o
                E
 0.02

0.018

0.016

0.014

0012

 0.01

0.008

0.006

0,004

0.002
                                                                100%  90%   80%  70%   60%
                            45    50    55    60    65    70     75    80    85    90    95
                                                      Temperature°(F)
10The technically more accurate definition of relative humidity is the ratio of vapor pressure in the air sample compared to the vapor pressure of that air if it were completely
saturated at the same temperature, expressed as a percentage. But the definition provided above is sufficiently accurate, easier to understand and useful for managing moisture
in buildings.

11 The psychrometric chart is a powerful tool for understanding the water vapor characteristics of air and the effects of heating and cooling moist air. Its history and use are fully
explained in theASHRAE publication Understanding Psychrometrics by Donald Gatley.
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Figure 1-19 The Difference Between Room Air Temperature and the Dew Point as a Function of RH
                  45

                  40

                  35

                  30

                  25

                  20

                  15

                  10

                    5

                    0
        Room Air Temperature
            	 80 Deg F

                 70 Deg F

                 60 Deg F
                     20      40      50       60       70       80       90      100

                                            % Relative Humidity
has to be 3°F cooler than the air for condensation to
occur. It is very likely that during normal operation in
many seasons there will  be surfaces in buildings that
are 3°F colder than room temperature.

At high temperatures, high RH may also mean there is
a strong risk of condensation. Figure 1-19 shows the
relationship between RH and the number of degrees
cooler a surface must be for condensation to appear
when the RH is between 25 percent and  100 percent.
This graph provides a way to think about dew point
in terms of RH. At 50 percent RH, a surface must be
around 20°F cooler than the room air for condensation
to occur. Under ordinary circumstances, few surfaces
in a building are 20°F cooler than room air.

Causes of Condensation in Buildings
Condensation may  be the result of excessively high
dew point, unusually cold surfaces, or a combination
of the two.

The indoor dew point is a balance between the
addition and subtraction of water vapor from the air. A
building has both indoor and outdoor sources that add
water vapor, and its mechanical systems  must have
adequate dehumidification capacity to remove it, in
order to keep the dew point within reasonable limits.

Inside residential buildings, people and their
activities, especially cooking and washing of floors
and clothes, are usually the leading sources of
humidity.

In humidified commercial and institutional buildings
such as hospitals, museums and swimming pool
enclosures, indoor humidity is very high by design or
necessity.

In low-rise buildings of  all types, damp basements or
crawlspaces may add as much water vapor to the air
in a day as all the other internal sources combined.

During the cooling season, humidity  loads from
outdoor air are far larger than loads generated inside
commercial and institutional buildings. The largest
sources of humidity are the ventilation air, the
makeup air that compensates for exhaust air, and the
air that  infiltrates into the building through air leaks
in the enclosure. If the  ventilation and makeup air is
kept dry and the building is tight so that it does not
allow much leakage, the contributions from outdoor
air will be low.
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Water vapor may be removed from indoor air
by dehumidification (e.g., air conditioners or
dehumidifiers) or by ventilation air when the outdoor
air is dry. Ventilating air only dehumidifies the indoors
when the outdoor air dew point is lower than the
indoor air dew point.

Exhaust air is a special case. When an exhaust fan
rids a building of highly humid air, from showers or
cooking, for example, the indoor humidity loads are
reduced. On the other hand, if the outdoor air that
replaces that exhaust air has a dew point above the
indoor dew point, the incoming outdoor air represents
a humidity load that  must be removed by the
mechanical system.

Condensation  Problems During Cold Weather
In cold weather, condensation  is most likely to occur
on the inside of exterior walls or roof  assemblies.
The temperature of sheathing and cladding  on the
outside of the  insulation and air barrier will  be  near
the temperature of the  outdoor air. Indoor window
surfaces are often cooler than surrounding walls and
are typically the first sites of condensation during
cold weather. If the surface temperature of an indoor
wall is below the indoor dew point at a void  in the
insulation or at an  uninsulated framing member,
enough water may  accumulate to support mold
growth. If there is a hole in  the air barrier and the
building is under negative pressure at that location,
cold infiltrating air may bypass the insulation layer
and chill indoor surfaces to temperatures below the
dew point.

Condensation may  occur within an assembly. For
example, a steel beam  that passes through an exterior
wall will be much colder than the adjoining inner
surfaces of the wall because the beam conducts
heat from inside to outside  hundreds of times faster
than an  insulated portion of the wall. If the  building
is under positive pressure, the warmer, more humid
indoor air will be forced into the enclosure through
holes in the air barrier and condensation  within  the
assembly may  result.

Condensation problems within wall or roof assemblies
are hidden and may be mistaken for rainwater
or plumbing leaks.  For  example, warm air from a
humidified space, such as a swimming pool area,
may leak past the air barrier and insulation  layers
into an attic during freezing weather. The water  vapor
in the indoor air may form frost on the bottom of
the roof deck,  accumulating there until a warm day
when it melts and  leaks back through the ceiling. If
                             www.epa.gov/iaq/moisture
Figure 1-20 Condensation on Uninsulated Metal Framing
in a Cold Climate

Condensation occurs on a C-channel at the top of a parapet
wall located in a cold climate. The building is humidified and
pressurized with filtered outdoor air to maintain specified interior
conditions.
it happens to be raining the day the condensation
problem is found, it might be mistaken for a rainwater
problem.

Air pressure can be higher inside a building than
outside for two reasons. First, the upper floors of a
building are usually under positive pressure during
cold  weather due to the stack effect. Buoyant warm
air rises from the lower to the upper floors and then
flows out near the top of the building. As a result,
cold  outdoor air is  pulled into the building at its
base. During cold weather, condensation usually
occurs on the upper floors. Any gaps, cracks or holes
through the  upper floors of the enclosure receive a
constant flow of warm, humid air exiting the building.
Condensation occurs where the warm humid air leaves
the cold enclosure.

The second  reason air pressure can be higher inside
is that, to avoid  uncomfortable drafts and freezing
pipes, the mechanical ventilation system generally
brings in more air from outdoors than is exhausted
to the outside. Condensation may occur when warm,
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humid air is forced out of the building through cold
walls. In addition, portions of a building may be
pressurized by mechanical system fans if the supply
air side of the air distribution system has more air
than the return air side. For example, a room that has
two supply diffusers but no dedicated return will be
under positive pressure when the windows and doors
are closed. If the interior surfaces of the exterior walls
near that room have gaps, cracks or holes, humid
indoor air under positive pressure will be forced into
the cold exterior wall.

Condensation Problems During Hot Weather
Condensation can sometimes be a problem in hot
weather. Hot weather condensation is more common
in buildings equipped with air conditioning (AC)
systems that are very large and difficult to control and
in buildings located in climates that  have thousands
of hours of humid weather. Six factors contribute
to problems in buildings that have air conditioning
systems:
1.  Air conditioning chills all the  indoor surfaces—
    some surfaces more than others.
2.  When air conditioners do not run long enough
    to dehumidify, they cool the air in the building
    without removing moisture from the air, raising the
    indoor dew point and increasing the chances of
    condensation on cool surfaces.
3.  Supply air ducts, diffusers and refrigerant or
    chilled water lines are much colder than the room
    air.
4.  When a building's exhaust air exceeds the amount
    of its makeup air, the building will draw in
    unconditioned, moisture-laden outdoor air through
    gaps, cracks and holes in the building enclosure.
    That outdoor  air will come into contact with
    surfaces chilled by the AC systems.
5.  Sun shining on wet masonry, stucco or wood will
    raise the temperature of that material, evaporating
    some of the stored water and  "driving" a portion
    of the evaporated water further into the assembly,
    and sometimes into contact with colder indoor
    surfaces.
6.  Intentional or accidental  vapor barriers on the
    inside surfaces of exterior walls may cause
    condensation during cooling conditions.  For
    example, water vapor driven in from  outdoors may
    condense when it encounters a vinyl wall  covering
    on the cool, inside surface of an exterior wall.
   A similar dynamic occurs in below-grade walls.
   Water vapor migrating into a basement from the
   ground beneath may condense when it encounters
   a vapor barrier on the inside of a finished
   basement wall.

Solution: Control Condensation

Effective condensation control requires keeping the
dew  point below the temperature of surfaces indoors
and within building cavities. The  dew point can be
lowered by designing, installing and  maintaining
HVAC systems to control indoor humidity in both
heating and cooling mode. Building enclosures can
be designed and constructed so surface temperatures
within the assemblies are above the dew point
regardless of season.  Neither of these design elements
can succeed by itself. They must work together as a
system.

Use airtight HVAC systems to keep indoor dew points
low. To prevent condensation on indoor surfaces
during cooling mode, keep the indoor dew point
below 55°F (e.g., maximum 50 percent RH when the
indoor air temperature is 75°F). This can be done by
designing air conditioning systems that dehumidify
even when there is no need for cooling, or by using
dedicated dehumidifiers to dry the ventilation air
whenever the outdoor dew point is above 55°F. See
references below and in Chapter 2 for more details on
designing HVAC systems to manage indoor humidity.

The most important job of the air conditioning system
is to remove the large and nearly  continuous humidity
load  from the incoming ventilation and makeup air.
After that load is removed, the much smaller water
vapor loads from indoor sources may be removed by:
• Exhaust systems designed to remove water vapor
  from known sources of humidity such as showers,
  cooking areas and indoor pools.
• Ventilation with outdoor air in non-air-conditioned
  buildings.
• Air conditioning systems equipped with dedicated
  dehumidification components and controls that
  activate them when the dew point rises above 55°F.

Design building enclosures to prevent condensation.
At minimum the exterior enclosure must:
• Be made airtight by using continuous air barrier
  systems around the entire enclosure. These
                                                   18

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  systems must greatly reduce leakage of inside air
  into the exterior enclosure assemblies during cold
  weather and leakage of outdoor air into the exterior
  enclosure or interior wall, ceiling and floor cavities
  during warm weather.12 Air sealing an enclosure
  makes it easier to manage indoor-outdoor air
  pressure relationships with practical airflow  rates.
• Meet  minimum R-values in accordance with the
  2012 International  Energy Code.
• Manage the flow of  heat and water vapor through
  all enclosure  assemblies to avoid condensation on
  materials inboard of the drainage plane.

Insulating materials must  be  used  to manage heat
flow in order to  keep the surface temperature of low-
permeability materials inside the enclosure above the
expected dew point. A continuous  thermal barrier is
also necessary to prevent condensation on the interior
surfaces of exterior walls and ceilings during heating
conditions. The insulation layer must  be continuous
to prevent condensation in low R-value components
of the enclosure (e.g.,  metal framing,  concrete slab
edges and angle iron ledgers). The pen test can be
conducted to trace the thermal  barrier's continuity.

To manage water vapor migration by diffusion, select
materials with appropriate water vapor permeability.
The materials in the wall or roof assembly must
be layered to keep low-perm materials above the
dew point during the heating and cooling seasons
and to allow the assembly to dry out if it  gets wet.
This protection  must be provided in all above- and
below-grade walls, floors, ceilings,  plaza and roof
assemblies, including opaque walls and roofs,  glazed
fenestration and skylights, curtain  wall systems and
exterior doors.

Condensation control  must be provided for typical
sections and at thermal bridges. Many standard
designs in published work detail assemblies that
provide  condensation  control  for various assemblies
in many climates. For example, the International
Building Code covers condensation control for a
variety of wall types and all North American climates.
Straube (2011) includes systematic guidance  for four
fundamental wall and roof assemblies in  all North
American climates, plus a discussion  of underlying
moisture dynamics. (See references below and in
Chapter 2.  For designs and climates not covered
in published guidance, and for buildings with  high
humidity levels indoors [e.g., swimming pools,
                             www.epa.gov/iaq/moisture
hospitals, knitting mills and museums], analyses
should be performed by a knowledgeable person
using one of several computer simulations such as
WUFI or hyglRC.  For more information on managing
condensation in the enclosure and hygrothermal
modeling, see references in Chapter 2).

It is important to  note that a layer of porous material
which can safely store moisture may be used as a
buffer to improve the condensation  resistance of
an assembly. For example, a fibrous cover board
beneath a fully adhered low-slope roofing membrane
reduces the risk of condensation that can damage
the adhesive layer. A concrete masonry backup wall
behind a fluid-applied drainage plane can safely store
moisture in the event of minor seepage.

Design HVAC systems to manage  air flow and control
condensation. HVAC system pressurization may be
used to manage the direction in which air flows
through an enclosure. Controlling pressure in air-
conditioned buildings in hot, humid climates is
crucial to controlling condensation in the enclosure.
Buildings in those climates must  be positively
pressurized to prevent warm, humid outdoor air from
entering building cavities and the building itself.

In climates with a significant cold season, humidified
buildings—such as swimming pools, hospitals and
museums—must  not be positively pressurized,
otherwise humid air will be forced into cold building
cavities.  In cold climates, slight depressurization is a
better strategy for humidified buildings.


 Moisture Control Principle #3: Use Moisture-
 Tolerent Materials

The final moisture control principle  is to use building
materials that can withstand repeated wetting in areas
that are expected to get wet. Adequate control can
be achieved by using moisture-tolerant materials and
by designing assemblies that dry quickly. Moisture-
tolerant materials should be used in areas that:
      get wet by design.
• Are likely to get wet by accident.

Areas that Get Wet by Design
Some locations and materials in buildings are
designed specifically to  be wet from time to time.
12The U.S. Army Corps of Engineers (USAGE), for example, has chosen a maximum allowable air leakage rate of 0.25 cubic feet per minute per square foot of total enclosure
area at a pressure difference of 75 Pascals when tested in accordance with the USAGE test protocol. U.S. Army Corps of Engineers Air Leakage Test Protocol for Building
Envelopes Version 3 May 11, 2012.
                                                    19

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www.epa.gov/iaq/moisture
They include custodial closets, laundry rooms,
kitchens, baths,  indoor pools, spas,  locker rooms,
entryway floors and floors that are regularly mopped or
hosed down.

Areas Likely to Get Wet  by Accident
Some areas are likely to experience water leaks over
the course of time. For example,  spaces that contain
plumbing equipment, such as laundry,  lavatory, bath
and  utility rooms, are prone to water leaks and spills.
Below-grade wall and floor assemblies are at the
bottom  of the building. Water from leaks below grade,
on the surface, or above  grade is likely  to end up on
the lowest floor.  In these areas, use moisture tolerant
materials and assemblies that dry quickly.

Many materials can safely get wet as long as they dry
quickly enough.  Stainless steel, copper, some stones,
china and  porcelain tile contain no nutrients to
support the growth of molds or bacteria, do not absorb
water and are stable  when wet. These characteristics
are why these materials have long been  used in
bathrooms, kitchens  and entryways.

In areas that may get wet from time to time, it is
best to avoid building materials that have proven
to be vulnerable to moisture damage. Among these
moisture-sensitive materials are untreated paper-faced
gypsum board, medium density fiberboard (MDF)
and oriented strand board (OSB). Moisture-sensitive
materials are vulnerable because they may:
• Contain nutrients that are digestible by molds,
  bacteria or wood-decaying molds.
• Quickly and easily absorb liquid water and, once
  wet, take longer to dry than materials that are
  impermeable to liquid water.
• Have no anti-microbial characteristics.
• Delaminate,  crumble, dissolve or deform when wet
  or while drying.

Substitutes for vulnerable materials are now
commonly available at only a modest increase in cost.
For example, mold- and moisture-resistant gypsum
board, fiber cement board tile backers and sub-floors
are available in home improvement stores  in addition
to builders' supply yards.

If in doubt, the moisture-resistant properties of
a building material can be determined by testing
according to ASTM  D3273-00 (2005) Standard
Test Method for Resistance to Growth of Mold on
the Surface of Interior Coatings in an Environmental
Chamber. Designers can ask the manufacturer for  the
results of these tests.
REFERENCES
The following references are included for further
reading and guidance.

Advanced Energy. Crawl Spaces. Advanced Energy. http://www.
   crawlspaces.org/. Accessed Novembers, 2013.
   (This condensed document provides details and  technical
   information for designing and constructing closed, insulated
   residential crawl spaces. The full research reports underlying
   the crawl space recommendations can also be downloaded
   from the site www.crawlspaces.org. Although the research
   was conducted in North Carolina, many of the results can be
   applied to other climates.)

Air Conditioning Contractors of America. Manual D, Residential
   duct systems. Arlington, VA:. (This guidance for duct design
   and installation is the basis for building codes in several
   states and  is an ANSI-approved national standard.)

Air Tightness Testing and Measurement Association.
   2006. Technical standard 1 measuring air permeability of
   building envelopes. Air Tightness Testing and  Measurement
   Association
American Society for Testing and Materials. E06.41. ASTM
    El 554-03 standard test methods for determining external air
    leakage of air distribution systems by fan pressurization.

American Society for Testing and Materials. ASTM D 3273
    standard test method for resistance to growth of mold on the
    surface of interior coatings in an environmental chamber.

American Society for Testing and Materials. E06.41. ASTM £779-
    03 standard test method for determining air leakage rate by
    fan pressurization.

American Society for Testing and Materials. E06.41. ASTM
    El 554-03 standard test methods for determining external air
    leakage of air distribution systems by fan pressurization.

American Society for Testing and Materials. ASTM WK8681 new
    standard test method for resistance to mold growth on interior
    coated building products in an environmental chamber.

American Society of Heating, Refrigerating And Air-Conditioning
    Engineers (ASHRAE). 2004. Position Document on Limiting
    Indoor Mold and Dampness in Buildings, http://tinyurl.com/
    ASHRAE-Mold-PD
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American Society of Heating, Refrigerating And Air-Conditioning
    Engineers (ASHRAE). 2004.  Ventilation for acceptable indoor
    air quality, standard 62.1-2004. Atlanta, GA: ANSI/ASHRAE.
    (The ASHRAE ventilation standard provides information
    needed to determine ventilation rates for differing
    occupancies plus a number of design operating and
    maintenance requirements to ensure proper performance
    of ventilation equipment. Section 6.2.8 specifically deals
    with exhaust ventilation. Standard 62.1 applies to many
    situations.)

American Society of Heating, Refrigerating And Air-Conditioning
    Engineers (ASHRAE). 2004. Ventilation and acceptable indoor
    air quality in low rise residential buildings, standard 62.2-
    2004. Atlanta, GA:  ANSI/ASHRAE.
    (This standard applies to low-rise residential buildings. Exhaust
    systems are covered in portions of sections 5, 6 and 7.)

American Society of Heating, Refrigerating and Air-Conditioning
    Engineers (ASHRAE). 2004.  Energy standard for buildings
    except low-rise residential buildings standard 90.1-2004.
    Atlanta, GA: ANSI/ASHRAE.
    (This standard provides minimum requirements for the
    energy-efficient design of all buildings, with the exception of
    low-rise residential  buildings.)

American Society of Heating, Refrigerating and Air Conditioning
    Engineers (ASHRAE). 2008.  Design criteria for moisture
    control in buildings, standard  160 P. Atlanta, GA: ANSI/
    ASHRAE.

ANSI/AMCA. 2007. AMCA standard 500-L-07 Laboratory
    methods of testing louvers  for rating. AMCA.

Atlanta Regional Commission. 2001. Georgia Stormwater
    Management Manual, Volume 2: Technical Handbook.
    (Volume 2 of the Technical Handbook provides guidance on
    the techniques and measures that can be implemented to
    meet a set of storm water management minimum standards
    for new development and redevelopment. Volume 2 is
    designed to provide the site designer or engineer with
    information required to effectively address and control both
    water quality and quantity on a development site. This
    includes guidance on better site design practices, criteria
    for selection and design of  structural storm water controls,
    drainage system design  and construction and maintenance
    information.)

Baker, M.C. 1972. Drainage From Roofs. Canadian Builders
    Digest. 151. Ottawa.
    (This digest is a general discussion of  roofs and roof  drainage
    and highlights many roof drainage design considerations.)

Brennan, T., J.B. Cummings, and J. Lstiburek. 2002. Unplanned
    Airflows and Moisture Problems. ASHRAE Journal. Nov.
    2002: 44-49.
    (This article reviews the moisture dynamics caused by
    unplanned airflows during heating and cooling modes, and
    discusses interventions that can be made to prevent  or solve
    the problems.)

Building Sciences Corporation. 2005.  Read This Before You
    Design,  Build or Renovate.
    Revised May 2005.  http://www.buildingscience.com/
    documents/guides-and-manuals/gm-read-this-before-vou-
    design-buiId-renovate. Accessed November 6, 2013.
    (This pamphlet offers guidance about  remodeling practices
    that foster healthy homes by reducing  occupants' risk of
                                  www.epa.gov/iaq/moisture

    exposure to known hazards. These practices also frequently
    yield other benefits such as improved durability and reduced
    operating costs.)

Canada Mortgage and Housing Corporation (CMHC). 2004. Best
    Practice Guide Building Technology: Glass and Metal Curtain
    Walls. C.M.H.C.

Canada Mortgage and Housing Corporation (CMHC). 2003. Best
    Practice Guide Building Technology: Fire and Sound Control
    in Wood-Frame Multi-Family Buildings. C.M.H.C.

Canada Mortgage and Housing Corporation (CMHC). 2002. Best
    Practice Guide Building Technology: Architectural Precast
    Concrete: Walls and Structure. C.M.H.C.

Canada Mortgage and Housing Corporation (CMHC). 2006. Best
    Practice Guide Building Technology: Brick Veneer Steel Stud.
    C.M.H.C.

Canada Mortgage and Housing Corporation (CMHC). 1997. Best
    Practice Guide Building Technology: Brick Veneer Concrete
    Masonry Unit Backing. C.M.H.C.

Canada Mortgage and Housing Corporation (CMHC). 2006. Best
    Practice Guide Building Technology: Flashings. C.M.H.C.

Canada Mortgage and Housing Corporation (CMHC). 2006. Best
    Practice Guide Building Technology: Wood Frame Envelopes.
    C.M.H.C.

Canada Mortgage and Housing Corporation (CMHC). 2006. Best
    Practice Guide Building Technology: Wood-Frame Envelopes
    in the Coastal Climate of British Columbia. C.M.H.C.

Connecticut Department of Environmental Protection. 2004
    Connecticut Stormwater Quality Manual, ed. Jane
    A. Rothchild.  Hartford: Connecticut Department of
    Environmental Protection.
    (This manual  provides guidance on the measures necessary to
    protect waters from the adverse impacts of post-construction
    storm water. The guidance is applicable to new development,
    redevelopment,  and upgrades to existing development.
    The manual focuses on site planning, source control, and
    pollution prevention, and storm water treatment practices.)

Department of the Army. 1994. Site Planning and Design, TM
    5-803-6.
    http://www.wbdg.org/ccb/ARMYCOE/COETM/ARCHIVES/
    tm 5  803  14.pdf. Accessed November 6, 2013.
    (This technical manual describes the site planning and
    design process used to develop a project to fulfill facility
    requirements  and create the optimal relationship with the
    natural site. The manual focuses on the site planning and
    design process as it leads from program and site analysis to
    the preparation of a concept site plan.)

Ferguson, B.K. 2005. Porous Pavements.  Boca Raton: CRC Press
    (This book provides comprehensive guidance and case
    histories for design, construction and maintenance, based on
    25 years of practical experience with  porous pavements, their
    hydrology and their relationship to storm water drainage and
    surface water management for buildings, roads, parking lots
    and landscape vegetation.)

Gatley, D.P. 2000. Dehumidification Enhancements for
    100-Percent-Outside-Air AHU's: Simplifying the decision-
    making process, Part  1. HPAC Heating/Piping/AirConditioning
    Engineering Sept.: 27-32.
                                                             21

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www.epa.gov/iaq/moisture

    (This three-part series of articles describes the underlying
    psychrometrics in ventilating buildings and  provides
    design guidance for several methods of enhancing the
    dehumidification performance of air conditioning and
    ventilation systems.)

Gatley, D.P. 2000.  Dehumidification Enhancements for
    100-Percent-Outside-Air AHU's: Recuperative heat exchange
    is an energy-efficient way to accomplish reheat while also
    reducing cooling capacity, Part 2. HPAC Heating/Piping/
    AirConditioning Engineering Oct.: 51-59.
    (This three-part series of articles describes the underlying
    psychrometrics in ventilating buildings and  provides
    design guidance for several methods of enhancing the
    dehumidification performance of air conditioning and
    ventilation systems.)

Gatley, D.P. 2000.  Dehumidification Enhancements for
    100-Percent-Outside-Air AHU's: Enthalpy heat exchange,
    the use of desiccants, and vapor compression dehumidifiers
    are cost effective ways to maintain healthy and comfortable
    buildings,  Part 2.  HPAC Heating/Piping/AirConditioning
    Engineering N ov.:  51-59.
    (This three-part series of articles describes the underlying
    psychrometrics in ventilating buildings and  provides
    design guidance for several methods of enhancing the
    dehumidification performance of air conditioning and
    ventilation systems.)

Harriman,  L, Brundrett, G. and Kittler, R.  2001. Humidity
    Control Design Guide for Commercial and Institutional
    Buildings. Atlanta, GA: ASHRAE. (This manual by ASHRAE
    is an effort to expand the design of cooling equipment to
    include dehumidification performance. Design  analysis
    includes peak outdoor air dew point performance as well as
    peak outdoor temperature analysis.)

Henderson, H.I., D.B. Shirey, and R.A. Raustad. 2003.
    Understanding the Dehumidification Performance of
    Air Conditioning Equipment at Part-Load Conditions.
    Presentation, ClBSE/ASHRAE Conference, Edinburgh,
    Scotland. September 24-26, 2003.
    (This technical paper presents analysis and  data on
    the degradation of dehumidification performance of air
    conditioning equipment during part-load conditions. Controls
    and systems that contribute to this problem are discussed.)

HyglRC (A hygrothermal modeler from the  Institute for Research
    in Construction in Canada http://archive.nrc-cnrc.gc.ca/
    eng/projects/irc/hygirc.html. Accessed November 6, 2013.
    HyglRC is a sophisticated modeler that is actively supported
    by the IRC. Workshops are available. Like WUFI and MOIST,
    HyglRC assumes no airflow through the assembly.)

International Code Council (ICC).  2012.  International Building
    Code 2012. ICC.
    (Chapter 18 provides code requirements for soils and
    foundations including requirements for excavation, grading
    and fill around foundations.  Section 1203.3.1  contains
    requirements for ventilated crawl  spaces.)

International Code Council (ICC).  2012.  International Plumbing
    Code 2012. ICC.
    (Chapter 11 provides code requirements for storm drainage,
    including roof drainage  requirements.  Section 312.2 to
    Section 312.5 specify a gravity test of the drain and vent
    side of plumbing systems.)
International Code Council (ICC). 2012. 2012 International
    Energy Conservation Code. ICC.
    (The IECC addresses energy efficiency in homes and
    buildings. IECC is the successor to the council for American
    Building Code Officials [CABO] Model Energy Code [MEC].
    The IECC is revised on a 3-year cycle with a supplement
    issued half-way through the cycle.  Revisions to the code
    occur through an open,  public hearing process, and each
    code or supplement is denoted with the year it was adopted
    [e.g., 2006 IECC].)

Kanare,  H. 2005. Concrete Floors and Moisture. Skokie, Illinois:
    Portland Cement Association.

Lstiburek, Joseph 2006. Understanding Attic Ventilation.
    ASHRAE Journal 48:  36.

Lstiburek, Joseph 2006. Understanding Basements. ASHRAE
    Journal 48: 24

Lstiburek, Joseph 2006. Understanding Drain planes. ASHRAE
    Journal 48: 30
     (This ASHRAE Journal article covers the  underlying
    principles of rainwater control  in buildings, focusing on
    the  use of weather-resistant materials that provide shingled
    drainage beneath siding  materials.)

Lstiburek, Joseph 2004. Understanding Vapor Barriers. ASHRAE
    Journal 46: 40
     (This ASHRAE article describes water vapor dynamics in
    wall sections and provides a flow-chart method of selecting
    materials for the inside and outside of cavity walls that have
    appropriate water vapor permeability for specific climates.
    Assemblies can be designed without resorting to computer
    simulation.)

National Asphalt Pavement Association. Online.  Internet.
    Available at http://www.asphaltpavement.org/.
    (The National Asphalt Pavement Association is a trade
    association that provides technical, educational, and
    marketing materials and  information to its members, and
    supplies technical information concerning paving materials.)

National Council of Architectural Registration  Boards (NCARB).
    Odom, J.D. and DuBose, G.H.  2005. Mold and Moisture
    Prevention.Washington, D.C. (This  manual is the 17th
    monograph in NCARB's Professional Development Program. It
    describes moisture and  mold problems in buildings, specific
    design and construction considerations for enclosures, and
    HVAC systems as they relate to moisture and mold problems.)

National Institute of Building Sciences  (NIBS). Building Envelope
    Design Guide, http://www.wbdg.org/design/envelope.php.
    Accessed November 6, 2013.
    (The NIBS, under guidance from the Federal Envelope
    Advisory Committee, has developed this comprehensive guide
    for exterior envelope design and construction for institutional
    and office buildings. Sample specifications and sections are
    included.)

Rose, W. B. 2005. Water in Buildings: An Architect's Guide to
    Moisture and Mold. New York:  John Wiley & Sons.
    (This is not a design guide, but rather a deeper look at water
    and its peculiar behavior in regard  to building materials,
    assemblies, and whole buildings. Illustrated with specific
    examples, it explains the how and why of  moisture control.)

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Sheet Metal and Air Conditioning Contractors' National
    Association. 1985. SMACNA Air Duct Leakage Test Manual.
    Virginia. Sheet Metal and Air Conditioning Contractors'
    National Association.
    (A companion to HVAC Duct Construction Standards - Metal
    and Flexible, this manual contains duct construction leakage
    classification, expected leakage rates for sealed and unsealed
    ductwork,  duct leakage test procedures, recommendations on
    use of  leakage testing, types of test apparatus and test set-up
    and sample leakage analysis.)

Sheet Metal and Air Conditioning Contractors' National
    Association. 1993. Architectural Sheet Metal Manual -
    Fifth Edition. Virginia. Sheet Metal and Air Conditioning
    Contractors' National Association.
    (The SMACNA Architectural Sheet Metal Manual provides
    design  criteria and  details for roof drainage systems, gravel-
    stop fascia, copings, flashing, building expansion, metal
    roof and wall systems, louvers and  screens and other metal
    structures. Chapter 1 contains data, calculations, and charts
    for designing roof drainage systems.)

Spray Polyurethane Foam Alliance. 2003. Spray Polyurethane
    Foam for Exterior Subgrade Thermal and Moisture Protection.
    Virginia: Spray Polyurethane Foam  Alliance.
    (A technical guide to specifying closed-cell spray foam
    polyurethane on the outside of basement walls as thermal
    insulation and moisture protection.)

Straube, John. 2011. High Performance Building Enclosures.
    Somerville, MA:  Building Science  Press (This book includes
    the fundamentals underpinning the physics of heat, air and
    moisture control in high-performance building enclosures and
    practical design guidance to achieve them for a wide array of
    enclosure  assemblies in all North American climate zones.)

Texas Water Development Board. 2005. The Texas Manual on
    Rainwater Harvesting. Texas: Texas Water Development
    Board,  http://www.twdb.state.tx.us/innovativewater/rainwater/
    docs.asp. Accessed Novembers, 2013.
    (This manual  presents a discussion on the history of rainwater
    collection, harvesting system components, water quality and
    treatment, system sizing and best management practices.)

United States Environmental  Protection Agency. 2006. Alternative
    Pavers (Post-Construction Storm Water Management in New
    Development and Redevelopment). Washington, D.C.: United
    States  Environmental Protection Agency, http://cfpubl.epa.
    gov/npdes/stormwater/menuofbmps/index.cfm?action=min
    measure&min measure id=5. Accessed November 6, 2013.
    (This resource is intended to provide guidance on the types of
    practices that could be used to develop and implement storm
    water management programs.)
                                  www.epa.gov/iaq/moisture

United States Environmental Protection Agency. 2006
    Construction Site Storm Water Runoff Control. Washington,
    D.C.: United States Environmental Protection Agency.
    (This resource provides detailed information on construction-
    phase storm water management, including best management
    practices.)

United States Environmental Protection Agency. 2006. National
    Menu of Storm Water Best Management Practices.
    Washington, D.C.: United States Environmental Protection
    Agency. (This resource provides detailed information
    including applicability, design criteria, limitations and
    maintenance requirements on these and many other site
    drainage methods.)

United States Environmental Protection Agency. 2006.Porous
    Pavement. Post-Construction Storm Water Management in
    New Development and Redevelopment.
    http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.
    cfm?action=min  measure&min  measure id=5. Accessed
    November 6, 2013.

United States Environmental Protection Agency. 2001. Managing
    Storm  Water to Prevent Contamination of Drinking Water.
    Source Water Practices Bulletin. EPA 816-F-01-020.
    Environmental Protection Agency.
    http://www.epa.gov/safewater/sourcewater/pubs/fs swpp
    stormwater.pdf. Accessed November 6, 2013.
Water Management Committee of the Irrigation Association. 2010
    Turf and Landscape Irrigation: Best Management Practices.
    Irrigation Association.

WUFI: Hygrothermal modeling software to assess the water vapor
    dynamics of wall and roof systems in numerous climates.
    WUFI is available from the Fraunhofer Institute of Building
    Physics http://www.hoki.ibp.fraunhofer.de/ in Germany and
    Oak Ridge National Laboratory http://www.ornl.gov/sci/
    btc/apps/moisture/. Accessed November 6, 2013. ORNL
    conducts training for using WUFI.

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www.epa.gov/iaq/moisture
 The Basics  of  Water Behavior
Water occurs at temperatures often found in buildings
as a liquid, a gas (water vapor) and in an in-between
state (adsorbed on solid surfaces).

Liquid water moves from one place to another in
several ways:
• Water runs through pipes and vessels. Water moves
  from higher pressure to lower pressure in pipes and
  fixtures. A leak in  a  pressurized pipe or tank can
  release much more water than a similar leak on the
  drain side of the plumbing system.
• Water runs downhill. Rainwater, surface water,
  spilled water, water  on the drain side of plumbing
  fixtures and water in condensate  pans are all
  affected by gravity.
• Water wicks upwards. Water wicks up through tiny
  cracks and holes.  To see wicking  in action, stand
  two plates of glass on edge in 1A  inch of water.
  Push them together and as they get closer the
  water wicks up between them. The closer together
  the plates, the higher water wicks. This happens
  because water molecules are attracted to the glass
  and to other water molecules. What works for
  cracks works for pores in  materials. Stand a porous
  material like paper,  wood, concrete, a sponge or
  gypsum board on edge  in 1A inch of water and the
  water wicks up into  the material.  How high it goes
  depends on pore size and how quickly the water
  can dry out the sides to the air. Water wicks through
  materials in a process called "capillary action."
  When water is in tiny pores, gravity is not the most
  important force acting on it.
• Water runs along the bottom or sides of materials.
  For the same reasons that water wicks up through
  porous materials, water can cling to the sides
  and bottoms of materials. Water is attracted to
  many materials and to itself. Water from rain or
  a plumbing leak may travel many feet along the
  bottom of a floor joist or roof truss before collecting
  in a drop big enough to fall. When water first
  condenses on a mirror or  a cooling coil, it clings to
  the vertical surfaces. Water does  not run down until
  the droplets become large enough for gravity to
  overcome the intermolecular forces.
Water vapor migrates from one place to another in
several ways:
• Water vapor in the air goes where the air goes.
  This is, by far, the fastest and largest mechanism
  of water vapor transport. All air, whether inside or
  outside of buildings,  is constantly moving from
  areas of higher pressure to areas of lower pressure.
  If dry air is pulled into the building from outdoors,
  it will dehumidify the indoor air. If humid  air is
  pulled in, it will add to the humidity load that must
  be removed by the mechanical system.
• Water vapor migrates through materials by
  diffusion. Liquid water may not be present and
  nothing may appear to be wet, but water vapor can
  still slowly  migrate through what appears to be solid
  materials. Vapor molecules will slowly bump their
  way through the spaces between molecules of the
  material. The molecules are moving from an area
  of higher water vapor concentration to lower water
  vapor concentration.  The more porous a material is,
  the easier it is for water vapor to diffuse through it.
  The rate water vapor  diffuses through a material  is
  measured in "perms." Higher perms mean higher
  water vapor flow rates.

Water changes from liquid to gas (evaporation) and
from gas to liquid (condensation).
• Water evaporates from liquid water on surfaces,
  becoming water vapor. Most of the water vapor
  that originates inside buildings is the result of
  evaporation from open containers, sprays or damp
  porous materials. Showers, fountains, pools, sinks,
  pots on stoves, dishwashers and wash water on
  floors are all sources  of indoor humidity, as are
  the building occupants themselves. People, plants
  and animals release water vapor.  In typical office
  spaces, the occupants are probably the main source
  of water vapor. Wet materials such as wet  concrete
  or exposed  earth in crawl spaces or basements are
  also sources of indoor humidity. The evaporation
  rate depends  on  many factors including the
  temperature of the water and the relative humidity
  of the air. The warmer the water, the drier the air
  next to the  wet surface. The faster air blows across
  a wet surface, and the larger the exposed surface
                                                   24

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  area, the greater the evaporation rate. It takes more
  energy to evaporate water from porous materials
  than from impermeable materials because the water
  molecules are more tightly bound by capillary forces
  and it is difficult to blow dry, ventilating air through
  many porous building materials.
• Water vapor condenses on a surface, becoming
  liquid. If surface temperatures are below the  dew
  point of the air next to them, water molecules in the
  surrounding air will condense on the cool surfaces.
  Cold water pipes, air conditioning ducts and cold
  roof decks experience condensation, just like a cold
  drink sweats in the humid summer air.
                           www.epa.gov/iaq/moisture
Water vapor is adsorbed onto surfaces. Water as a
gas moves around very freely. Water adsorbed onto
a solid surface is far less free to move around than
water vapor. In this state, it takes more energy to
break the water free than if it is a liquid or a gas.
Water molecules clinging to a solid surface are less
available for chemical or biological activity than is
liquid water.
                                                    25

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www.epa.gov/iaq/moisture
  Chapter 2: Designing for Moisture Control
 Introduction

The most common participants in the process of
designing a building are architects, engineers,
landscape architects and the clients. The design team
can also include:
• The owner of the building, if the building is being
  designed and built for a specific person or entity.
  The owner can help identify how and by whom the
  building will be used.
• The future occupants of the building,  if they are
  known at the time the building is designed. They
  can help set goals for durability, maintainability and
  moisture protection.
• Building and grounds personnel representing the
  owner, who can provide years of building operation
  and maintenance (O&M) experience.
• The contractor that will construct the building,
  if the contractor has  been selected when the
  design work begins.13 Experienced contractors and
  subcontractors can bring the realities of managing
  moisture during  construction to the design of the
  building.

Where there is a shortage of real estate for sale
or rent, buildings are often designed and built
on speculation. In  such cases, the occupants,
programs and processes that eventually will reside
in the building are known only in general terms. For
example, when  planning an office building, the design
team can assume the occupants will be ordinary office
workers and the building  will have no special sources
of liquid water or humidity. However,  the resulting
design  will not have the benefit of input from the
owner,  the actual occupants or the building and
grounds staff that will have to make the building work
over the years.
 Designing Effective Moisture Controls

Providing good moisture control in the design of a
building is  largely the responsibility of the design
team. Third parties that provide construction
management or commissioning services may play
critical roles in the design and implementation of
moisture controls. A construction management service
may participate in the management of the project at
varying levels from inception, design and construction
to turnover and occupancy. The goal of construction
management ordinarily is to manage the schedule,
cost and quality to the owner's satisfaction, but if a
construction manager is part of the design team, it
is crucial that the manager take on responsibility for
implementing the team's moisture control objectives.
 Building Commissioning

HVAC systems have been commissioned for many
years by testing, adjusting and balancing (TAB).
However, commissioning entire buildings is a
relatively recent innovation in construction. In
1996, ASHRAE published The HVAC Commissioning
Process Guideline 1-1996, which extended the
scope of traditional TAB to include point-to-point
testing of digital controls and functional performance
testing to assess the performance of electrical and
mechanical systems that work together. Since then
this process has been extended to the electrical
systems; potable, sanitary, drainage and irrigation
systems; power production and cogeneration systems;
the building enclosure; sustainable aspects of the
project; and the entire building design process itself.
In 2005, the U.S. General Services Administration
(GSA) published The Building Commissioning Guide.
The guide provides a process for  including building
commissioning in the planning, design, construction
and post-construction phases of a project. A table
in the guide summarizes commissioning activities
and recommends the commissioning agent review
the design for, among other things, the enclosure's
thermal and moisture integrity and its moisture vapor
13 Whether or not the contractor is on board during the design process, the contractor will have the important role of clarifying the design team's intentions regarding moisture
control, planning measures to control water during construction, and preparing response plans for accidental water events that occur during construction. This role is explored in
detail in Chapter 3.
                                                   26

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control. If a commissioning agent is involved in the
design and construction of a building,  many of the
quality assurance procedures related to moisture
control and associated measures could easily fall
within the agent's scope. A general process for
building commissioning is presented in ASHRAE
Guideline 0-2005: The Commissioning Process—
the industry-accepted commissioning guideline.
The National  Institute of Building Science (NIBS)
published Guideline 3-2006: Exterior Enclosure
Technical Requirements for the Commissioning
Process, which presents a  process for building
enclosure commissioning and contains many annexes
to illustrate the steps in the process. In 2012,
ASTM published E2813-12 Standard Practice for
Building Enclosure Commissioning. This standard
practice follows Guideline  3 procedures and includes
functional testing required for fundamental and
enhanced enclosure commissioning.


 Who Should Read this Chapter

This chapter is for the design team members who
produce the design, bid and construction documents.
It includes a list  of design elements that will
protect a building from moisture-related problems.
The design team must understand the  problems
that water causes in buildings and the dynamics
of moisture sources, moisture migration and
moisture control. This knowledge must be reflected
in the design  documents, building drawings and
specifications.

Good  design is a prerequisite for a building
that resists moisture problems; however, good
design alone is not enough. The design must be
implemented  correctly during construction and
maintained during the building's operation by the
owner or manager. To that  end, the design team in
                            www.epa.gov/iaq/moisture
cooperation with the owner, contractor and third
parties:
• Documents overall moisture control goals.
• Plans water controls and water event responses to
  be implemented during construction.
• Identifies inspection, testing, commissioning and
  quality-assurance activities to ensure the intended
  moisture-control measures are implemented as
  designed.
• Establishes requirements of and responsibility for
  providing,  reviewing and accepting submittals, shop
  drawings, proposed substitutions and scheduled
  inspections.
• Documents the O&M procedures required to keep
  the intended moisture control measures working
  throughout the building's life.

This chapter has six subsections:
1.  Site Drainage.
2.  Foundations.
3.  Walls.
4.  Roof and Ceiling Assemblies
5.  Plumbing Systems.
6.  HVAC Systems.

Each subsection discusses techniques to provide
protection from moisture problems and specifies:
• The issue that is being addressed.
• The moisture-control goals for the issue.
• Guidance on implementing techniques to achieve
  each moisture-control goal.
• Ways to verify that the moisture-control techniques
  have been included  in the building design and have
  been properly installed or constructed.
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 Site  Drainage
Issue
Water from rain, snowmelt and irrigation systems
can infiltrate a building, damaging the structure and
its contents. Properly designed site drainage avoids
building damage and the need for  potentially costly
remediation.14



Design the site so that water from  rain, snowmelt and
landscape irrigation is  prevented from entering the
building.

Guidance

Guidance 1: The site drainage design creates a
controlled condition to help move water away from the
building. To the extent possible, the design maintains
the rate of water-soil infiltration (i.e., the downward
entry of water into the  surface of the soil) at the site
before the site was disturbed. Runoff (i.e., water that
does not  infiltrate into  the soil) must be managed by
other drainage methods.

Guidance 2: Avoid unnecessary impervious surfaces.
Avoiding  unnecessary or large impermeable surfaces—
or using alternative, relatively permeable paving
materials—will allow more water to infiltrate, thus
reducing the size and cost of systems managing
runoff. Placing facilities on a site changes the site's
drainage  characteristics by increasing the  impervious
area, which, in turn, increases the  volume of runoff
that must be managed. Where large expanses of
impervious surface are unavoidable, such as parking
lots, breaking the expanse into smaller areas or  using
alternative permeable pavement techniques  can help
reduce runoff.

Alternative paving materials such as  pervious
pavement, modular porous paver systems or  other
surfaces can be used to reduce runoff.
• Porous pavement is a permeable surface often built
  with an underlying stone reservoir that temporarily
  stores surface runoff before it infiltrates into the
  subsoil. Porous pavements may be made using
  asphalt or concrete. Medium-traffic areas are the
  ideal application for porous pavement. Porous
  pavement may be inappropriate in  areas such as
  truck loading docks and areas where there is a great
  deal of commercial  traffic.
• Modular porous pavers are permeable surfaces
  that can replace asphalt and concrete; they can
  be used for driveways, parking lots and walkways.
  Alternative pavers can replace  impervious surfaces,
  resulting in less storm water runoff.
• The two broad categories of alternative pavers are
  paving blocks and other surfaces, including gravel,
  cobbles, wood, mulch, brick and natural stone.

Guidance 3: Use grading to slow down runoff and
achieve a more balanced infiltration rate. Topography
helps determine the amount, direction and rate
of runoff. To the extent possible,  retain existing
contours  so that the existing drainage patterns can
be maintained. Grading also can  be used to correct
drainage  problems. Where steep slopes contribute to
rapid runoff, re-grading  to more moderate slopes can
reduce runoff velocity.

Guidance 4: Ensure positive site drainage principles
are  met,  including:
• Making certain water  is moved away from the
  building.
• Ensuring water is not  allowed to accidentally  pond
  in low areas.
• Making sure the finished floor is elevated enough  so
  that water will not back up into the building if the
  drainage systems are  blocked.

Figure 2-1 illustrates positive drainage principles.
14 This document does not address flood waters from rivers or lakes, the sea or from other extreme weather events.

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Figure 2-1 Positive Drainage Principles
                                                                                    www.epa.gov/iaq/moisture
                                                                                5% minimum grade
                                                                                for first 101

                                                                                2% minimum grade on
                                                                                lawn areas
                                                                                0.5% minimum grade on
                                                                                pavement
    Typical 8" drop at
    foundation

               Ensure positive drainage by
               maintaining height of berms or
               obstructions below floor elevations
Guidance 5: When runoff must be controlled and
redirected away from the building, identify and design
water runoff management approaches appropriate for
the site's characteristics. Potential approaches to use
include:
• Infiltration control methods such as swales or
  infiltration trenches.
  • A swale (i.e., a grassed channel, dry swale,
    wet swale, biofilter or bioswale) is a vegetated,
    open-channel management practice designed
    specifically to treat and attenuate runoff for
    specified water quality and volume. As water
    flows along these channels, vegetation slows it to
    allow sedimentation; the water filters through  a
    subsoil matrix or infiltrates the underlying soils or
    both.
  • An infiltration trench (i.e., infiltration galley)
    is a rock-filled trench with no outlet that
    receives runoff. The runoff passes through some
    combination of pretreatment measures, such as
    a swale and detention  basin, and into the trench.
    Runoff is stored in the spaces between the stones
    in the trench and from there infiltrates through
    the trench bottom and into the soil. The primary
    pollutant removal  mechanism of this practice is
    filtering through the soil.
• Retention or detention control methods such as wet
  or dry ponds.
  •  Wet ponds—storm water ponds, wet retention
     ponds and wet extended-detention ponds—are
     constructed basins that contain a permanent
     pool of water throughout the year or  at least
     throughout the wet season.  Ponds treat incoming
     runoff by allowing particles  to settle and algae
     to take up  nutrients. The primary removal
     mechanism is settling, which occurs as runoff
     resides in the pond. Pollutant uptake, particularly
     of nutrients, occurs through biological activity.
     Wet ponds traditionally have been widely used as
     a storm water best  management practice.
  •  Dry detention ponds—dry ponds, extended
     detention basins, detention  ponds and extended
     detention ponds—hold runoff  for some minimum
     time to allow particles and associated pollutants
     to settle. Unlike wet ponds,  these facilities do not
     have a large permanent pool of water; however,
     they are often designed with small pools at the
     basin's inlet and outlet. Dry detention ponds
     also can contribute to flood  control  by providing
     additional flood water storage.
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For detailed information including applicability,
design criteria, limitations and maintenance
requirements on these and many other site drainage
methods, visit EPA's storm water management
website.15

Guidance 6: Landscape irrigation systems must be
designed so that they do not spray the building or
soak the soil next to the foundation. Consider hiring
a qualified  irrigation designer or irrigation consultant
to design the system, keeping in mind these
considerations:

• Spray heads and rotor heads spray water into the
  air. When designing spray systems consider wind
  conditions. Wind can carry airborne water beyond
  the area  intended to be covered,  and the sprinklers
  may spray the building or the soil around the
  foundation.
• Drip irrigation is a slow, even application of water
  through plastic tubing that delivers water directly
  to plants. Drip irrigation systems use less water
  than spray systems; however, they still can soak the
  ground around the foundation and cause moisture
  problems in a building.
• All  irrigation systems, regardless  of type, should be
  properly controlled and monitored. Timers should be
  installed to  ensure the system shuts off. Water flow
  meters should be  installed to measure the volume
  of water moving through the system. Regularly
  monitored meters can be a source of information
  about excessive water use  due to timer problems
  or system leaks. Consider installing devices such
  as tensiometers or soil blocks to measure soil
  moisture.

Guidance 7: Ensure water draining from one building
or site does not violate the good drainage of an
adjacent building or site. This can happen when a
building is  constructed  close to an existing building
and dumps drainage water (e.g., roof, surface, etc.)
onto or at the  existing building,  overwhelming its
drainage features.

Guidance 8: Consider green building practices that
minimize the need for irrigation or that capture
rainwater for use in  irrigation.
• Select trees, shrubs, ground cover and other
  landscaping elements based on their ability to grow
  well with little or no additional water. Such plants
  will minimize the use of water for irrigation.
• Explore the potential for capturing, diverting and
  storing rainwater for landscape irrigation, drinking
  and other uses. This approach can be used in all
  climates. For more information, see the Texas Water
  Development Board reference The Texas Manual on
  Rainwater  Harvesting.

Guidance 9:  Develop a construction-phase storm-
water-management plan. The  plan should address at  a
minimum:
• Methods for minimizing the potential for storm
  water runoff during construction.
• Methods to drain storm water from the site and
  away from  the structure during construction.
• Methods for preventing building materials from
  getting wet.
• Methods for keeping the building or portions of the
  building dry during construction.16
• Policies and methods for drying materials and the
  building if  they become wet.
• Construction-phase storm water management
  supervisory roles and responsibilities.

For detailed information on construction-phase storm
water management, visit EPA's storm water best
management practices website.17

Guidance 10: Develop guides covering the O&M of
the storm water management  system. The guides
should include:
• The theory of operation of storm-water-management
  systems.
• Inspection  procedures.
• Maintenance procedures and requirements.

For detailed information on post-construction storm
water management, visit EPA's storm water best
management practices website.18
15 http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm. Accessed Novembers, 2013.

16 For some large projects, interior work may begin before the upper floors have been completed. Special rainwater-control measures are needed to protect the lower floors. See
Chapter 3 on the construction phase for more details.

17 http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm. Accessed Novembers, 2013.

18http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm. Accessed Novembers, 2013.
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                                                                                   www.epa.gov/iaq/moisture
Verification of Site Drainage                           • Provide the construction manager and the building
                                                        owner with a list of post-construction inspection
• If storm water from the site is to be conveyed to          and maintenance requirements for the site drainage
  a municipal separate storm sewer system (MS4),         systems.
  get a list of MS4 operator's requirements for the
  municipality. Give the list to the construction
  manager before construction  begins.
• Provide the construction  manager with a list
  of construction-phase critical details and an
  inspection schedule of the site drainage system,
  identifying the sequence of inspections, parties
  responsible for the inspections, and required
  documentation of the inspection results.
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www.epa.gov/iaq/moisture
  Foundations
Issue
Building foundations are vulnerable to moisture
problems for a number of reasons, including:

• Water from rain and from plumbing leaks is drawn
  by gravity to foundations, which are exposed to
  surface water, rain-soaked soil and, possibly, high
  water tables.
• Water may condense on foundation materials during
  warm weather because the materials are cooler than
  the outdoor air.
• Crawl spaces and basements are holes in the
  ground and have more extensive contact with soil
  than slab-on-grade foundations.
• Many moisture problems can be avoided by properly
  designing the foundation. Moisture problems
  associated with improperly designed foundations
  can be difficult and expensive to identify and
  fix, can create the potential for health problems
  resulting from mold growth, and can be a liability
  for building owners.




Foundation Design Goal 1: Design the foundation to
prevent rainwater and groundwater incursions.

Foundation Design Goal 2: Avoid condensation on
slab-on-grade foundations, in crawl spaces and in
basement foundations.

Guidance

Foundation Design Goal 1: Design the foundation to
prevent rainwater and groundwater incursions.

Guidance 1: Plan the surrounding slope to divert
water away from the building. This guidance applies
to slab-on-grade foundations, crawl spaces and
basements.
• Specify a 5 percent—6 inches per 10 feet—slope
  to the finish grade away from the foundation to
  control the surface flow of water, or meet a more
  stringent local building code requirement. Applying
  this slope to a distance of 6 to 10 feet from the
  foundation generally is acceptable.
• Reduce water infiltration  into the soil surrounding
  the building using a barrier at or slightly beneath
  the surface (e.g.,  a cap of silty-clay soil or
  subsurface drainage landscape membrane). Care
  must be taken to  prevent the roots of plants in this
  zone from penetrating the barrier.
• Design the foundation and surrounding grade
  so there is a minimum of 8 inches of exposed
  foundation after the final grading.

Guidance 2: Design below-grade drainage systems
to divert water away from the foundation and specify
capillary  breaks to keep water from wicking through
the foundation to moisture-sensitive materials (e.g.,
wooden framing and paper-covered gypsum board).

Slab-On-Grade Liquid Water Control (See Figure 2-2)

Below-grade perimeter drainage is not required
for concrete slab-on-grade foundations when the
surrounding finish grade is sloped as specified in
Guidance 1, the slab is elevated at least 8 inches
above finished grade, and the design includes
appropriate capillary breaks. Incorporate a capillary
break between:
• The foundation and the above-grade wall (e.g., a
  layer of polyethylene foam sill seal, metal  or rubber
  flashing, or a damp-proof masonry course between
  the concrete foundation  and the wood or steel
  framed  walls or the concrete  or masonry walls).
• The earth and the floor slab (e.g.,  a layer of
  coarse  aggregate with  no fines, a plastic or rubber
  membrane, or a layer of  plastic foam insulation
  placed beneath the slab). NOTE: While coarse
  stone will provide a capillary break, a vapor barrier
  directly beneath the slab is required to manage
  water vapor migration.
• The earth and  below-grade portion of the perimeter
  stem wall or thickened edge slab (e.g., damp-proof
  coating or a water-proof membrane placed on the
  thickened edge slab or stem wall).

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                                                                                      www.epa.gov/iaq/moisture
Figure 2-2 Illustration of Ground Water Control for Slab Foundations
                   Down spouts carry rainwater
                   from the roof away from the
                   foundation
                   8" minimum
                    Ground slopes away from
                    the foundation
           Capillary break under plate
           Polyethylene vapor barrier
           in direct contact with
           concrete slab
                                                                     Granular drainage pad
                                                                     (coarse gravel, no fines)
                   Keep rain water away from the foundation perimeter

                   Do not place sand layer over polyethylene vapor barrier under concrete slab

                   Where vinyl flooring Is installed over slabs, a low water-to-cement (w/c) ratio  (= 0.45 or
                   less is recommended] to reduce water content in the concrete; alternatively, the slab
                   should be allowed to dry (less than 0.3 g rams/24 hrs/ff) prior to flooring installation
If there is a joint between the slab's perimeter edge
and a stem wall, a capillary break may be needed
between the edge of the slab and the  perimeter wall
to prevent water wicking from the perimeter wall into
the slab.

If the roof slopes to eaves without gutters, protect the
bottom of the above-grade portion of the wall against
rain splash (e.g., raise the foundation  wall and slab
out of the ground 18 inches or more, or construct the
wall with robust drainage and drain  plane protection).


Crawl Space and Basement Liquid Water Control
(See Figures 2-3 and 2-4)

• Design the basement or crawlspace  so that the
  interior floor grade is above the 100-year flood level
  and the local water table.
• Specify a curtain of free-draining  material (e.g.,
  sand and gravel, coarse aggregate with no fines,  or
  a synthetic drainage mat) around the outside of the
  foundation between the  unexcavated earth and the
  basement wall.
• Specify a drainage collection  and  disposal system
  to be located below the top of the footing or the
  bottom of the slab floor (e.g., perforated exterior
footing drain pipe surrounded by coarse aggregate
with no fines and filter fabric, drained to a preferred
disposal option such as daylight or a sump pump).
Locate the top of the pipe at or below the bottom
of the finished slab regardless of the location of the
pipe with  respect to the footing.
Specify filter fabric to prevent fine soils from
clogging the curtain drain and the footing drain
system.
Incorporate a  capillary break between:
• The top of the foundation wall and the first-floor
  framing system (e.g., a layer of polystyrene sill
  seal,  metal  or rubber flashing,  or a masonry
  damp-proof course between the concrete
  foundation  and  the wood, steel, or concrete floor
  structure).
• The earth and the basement floor slab (e.g., a
  layer of coarse aggregate with no fines, a plastic
  or rubber membrane, or a layer of styrene foam
  insulation placed beneath the slab).
• The free-draining perimeter fill  and the below-
  grade portion  of the basement wall (e.g., a damp-
  proof coating or a water-proof membrane placed
  on the outside of the basement wall).

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    NOTE: A plastic or elastomeric membrane can
    be used in place of a concrete slab to form a
    capillary break and prevent evaporation from
    the soil into the crawl space. A concrete slab
    has the advantages of being more durable and
    of blocking the entry of burrowing rodents.
    Membranes are less expensive and easier to
    install.

• Design a capillary break between the top of the
  footings and foundation walls (e.g., painted-on
  coating).
• Specify a drain in the foundation floor that leads to
  an approved disposal site.
• Include in the plan:
  • Assumptions about maximum rainfall or
    snowmelt.
  • Drainage surface areas including shapes, slopes,
    superstructures or other obstructions.
  • Estimated water flows.
  • The  location and capacities of all sub-grade
    drainage features (e.g., drain  lines, discharge
    locations, man-holes, access pits).

Foundation Design Goal 2: Avoid condensation on
slab-on-grade foundations, in crawl spaces or in
basement foundations.

Slab-on-Grade Condensation

• Insulate slab-on-grade foundations (e.g., install
  extruded styrene foam board beneath the slab) to
  keep the floor from sweating during warm,  humid
  weather.
• Provide perimeter and sub-slab insulation to meet
  the International Energy Conservation Code.
• Provide a vapor retarder sheet directly under the
  concrete floor slab to prevent water vapor from
  infiltrating the floor system. Vapor  retarders should
  meet the requirements of ASTM specification E
  1745 Class A, B or C.

Basement Condensation Control (See  Figure 2-3)

• Specify insulation for the above- and below-grade
  basement walls to meet the ASHRAE Standard
  90.1 requirements. NOTE: Do not insulate
  basement ceilings.
• Provide a vapor retarder sheet directly under the
  concrete floor slab to prevent water vapor infiltration
  through the floor system. Vapor retarders should
  meet requirements of ASTM  specification E 1745
  Class A, B or C.
• Mechanical equipment can be located in basements
  that have insulated walls. Specify air-sealing details
  to provide a continuous air barrier from the above-
  grade wall down the foundation wall and ending in
  the center of the basement floor.  Use the pen test
  (See Appendix A) to trace the continuity of the  air
  barrier. NOTE: The air barrier for  the foundation is a
  part of  the whole building air barrier system.
• Specify a whole building air  leakage rate when
  tested at 75 Pascal  pressure difference in
  accordance with ASTM E779-10 Standard Test
  Method for Determining Air Leakage Rate by
  Fan Pressurization or ASTM  £1827-96(2007)
  Standard Test Methods for Determining Airtightness
  of Buildings Using an Orifice Blower Door. For
  example, the U.S. Army Corps of Engineers  now
  requires a maximum air leakage rate of 0.25 cubic
  feet per minute at 75  Pascal pressure difference.
• When insulating on the outside of foundation walls:
  • Specify insulating materials that can tolerate
    exposure to the earth. Extruded styrene and
    high-density expanded styrene foam boards,
    closed-cell spray polyurethane foam insulation,
    and fiberglass or mineral wool  insulating drainage
    panels have been successfully used to insulate
    outside surfaces of foundation  walls.
  • Extend the insulation from the top of the  footing
    to the top of the sub-floor.
  • Specify protective covering for the above-grade
    portions of exterior insulation (e.g., stucco on
    stainless steel lath).
• When insulating on the inside of  foundation walls:
  • Specify a layer of foam board or closed-cell spray
    polyurethane foam insulation against the  interior
    side  of the basement wall  to keep warm humid
    air away from the cool foundation.
  • Specify an insulating value for the foam layer
    high enough to meet the ASHRAE Standard 90.1
    requirements, or specify a combination of foam
    insulation and,  on the foundation wall, moisture-
    tolerant insulation in the wall cavity (e.g.,
    fiberglass or mineral wool). The combination  of
    foam and fiberglass insulation  meets the required
    R-value, prevents condensation and allows the
    assembly to dry to the interior  (See Figure 2-3).
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Figure 2-3 Illustration of Basement Foundation Showing Drainage and Damp Proofing Only
                               Sloped lopsoil cap
                              Concrete foundation
                              wall

                              Damp proofing
                              (capillary break)
                              Geotechnig filter
                              fabric


-r


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• For vented crawl spaces:
  •  Specify one or more layers of insulation in the
     floor system between the crawl space and the
     first floor to achieve the insulation  levels required
     by ASHRAE Standard 90.1.  NOTE: Mechanical
     equipment cannot be located in vented
     crawlspaces. Specify air-sealing details to provide
     a  continuous air barrier from the above-grade wall
     across the floor between the  crawl  space and the
     first floor. Use the pen test (See Appendix A) to
     trace the continuity of the air barrier. NOTE: The
     air barrier for the foundation is part of  the whole
     building air barrier system.
  •  Specify a whole building air  leakage rate when
     tested at 75 Pascal  pressure difference in
     accordance with ASTM E779-10 Standard  Test
     Methods for Determining Air Leakage Rate  by
     Fan Pressurization or ASTM  £1827-96(2007)
                                    Standard Test Methods for Determining
                                    Airtightness of Buildings Using an Orifice Blower
                                    Door.  For example, the  U.S. Army Corps of
                                    Engineers requires a maximum air leakage rate of
                                    0.25 cubic feet per minute at 75 Pascal pressure
                                    difference.
                                  • A plastic or elastomeric membrane can be used
                                    instead of a concrete slab to form a capillary
                                    break and prevent evaporation from the soil
                                    into the crawl space. Concrete slabs are more
                                    durable, provide a solid  floor for the contractor
                                    to work from, and block the entry of burrowing
                                    rodents; however, membranes are less expensive
                                    and easier to install.
                                  • Provide screened vents to meet the International
                                    Building Code requirements for ventilated crawl
                                    spaces (Section  1203.3.1).
Figure 2-4 Components of an Unvented Crawl Space Foundation
                         Sealant

                         Flashing

                         Rigid insulation

                         3/8' fibercemenl board.
                         all surfaces coated
                         Ground slopes away
                         from wall at 5%
                         (6 inch per 10 foot)
                         Damp proofing
                         Filter fabric
Coarse gravel   \
(no fines)       '

Perforated drain
                                                                    Cavity insulation

                                                                    Sill gasket
                                           Protective membrane strip

                                           Concrete foundation wall

                                           Sealant

                                           Treated wood nailer

                                           Continuous polyethylene
                                           vapor barrier or air barrier
                                           (all joints  taped)



                                           Damp proofing
                                                                   Capillary break over footing
                                                                   (damp proofing or membrane)
                                                       Concrete fooling
                                                       below frost depth
Source: Conditioned Crawlspace Performance, Construction and Codes, Building Science Corporation (http://www.buildingscience.com/
documents/bareports/ba-0401-conditioned-crawlspace-construction-performance-and-codes). Accessed November 6, 2013.

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Verification of Foundation Design
• Write a description detailing how the foundation
  system manages rain and surface and sub-surface
  water. This typically would be located in the basis-
  of-design document.
• Provide details of sub-surface drainage systems in
  construction documents.
• Use the pen test (See Appendix A) to verify
  elements of the drainage system and the continuity
  of the capillary break from the intersection of
  the foundation with the first floor walls, around
  the foundation wall footing, to the center of the
  foundation.
• Provide two-dimensional sectional drawings where
  two materials that form the rainwater control come
  together and three-dimensional drawings where
  three or more elements of the rain protection
  system come together.
• Provide a list of critical details and an inspection
  schedule for the drainage and capillary break
  elements of the foundation that identifies the
  sequence of inspections, the parties  responsible for
  the inspections,  and the required documentation of
  the inspection results.
• Provide a list of inspection and maintenance
  requirements for the foundation drainage system.
• Write a description detailing how the foundation
  system manages water vapor during cooling and
  heating modes, as applicable.  Prepare drawings
  and specifications that detail water vapor migration
  control and the permeability and insulating values
  for all materials.
• Provide two-dimensional sections where two
  materials that  form the air barrier, insulation layer
  and water vapor control intersect.  Provide three-
                             www.epa.gov/iaq/moisture
  dimensional drawings where three or more elements
  of the air barrier, insulation layer and water vapor
  control intersect.
• Specify a fan pressurization test in design
  specification documents to assess the entire
  building enclosure using ASTM E779-10 Standard
  Test Method for Determining Air Leakage Rate by
  Fan Pressurization. Or ASTM £1827-96(2007)
  Standard Test Methods for Determining Airtightness
  of Buildings Using an Orifice Blower Door.
  • Specify when the test should be conducted in
    relation to the completeness of the air barrier
    system.
  • Identify the appropriate testing party.
  • Specify how the results should be documented,
    judged and accepted or rejected.
  • Specify the remedies if  the building fails the test.
• Specify quality  assurance  programs for the
  installation of the hygrothermal control elements of
  the  enclosure. Provide a list  of critical details and
  an inspection schedule for the air barrier, insulation
  layer and water-vapor-control elements of the
  foundation. Specify the sequence of inspections,
  the  parties responsible for the  inspections and the
  required documentation of the inspection results.
• Provide a list of inspection and maintenance
  requirements for the interior finishes if they are
  critical to water vapor control.  For example, if water
  vapor control  depends on a vapor-permeable interior
  finish,  low-perm vinyl wall coverings and paints
  should be avoided during renovations. Pictures,
  blackboards and mirrors should be spaced off the
  wall.
• Specify, in the control guide for the building
  operators, the maximum dew point levels allowed in
  the  interior of basements and crawlspaces.
                                                   37

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www.epa.gov/iaq/moisture
Issue
Moisture control is an important aspect of designing
an integrated building enclosure. Failing to properly
design walls to manage  moisture and failing to
integrate moisture management system features
with those of other building enclosure components,
such as the roof and foundation, can lead  to serious
moisture-related damage. Correcting problems
resulting from poorly designed walls can necessitate
the replacement of multiple building components
leading to high repair costs.

Goals

Wall Design Goal 1: Design exterior walls to manage
rainwater.

Wall Design Goal 2: Design exterior walls to prevent
condensation of water vapor on cool surfaces within
the dry portion of the exterior wall assembly, on the
inner surface of the exterior walls or within the interior
wall, floor or ceiling cavities.

Guidance

Wall Design Goal 1: Design exterior walls to manage
rainwater.

Guidance 1: Design walls to protect their inner
portions from direct rain and seepage through the
cladding.
• Design walls that have rainwater protection behind
  the cladding in the form  of air gaps and barrier
  materials (i.e., the drain  plane) to keep water from
  wicking further into the wall.
• Specify in the design  drawings and specifications
  the flashing of penetrations—including windows,
  doors and roof-wall intersections—to a designated
  drain plane.
• Provide sections and specifications detailing
  flashing for all wall penetrations.  Flashing for larger
  penetrations (e.g., windows, doors and exhaust
  and  intake grilles) must be carefully  designed and
  detailed. At the top, flashing must extend from
  beneath the drain plane material, across the top
  of the trim, and out past the siding and trim (See
  Figures 2-6 and 2-7). The bottom  must have a
  pan flashing with  end dams and a  back dam. Side
  flashing must cover the rough opening and extend
  beneath the drain plane on the wall and flash down
  over the end dams on the sill flashing.
• Among the most common problem areas for
  flashings in walls  are:
  •  Windows.
  •  Doors and trim.
  •  Outdoor air intakes, exhaust outlets and fans.
  •  Ducts, pipes and electric conduit entries and
     exits.
  •  Through-wall flashings where a horizontal
     element (e.g., roof) intersects the wall of a taller
     portion of the building. Similar locations include
     exterior stairway-wall intersections as well as
     relieving angles, awning  decks, and balcony
     and  plaza intersections with the wall of  a taller
     section of building (See  Figure 2-8.)

Wall Design Goal 2: Design exterior walls to  prevent
condensation of water vapor on cool surfaces within
the dry portion of the exterior wall  assembly, on the
inner surface of the exterior walls or within the interior
wall, floor or ceiling cavities.

Guidance 1: Design walls to be sufficiently airtight to
limit water  vapor migration by air flow.

Specify air-sealing details to provide  a continuous air
barrier from the roof-wall intersection to the  above-
grade wall-foundation intersection. Use  the pen test
(See Appendix A) to trace the continuity of the air
barrier. NOTE: The air barrier for the walls is part
of the whole building air barrier system. Specify a
whole building air leakage rate when tested at 75
Pascal pressure difference in  accordance with ASTM
E779-10 Standard Test Methods for Determining Air
Leakage Rate by Fan Pressurization or ASTM E1827-
96(2007) Standard Test Methods for Determining
Airtightness of Buildings Using an Orifice Blower
Door. For example, the U.S. Army Corps of Engineers
                                                    38

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requires a maximum air leakage rate of 0.25 cubic
feet per minute per square foot of air barrier surface
when  measured at a pressure difference of 75 Pascals
between indoors and outdoors. The air barrier surface
area includes all six surfaces of the barrier: top,
bottom and all four sides.
• Select a layer of material in the wall assembly to
  form the basis of the air barrier systems.  Interior
  gypsum board, foam board or spray foam insulation,
  concrete, and oriented strand board (OSB) or
  plywood deck are good choices for the basis of
  air barrier systems in wall  assemblies. Include
  specifications for all accessory materials required to
  provide durable continuity of the air barrier.
• Provide sections and specifications detailing
  methods for providing air barrier continuity,
  especially at penetrations, corners and edges:
  • At penetrations through the air barrier layer (e.g.,
    rough openings for windows, doors, pipes, shafts
    and conduits).
  • At transitions  between one air barrier material
    and another (e.g., wall-ceiling intersections and
    wall-floor intersections).
  • Where the air  barrier must pass around structural
    elements (e.g., heavy steel construction must
    be carefully detailed where the exterior walls
    encounter vertical steel  posts or horizontal
    beams).
• Provide sections highlighting the air barrier and
  connecting materials and methods from the center
  of the roof to the center of the  foundation for each
  section.

Guidance 2: Meet  or exceed  the R-value for walls
as described in the 2012 International Energy
Conservation Code.
• Provide two-dimensional sections detailing methods
  for providing insulation layer continuity:
  • At windows, doors, columns, conduits and other
    penetrations through the air  barrier layer.
  • At transitions  between one insulating material
    and another (e.g., where roof insulation meets
    wall insulation).
  • At thermal bridges in the insulation layer (e.g.,
    where steel  members penetrate the insulation
    layers).

Guidance 3: Design walls to  manage heat flow and
vapor  diffusion to avoid condensation in the wall
assembly and to dry toward the interior, exterior
or both. Designers  may provide details about the
                             www.epa.gov/iaq/moisture
continuity of the air barrier and the insulating layers
at penetrations and intersections.

Option 1:  Follow published regulation or guidance on
combining insulation, air barriers and the permeability
of materials for walls to control condensation (See
references Chapter 2). Examples include:
• The 2012 International Building Code and
  International Residential Code.
• High Performance Building Enclosures by
  Straube (2011) provides systematic guidance for
  condensation control in four types of roof and wall
  assemblies for all North American climates.
• Understanding Vapor Barriers by Lstiburek
  (ASHRAE August 2004) applies to all climate zones
  (See Figures 2-9 through 2-12).
• The Building Envelope Design Guide on the Whole
  Building Design Guide website includes brick and
  stone veneer and  curtain wall systems.
• The Canadian Mortgage and  Housing Corporation
  Best Practice Guides apply to climate zones 6 and 7.

Option 2:  Model the performance of proposed wall
assemblies using a hygrothermal software program
(e.g., WUFI or hyglRC). Use design conditions from
ASHRAE Standard 160P for modeling.  Note, however,
that the results of computer simulations should
be interpreted cautiously and in light of real-world
construction practices. For example,  most computer
models assume that walls are airtight and that no
water vapor is transported through them by  airflow.
Therefore, for the model to be  valid, the assembly
must be designed,  installed and tested to meet air
tightness standards. Also, the  performance  of  any
assembly depends on its  orientation in  regard  to solar
load and wind direction during heavy rains.  Some of
the programs can model the dynamic of rainwater
absorbed by porous claddings  and vaporized into the
assembly by the sun,  but others cannot.

Guidance  4: Design brick and  masonry-clad walls to
prevent the rain-sun-driven water vapor dynamic.
• If the cladding is brick or concrete masonry units
  and the wall is insulated with high-permeability
  (perm >10) porous insulation and located in
  climate zones 1, 2, 3, 4 or 5 (See  Figure 2-5):
  • Back-vent the cladding.
  • Use  low-permeability (perm <1)  insulating
    sheathing and interior finishes with perm >2.
  • In climate zones 1, 2 and 3, design the building
    to operate at positive pressure.


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www.epa.gov/iaq/moisture
Figure 2-5 The International Energy Code Climate Zone Map Developed by the U.S. Department of Energy
    Marine (C)
    PurUjnd
    All of Alaska in Zone 7 except for the following Boroughs in Zone 8: Bethel. Dellirkgham, Fairbanks. N. Star, Nome North Slope, Northwest Arctic. Southeast Fairbanks, Wade Hampton, and
                                          Yukon-Koyukuk
    Zone 1 includes: Hawaii, Guam, Puerto Rico, and the Virgin Islands
Verification of Wall Design
  Write a description detailing how the wall system
  manages rain. Include this description in the basis-
  of-design document.
  Use the pen test (See Appendix A) to verify the
  continuity of the drain plane from the intersection
  with the roof, through flashings, and around
  penetrations to the foundation.
  Provide two-dimensional sections where two
  materials that form the rainwater control come
  together and three-dimensional  drawings where
  three or more elements of the rain protection
  come together. Sections must show continuity of
  capillary breaks and flashing around penetrations
  and interface with air barrier and  insulation systems
  (See Figure 2-8).
  Specify a quality assurance (QA) program for
  installation of the rainwater protection systems.
  At a minimum, provide a list of  critical details, an
  inspection schedule and quality assurance tests of
  the drainage and capillary break elements of the
  wall systems. Specify the sequence of inspections
and tests, the parties responsible for them and
the required documentation of the results. Parties
involved in QA may include subcontractors, general
contractors, commissioning agents and independent
third-party inspection or testing providers. Provide  a
list of inspection and maintenance requirements for
the exterior cladding, flashings and drain plane.
Use wall assemblies detailed in guidance or
journals that have been designed to  manage
water vapor and condensation for the climate of
interest. Perform hygrothermal modeling when
no documentation through previous testing or
modeling of a wall assembly in a particular climate
is available.
Write a  description detailing how the wall system
manages water vapor during cooling and heating
modes,  as applicable. Prepare drawings and
specifications that detail water vapor migration
control  and the permeability and insulating values
of all  materials.
Use the pen test (See Appendix A) to verify
the continuity of the insulation layers and air
barriers from the intersection with the roof,
                                                     40

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  through flashings, and around penetrations to the
  foundation.
• Provide two-dimensional sections where two
  materials that form the insulation layers and air
  barrier come together and three-dimensional
  drawings where three or more elements of the
  insulation and  air barrier come together.
• Specify in the design specification documents a
  fan pressurization test to assess the entire building
  enclosure in accordance with ASTM E779-10
  Standard Test Method for Determining Air Leakage
  Rate by Fan Pressurization, ASTM E1827-
  96(2007)Standard Test Methods for Determining
  Airtightness of Buildings Using an Orifice Blower
  Door of the U.S. Army Corps of Engineers Air
  Leakage Test Protocol for Building Envelopes.
  •  Specify the target airtightness level.
  •  Specify when the test should be conducted  in
     relation to the completeness of the air barrier
     system.
  •  Identify the appropriate testing party.
                              www.epa.gov/iaq/moisture
  • Specify how the results should be documented,
    judged and accepted or rejected.
  • Specify the remedies if the building fails the test.
• Provide a list of critical details, an  inspection
  schedule and  QA tests for the air barrier, insulation
  and vapor control  elements of the walls. Specify
  the sequence  of inspections and tests, the parties
  responsible for them, and required documentation
  of the results.
• Specify QA  programs for the installation of the
  hygrothermal control  elements of the enclosure.
  Provide a list of inspection and maintenance
  requirements for the  interior finishes if they  are
  critical to water vapor control (e.g., if water vapor
  control depends on a vapor-permeable interior
  finish, then low-perm vinyl wall-cover ings and
  paints should  be avoided during renovations;
  pictures, blackboards and mirrors should be spaced
  off the wall).
• Specify maximum dew points to be maintained in
  conditioned spaces during the heating and cooling
  seasons.
Figure 2-6 Section Illustrating Window Flashing and Jamb Flashing for Stone Veneer Wall
                                                                      Insulating element (foam board or
                                                                      spray polyurethane foam)
                                                                      Drain plane - WR8. self-adhered
                                                                      membrane
                                                                      Back-up wall
                                                                      Exterior-grade (glass-mat shown)
                                                                      sheathing. All joints sealed with
                                                                      self-adhesive membrane
                                                                      Mortar drainage mesh
                                                                      Clay brick masonry with vented
                                                                      weep (minimum one every 2-feet)
                                                                      at window head flashing
                                                                      Corrosion-resistant metal head
                                                                      flashing with integral end-dams
                                                                      Self-adhered membrane window
                                                                      flashing
                                                                      Thermally broken glazing system
                                                                      with Insulating glass unit
                                                     41

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www.epa.gov/iaq/moisture
Figure 2-7 Section Illustrating Pan Sill Flashing and Jamb Flashing For Brick Veneer Wall
                                 Insulslod nwlal (ram* wall
                                 Closure amp flaUwi to
                                 idf-adhefftd membrane
                                 Flashing typ*
                                 interior flaflhinj teg end tidy
                                 sealed end-dams
                                 Wall drannga plftn* - conteOM
                                 dram pteneJa* banw
Figure 2-8 Detail  Illustrating Through Flashing Where a Lower Roof Intersects a Wall
                                                                                    Brfckwtf
                                                                                    A* I vepa Otalf m»n*rwi».
                                                                                         tsmn-ijd Ultulfloil
                                                                                    adherwJ ID *f?vapw bamer
                                                                                    •nd onr M
                                                                                    P^mmjto Nl»f lutmc
                                                                                    RQUrauWUn

                                                                                    Roofing ni^iTtbiviv

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                                                                                        www.epa.gov/iaq/moisture
Figure 2-9 Concrete Block with Interior Rigid Insulation and Stucco
II

f^nnrmtfL Klsvlr 1
Rigid insulation (vapor semi-permeable)
- unfaced extruded polystyrene, unfaced
expanded polystyrene, fiber-faced
isocyanurate
Metal channel or wood furring


.
.

Latex paint or vapor semi-permeable
textured wall finish
^l^l^^l
' > -
. *
^
.
v *>
-
•*• i
f t
:
•W 3
*
^ " i,
» ••
' *
' t
• »
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~

:
^
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ta
„-
                                                                        I
                                                                  Vapor Profile
Figure 2-10 Concrete Block with Interior Rigid Insulation Frame Wall with Cavity Insulation and Stucco

Stucco rendering •-

Concrete block
- unfaced extruded polystyrene, unfaced
expanded polystyrene, fiber-faced
isocyanurate
Insulated steel or wood stud cavity

*

IP"
batts. spray-applied cellulose or
spray-applied low density foam)
i

Latex paint or vapof S8rni-permeable
u


^^^•^^^
.
«• i
»
-
V -•
• 1
- - t

• »
-, A

m


»
•
-
-»
•

                                                                         I
                                                                         I
                                                                   Vapor Profile
                                                       43

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www.epa.gov/iaq/moisture
Figure 2-11  Frame Wall with Exterior Rigid Insulation with Cavity Insulation and Brick or Stone Veneer
Brick veneer/stone veneer — •
Exterior rigid insulation - extruded
polystyrene, expanded polystyrene,
isocyanurate, spray polyuretharte foam.
rock wool, fiberglass
Membrane or trowel-on or spray-applied
vapor banter (Class 1 vapor retarder), air
barrier and drainage plane (impermeable)
sheathing, plywood or OSB
Cavity insulation (unfaoed fiberglass
batts, sprayed-applied cellulose or
spray-applied tow density foam)
Latex paint or vapor semi-permeable
	 »
=
i
• «-
^
                              textured wall finish
                                                                   Vapor Profile
Figure 2-12 Precast Concrete with Interior Spray-Applied Foam Insulation
LdlBA pail I!
Spray-applied low density or high
density foam insulation

Latex paint or vapor semi-permeable
textured wall finish
, *fc . A
•
,
.
«
- i»
' > . ' 9 .
* I*
s *• , A
'-•>'.'<
. f-
f,.
;'t\'l'

i

*
                                                                         Vapor Profile
                                                       44

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  Roof  and Ceiling Assemblies
                                                                                  www.epa.gov/iaq/moisture
Issue
Improper detailing of the roof and ceiling assemblies
may result in unwanted water intrusions or
condensation problems that can lead to damage to
the building and its contents. Failure to properly
design the roof can result in  more frequent and costly
roof maintenance or repairs and a shorter building
lifespan. In roof-and-ceiling assemblies, the rain
water control portion of the roofing system may be
separated from insulation and air barrier layers by
a vented attic space. In this case, rainwater control
continuity is traced through the roofing system,
while air barrier and insulation continuity may be
traced at ceiling level. In this section, the term roof
assembly refers to the entire assembly that provides
rain protection, thermal  insulation, air  barriers and
condensation control.

Goals

Roof and Ceiling Assembly Design Goal 1: The roof
collects and disposes of rainwater.

Roof and Ceiling Assembly Design Goal 2: Roof
assemblies are designed to prevent condensation of
water vapor on cool surfaces within the dry portion
of the roof assembly, on the interior surface of the
exterior roof assembly or within the interior wall, floor
or ceiling cavities.

Roof and Ceiling Assembly Design Goal 3: The roof
design considers maintenance for moisture control.

Guidance

Roof and Ceiling Assembly Design Goal 1: The roof
collects and disposes of rainwater.

Guidance 1: Slope the roof to drain rainwater toward
collection and disposal sites.

Determine roof slope, or pitch, based on ordinary
use and design requirements. For example, for safety
purposes a  roof that serves as a plaza,  garden area,
or other social space must have a slope low enough
  Slopes and Typical Roof Coverings

  • Low-slope roof coverings:
    • Built-up roofs.
    • Modified bitumen.
    • Single-ply.
    • Sprayed polyurethane foam.
    • Metal panels.

  • Steep-slope  roof coverings:
    • Metal panels and shingles.
    • Asphalt shingles.
    • Slate.
    • Tile.
to be safe. Slightly higher slopes can be tolerated for
limited-access roofs where mechanical equipment
that requires routine inspection and servicing is
located, but the slope of these roofs still  must be
low enough to allow safe walking. Higher roof pitch
may be selected for visual appeal, consistency with
surrounding buildings or for the ability to shed snow
or rain. Roofing materials selected for appearance or
performance may  have minimum slope requirements.
For example, slate roofs should  not be less than  or
equal  to a 3-in-12 pitch  (3:12), while some low-slope
roof membranes have  been used on essentially flat
roofs.  For these materials, this guidance requires at
least a lA-'m-12 pitch  (1A:12) to promote positive
drainage  in the face of deflection and construction
tolerances. Even "flat" roofs  should be sloped.

• Use roofing materials that  are appropriate for the
  pitch. Select roofing material  in accordance with
  the  requirements of the Whole Building Design
  Guide for low-sloped and steep-sloped  roofs.
  NOTE:  Low-sloped  roofs are defined as roofs with
  a slope less than or equal to 3:12 (25 percent).
  However, with the exception of metal roofs, most
  low-slope roofs  must have  a minimum slope of
  1A-.12 (2 percent). Steep-slope roofs are defined
  as roofs whose slope is greater than 25 percent.
  Some materials can be used on both low and steep
  slopes, while others are limited to either  low or
  steep slopes.
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• Design site water collection and disposal systems to
  provide positive roof drainage where:
  • All loading deflections of the roof deck are
    considered.
  • Local rainfall rates are considered.
  • The roofing manufacturer's drain placement
    requirements are followed.
  • Roof drainage within a maximum of 48 hours
    after precipitation is ensured.

Guidance 2: Design the roof drainage system with
sufficient runoff-handling capacity.

The amount of water  to be handled depends on
the area and slope of the roof and the intensity of
rainfall at the building site. Chapter 11 of the 2003
International Plumbing Code (IPC), Storm Drainage,
requires that the size of vertical conductors and
leaders, building storm drains, building storm sewers,
and any horizontal branches of such drains or sewers
be based on the 100-year hourly rainfall rate. Use
figures presented in that chapter or rainfall rates
derived from approved local weather data.

The building's design, appearance and location
influence the type of  roof drainage system. Designers
may opt to  use external drainage systems, internal
drainage systems or both.

External Gutter and Downspout Drainage Systems

Design external gutter and downspout roof drainage
systems in  accordance with Chapter 1 (Roof Drainage
Systems) of the Sheet Metal and Air Conditioning
Contractors' National Association, Inc. (SMACNA)
Architectural Sheet Metal Manual. The SMACNA
manual provides guidance for sizing drainage
systems for 10-year and 100-year storms. Compare
net drainage capacity of design with local code
requirements.
• Size gutters and downspouts to effectively drain
  maximum runoff by determining the amount of
  water the drainage system  must handle given the
  area of the roof to be drained, its pitch, and the
  rainfall intensity. For specific information, seethe
  SMACNA Architectural Sheet Metal Manual or the
  IPC requirements referenced  in this section.
• Connect  all downspouts to sloped leaders, with  a
  5 percent—6 inches per 10 feet—minimum slope
  that extends at least 10 feet from the foundation or
  that meets more stringent local code requirements.
  Leaders may be placed either above or below
  ground.
• For below-ground or above-ground leaders, use
  materials conforming to the standards listed in
  the IPC. Ensure that seams and joints in leaders
  are watertight to prevent water from escaping  next
  to the foundation. In order to prevent root growth
  within  below-ground leaders, ensure that the
  leaders are not perforated.
• If above-grade leaders are used, provide protection
  from accidental damage or encroachment.
• Direct all leaders to code-approved disposal,
  typically daylight, drywells, swales or ponds. But in
  buildings making efforts to reduce rainwater runoff,
  rainwater may be collected for  use  in building
  operations. Proper disposal  prevents potentially
  contaminated storm water from adversely affecting
  water quality.
• In climates with  significant snowfall,  design the
  roof assembly to avoid ice dams on roofs that  drain
  to external gutter systems. See Roof and Ceiling
  Assembly Design Goal 4 guidance.

Internal Roof Drainage Systems

Internal roof drainage systems consist of drains on the
roof surface connected to down pipes running through
the building's interior and leading to storm sewers or
other discharge points. Internal roof drainage systems
are the most practical solution for large, low-slope
roofs. They are resistant to ice dam problems on low-
slope roofs in areas of significant snowfall because
the drains are warmed by the down pipes passing
through the building. Internal drainage  systems  are
seldom used on high-slope roofs (greater than 3:12).
Figure 2-13  illustrates interior drain placement for a
low-slope roofing system.
• Size and locate drains to  remove maximum
  rainwater and snowmelt flows effectively. Refer to
  IPC Chapter 11,  Storm Drainage.
• Ensure that features such as superstructures and
  roof-mounted HVAC units do not obstruct the flow
  of water from the roof to the drain.
• Equip roof drains with strainers or other devices to
  prevent leaves and other debris from  clogging the
  drain or the down pipe.
• Locate drains at  the center of bays between
  columns so that  any structural  deflection will
  produce slopes to the  drain.  Provide allowance in
  the leader connection  for any vertical movement
  resulting from the structural  deflection.
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Figure 2-13 Plan Drawing Illustrating Interior Drain Location and Roofing Slope for a Low-Slope System

              Perimeter wind-uplift
              zone
              Comer wind-uplift
              zone
                           Upper roof

                           Corner wind-uplift
                           zone


              Corner wind-uplift
              zone
    Area divider curb
Comer wind-uplift

                                                                                   zone
                                            LEGEND:

                                              *  Roof drain
                                              O  Overflow drain
• Design all roofs with at least a 1A-.12 pitch
  to overcome low spots caused by expected
  roof member deflection or construction within
  tolerances.
• Locate down pipes in interior chases.  Down pipes in
  chases along exterior walls are more vulnerable to
  condensation.
• Allow easy access to down pipes for periodic
  inspection and repair by providing access panels or
  utility closets.
• For parapets or other architectural protrusions
  above the roof line, provide a secondary method
  for draining rainwater if the primary roof drainage
  system does not function. Two methods are often
  used:
  •  The installation of scuppers through the parapet.
  •  The installation of an additional system of  roof
     drains and down pipes.
Guidance 3:  Design penetrations parapets and
roof and wall intersections to prevent the entry of
rainwater. Figures 2-14, 2-15 and 2-16 illustrate
rainwater control details for a gooseneck vent
penetrating a low-slope roof and for a low-slope roof
intersecting a parapet wall.

Drainage layers must maintain  integrity at joints
and penetrations, where the enclosure is the most
susceptible to moisture problems. See Table 2-1 for
a list of penetrations commonly found in roofs and
for guidance  on  how to  maintain  integrity at those
penetrations.
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Figure 2-14 Three-Dimensional Drawing Detailing Rainwater Control Continuity at Intersection of Goose Neck Vent,
Flashing and Roofing Membrane
          Prefabricated stainless steel
          goose neck vent (cutaway)
          Granular surfaced modified
          bitumen flashing
          Granular surfaced modified
          bitumen cap sheet

          Tapered insulation
          Concrete topping
          (If applicable}
                                               Sheet metal sleeve
                                               Roof cement cove at base
                                               of penetration
                                               Modified bitumen base sheet
                                                                                  Structural concrete deck
                                              Set bottom flange ol goose
                                              neck vent in bed or maslic
Table 2-1 Maintaining the Integrity of Drainage Layers at Joints and Penetrations
NOTE: Continuity of the air barrier and insulation layer must also be maintained at these locations.
 Common Roof Penetrations
 Joints between roofing materials
 Roof edges
 Joints between the intersection
 of walls and roofs
 Skylights and roof hatches
 Chimneys
 Air  handlers and exhaust fans
 Outdoor  air intakes and passive
 relief vents
 Plumbing vents
Ways to Maintain Integrity of Rainwater Protection
Provide continuity by shingling or sealing
Provide capillary breaks by using overhangs, copings and drip edges
Provide continuity by using flashing where a lower story roof intersects a
wall of a higher  level  and where the roof meets the wall of a dormer
Provide continuity by using flashing, curbs and counter-flashing
Provide continuity by using flashing, crickets and counter-flashing
Provide continuity by using flashing, curbs and counter-flashing
Provide continuity by using flashing and counter-flashing
Provide continuity by using flashing and counter-flashing
                                                        48

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Roof and Ceiling Assembly Design Goal 2: Design
roof assemblies to prevent condensation of water
vapor on cool surfaces within the  dry portion of the
roof assembly, on the interior surface of the exterior
roof assembly or within interior wall, floor or ceiling
cavities.

Guidance  1: Design the roof and ceiling assembly to
be sufficiently airtight to  limit water vapor migration
and heat transfer by air flow.
• Specify air-sealing details to provide a continuous
  air barrier from the center of the roof-and-ceiling
  assembly to the roof-wall intersection. Use the pen
  test (See Appendix A) to trace the continuity of the
  air barrier.  NOTE: The air barrier for the roof is part
  of the whole building air barrier system.
• Specify a whole building air leakage rate when
  tested at 75 Pascal pressure difference  in
  accordance with ASTM E779-10 Standard Test
  Method for Determining Air Leakage Rate by Fan
  Pressurization or ASTM £1827-96(2007) Standard
  Test Methods for Determining Airtightness of
  Buildings Using an Orifice Blower Door or the U.S.
  Army Corps of Engineers Air Leakage Test Protocol
  for Building Envelopes. For example, the U.S. Army
  Corps of Engineers requires a maximum air leakage
  rate of 0.25 cubic feet per minute per square
  foot of air barrier surface (6 sides) at a pressure
  difference of 75 Pascals.
• Use a layer of  material  in the roof or ceiling
  assembly as the basis of the air barrier systems:
  • Interior gypsum board, foam  board or spray
    foam  insulation, concrete, and OSB or plywood
    deck  are good selections to form the basis of
    air barrier systems in roof assemblies. Include
    specifications for all  accessory materials required
    to provide durable continuity of the air barrier.
  • Fully  adhered roofing membranes can be used to
    make the air barrier  in non-vented low-slope roof
    systems.
  • Fluted steel deck is difficult to use as the basis
    of an  air barrier. (The flutes are difficult to air-
    seal at the perimeter and joints.)
  • A suspended T-bar ceiling—clipped or not—
    cannot be used  as an air barrier system.
• Provide  two-dimensional sections detailing methods
  for providing air barrier continuity at pipes, shafts,
  skylight vaults, light fixtures, conduits and other
  penetrations through the air barrier layer (See Table
  2-1).
                             www.epa.gov/iaq/moisture
• Provide two-dimensional sections highlighting the
  air barrier and connecting materials and methods
  for each section.

Guidance 2: Select the overall insulation R-value to
meet or exceed ASHRAE 90.1 or International Energy
Conservation Code requirements.
• Provide two-dimensional sections detailing methods
  for providing insulation layer continuity:
  • At pipes, shafts, skylight vaults, light fixtures,
    conduits and other  penetrations through the air
    barrier layer (See Table  2-1).
  • At transitions between one insulating material
    and another (e.g., where roof insulation meets
    wall insulation).
  • At thermal bridges in the  insulation layer (e.g.,
    where steel members penetrate the insulation
    layers).

Guidance 3: Collect the air barrier, the insulation
layer and the materials with  the lowest water
vapor permeability (<2 perms) into an assembly of
consecutive, touching layers. NOTE: This does not
include the roofing or roof sheathing. Roofing and
sheathing may be in contact with these layers—non-
vented roof assembly—or separated by a space that
vents to the outdoors—vented  roof assembly. Figures
2-17 and 2-18 illustrate condensation control in two
non-vented low-slope roof systems.

Step 1: Determine whether to  use a vented  or non-
vented roofing system based on climatic and space-
use considerations.
• Do not place mechanical equipment in vented attic
  space.
• Condensation on roof  bottom sheathings that  results
  from night sky radiation is most easily avoided by
  using unvented roof assemblies.
• Non-vented roofing  is  more resistant to fire caused
  by wildfire embers.

Step 2: Collect all the materials with low water vapor
permeability (< 2 perms) together on one side of any
vapor open cavity insulation  layer. NOTE: Vented roof
and ceiling assemblies separate low-permeability
materials in the roofing-sheathing layer from low-
permeability materials in the ceiling, air barrier  and
insulation layers by a vented space between them.
Both the roof and ceiling assemblies can dry to  this
space. Apply either Step 3A  or Step 3B.
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Step 3A: Follow published guidance on combining
insulation, an air barrier, and materials of appropriate
permeablility for vented and non-vented roofing
systems in the relevant climate zone.19 Depending on
the insulation systems selected, apply the following
specific guidance.

If using insulation composed entirely of low-
permeability foam insulation (e.g., closed-cell spray
polyurethane foam or foam board insulation), note
that:
• Spray foam provides an inherent air barrier,
  insulation layer, and vapor control for all climates.
  It still requires specific detailing at transitions
  between the spray foam and adjoining assemblies.
• Foam board provides insulation and vapor
  permeability control but requires air-sealing
  details at the joints, penetrations and roof-wall
  intersection. This can be achieved using a separate
  air barrier system (e.g., wood panel or gypsum
  board roof deck sealed to provide the air barrier) or
  using the foam board as the basis of the air barrier.

Caution:  In special high-moisture areas (e.g., indoor
swimming pools) using closed-cell spray polyurethane
or foam board insulation,  non-vented low-slope roofs
may need a vapor retarder with a lower perm rating
than that of the roofing membrane. Special  analysis is
needed for high  internal moisture load uses (See Step
3B). If using all  open-cell spray foam (Yz Ib./cu. ft.
spray):
• Foam provides an  inherent air barrier.
• Separate interior vapor control  is required in
  climate zones 5, 6 and 7.
  • Put materials (except roofing materials) with
    perm <2 and the air barrier on the interior side of
    the insulation layer.
  • Use interior class II  or III vapor barrier.
• Applies to vented and non-vented  roofs.

If using all high-perm porous insulation (e.g.,
fiberglass, cellulose) for non-vented roofs:
• Use  only in hot, dry climates.
• A separate air barrier system is required.

If using all high-perm porous insulation (e.g.,
fiberglass, cellulose) for vented roofs:
• A separate air barrier system is required.
• Separate water vapor control is required in climate
  zones 5, 6 and 7.
  •  Put materials with perm <2 (except roofing
     materials) and the air barrier on the interior side
     of the insulation layer.
  •  Use interior class I or II  vapor barrier in climate
     zones 6 and 7.
  •  Use interior class III  vapor barrier in climate zone
     5.
  •  In all milder climate  zones, put the air barrier on
     the inside or outside  of the insulation layer. Use
     no materials less than 2 perms in the assembly
     —excluding roofing.

If using a layer of high-perm  insulation and a  layer of
low-perm  insulation together for non-vented roofs:
• All the low-perm materials (<2 perms) including the
  foam insulation should  be  collected on the exterior
  side of the high-perm insulation layer.
• Closed-cell spray polyurethane foam insulation
  provides an inherent air barrier.
• Foam board insulation must have a separate air
  barrier (e.g., roof sheathing or roofing membrane
  or air-sealing details at  the joints, penetrations and
  roof-wall intersection).
• The temperature of the  condensing surface  should
  be controlled using a ratio  of low-perm R-value to
  high-perm R-value. For  ordinary indoor humidity
  conditions, at least one-third of the overall R-value
  should be  provided by the  foam insulation.

If using a layer of high-perm  insulation and a  layer of
low-perm  insulation together for vented roofs:
• All the low-perm materials (<2 perms) including the
  foam insulation should  be  collected on the  interior
  side of the high-perm insulation layer.
• Closed-cell spray polyurethane foam insulation
  provides an inherent air barrier.
• Foam board insulation must have air-sealing details
  at the joints, penetrations  and roof-wall intersection
  or a separate air barrier (e.g., roof sheathing or
  roofing membrane).

Step 3B: Model the performance of proposed  roof
assemblies using a hygrothermal software program
(e.g., WUFI  or hyglRC). Use  design conditions from
ASHRAE Standard 160-2009 for modeling. Note,
however, that the results of computer simulations
should be interpreted cautiously and in light of
 'See Straube (2011) for all climate zones, Lstiburek (ASHRAE April 2006) for all climate zones and CMHC Best Practice Guides for climate zones 6 and 7.


                                                     50

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                                                                                      www.epa.gov/iaq/moisture
Figure 2-15 Moisture Control in an Unvented Low-Slope Roof Assembly with Structural CMU Walls
                       Air barrier transition membrane wraps (op—|
                       of framing connecting roof ail barrier to
                       WB« »r terror (NOTE; At bsmef and rood
                       ing m*frtbf»n* products from Me roofing
                       f utKontndO' corn* in contact with air bV-
                       iiMf m*»ri»H ftorn the wall air hsrrwi sub.
                       contractor All matenals toucftng sach
                               Cavity iuubtion
                               SiHf adhff-ing roof air banter
                               membrane on concrete plank
                               and CMU parapet
                               Roofing membrane
                               oncaverboard
                                   dranag* plans mem-
                               brane on slruclural CMU wall
                               Masonry be embedded in
                               *bvdui*l CMU wall with
real-world construction practices. For example, most
computer models assume that walls are airtight and
that no water vapor is transported through them by
airflow. Therefore, for the model to be valid, the
assembly must be designed, installed and tested to
meet air tightness standards. Also, the performance
of any assembly depends on its orientation in regard
to solar load and wind direction during heavy rains.
Some, but not all, of the programs can model the
dynamic of  rainwater absorbed by porous claddings
and vaporized into the assembly by the sun.

Guidance 4: Control ice dams in climate zones 5, 6
and 7.
•  Provide a carefully detailed, tested air barrier in the
   roof system (See Guidance 2). Locate the air barrier
   in the same plane as or adjacent to the  insulation
   layer for all assemblies.
•  Drain non-vented, low-slope roofs to interior drains
   or use spray or board foam to insulate non-vented
   roofs that slope to eave drainage. The required total
   R-value can be met using foam insulation alone
   or by a combination of foam insulation and high-
   perm porous insulation materials (e.g., fiberglass,
   cellulose  or mineral wool). The foam insulation
   must be located in contact with, but outside of, the
   porous insulation.
  •  Or use vented roofs that slope to eave drainage
     and avoid sources of heat in vented attics and
     vented roof sheathing systems.

Roof and Ceiling Assembly Design Goal 3: Roof
design considers maintenance for moisture control.

Guidance 1:  Ensure that systems are easily
maintained and that maintenance plans are reviewed
with the owner.
• Materials in the roof and ceiling assembly that will
  be difficult or expensive to remove and replace
  must have an expected service  life at least as  long
  as the materials enclosing them.
• Design assemblies to shed rainwater by use of
  flashings and lapping  materials to drain. Do not
  depend on sealants  alone to control rainwater  entry
  in areas  that will be difficult or hazardous to inspect
  and  repair.
• Develop  or require the contractor to develop
  maintenance documents for the roofing systems
  including warranty requirements, scheduled
  inspections and maintenance, and appropriate
  repair processes.
• Develop  a plan for both surface and subsurface
  drainage that specifies:
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Figure 2-16 Moisture Control in an Inverted Membrane Roof with Heavy Steel Frame and Light Steel In-Fill
                             Air barrier transition (membrane wraps top a? —
                             framing connecting n»f air water and vapor
                             barf*** lo wall *>-&a*r*f (NOTE Rscfirxj
                             immbniM products bom the f«rf*>g sufccwv
                             tractor com* NH e&nwct wttti wall a* barrier
                             materials from the wall off barrier a-jtoanlrac-
                               Al rmtcnata louchtrg each other musl
                                  Fully adherwj rod »r. w»
                                  ang vapor &»™r m^mtwne
                                        S*IF-3dhenng wall J»r
                                        barner.'draifi*gfi plane mem-
                                        brane an g^pju.n
                                        bv Be*!-a<*»nn9 *al a*
                                        barmr
                                        Cavity luulafian


                                        Maadivy 5* wilfi reuinMg —J
                                        clc attached hrcugh j^H-
                                        healing air bamer and gyp-
   •  Maximum rainfall or snowmelt assumptions.
   •  Drainage surface areas including shapes, slopes,
     superstructures or other obstructions.
   •  Estimated water flows.
   •  The location and capacities of all  conduits.
•  Provide drainage system maintenance plan
   requirements.

Verification of Roof and Ceiling Assemblies

•  Write a description detailing how the roof system
   manages rain.  Include this description  in the basis-
   of-design document.
•  Use the pen test (See Appendix A) to verify the
   continuity of drainage surfaces, capillary breaks and
   flashing around penetrations from the center of the
   roof to the intersection with the exterior walls.
•  Provide two-dimensional sections where two
   materials that form the  rainwater control come
   together and three-dimensional drawings where
   three or more elements  of the rain protection come
   together. Sections must show continuity of capillary
   breaks and flashing around penetrations and
   interface with air barrier and insulation systems.
• Provide a list of critical details, an inspection
  schedule and quality assurance tests of the roofing,
  inner capillary break (e.g., roofing felt, self-adhering
  bituthene membrane), flashing and drainage
  elements of the roof systems;  identify the sequence
  of inspections  and tests,  the parties responsible
  for them and the required documentation of the
  results.
• Provide a list of inspection and maintenance
  requirements for the roofing, coping and flashing.
• Reference published roof assemblies designed
  to manage water vapor and condensation within
  the appropriate climate.  Perform  hygrothermal
  modeling when documentation through previous
  testing or modeling of a roof assembly in a
  particular climate or for unusual space humidity
  levels is not  available.
• Write a description detailing how the roof system
  manages water vapor during cooling and heating
  modes, as applicable. Drawings and specifications
  must identify vapor migration  control details
  and the permeability and insulating  values of all
  materials.
• Use the  pen  test (See Appendix A) to verify the
  continuity of the insulation layers and air barriers
  from the center of the roof to the intersection with
  the walls.

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Provide two-dimensional sections where two
materials that form the insulation layers and  air
barrier come together and three-dimensional
drawings where three or more elements of the
insulation and air barrier come together.
Specify a fan pressurization test in design
specification documents to assess the entire
building enclosure in accordance with ASTM
E779-10 Standard Test Method for Determining Air
Leakage Rate by Fan Pressurization, ASTM E1827-
96(2007) Standard Test Methods for Determining
Airtightness of Buildings Using an Orifice Blower
Door of the U.S. Army Corps of  Engineers Air
Leakage Test Protocol for Building Envelopes.
• Specify the target  airtightness level.
• Specify when the test should be conducted in
  relation to the completeness of the air barrier
  system.
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• Identify the appropriate testing party.
• Specify how the results should be documented,
  judged and accepted or rejected.
• Specify the remedies if the building fails the test.
Specify quality assurance programs for the
installation of the hygrothermal control elements of
the enclosure. Provide a list of critical details and
a schedule for inspecting the air barrier,  insulation
and vapor control elements of the roof assembly.
Specify the sequence of inspections,  the parties
responsible for the inspections, and the required
documentation of the inspection results.
Provide a list of inspection and maintenance
requirements for the interior finishes  if they are
critical to water vapor control.


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www.epa.gov/iaq/moisture
  Plumbing Systems
Issue
Moisture problems associated with plumbing
equipment include:
• Leaks in pressurized pipes and vessels, in
  appliances that use water and in pipes that drain
  wastewater.
• Condensation on cold-water lines,  chilled water
  lines and toilets. The colder these surfaces are, the
  more likely condensation will form.
• Mold growth on partitions, ceilings and floors
  enclosing spaces that are subject to repeated
  wetting.

Once installed, plumbing is difficult and expensive to
replace and relocate, so good design is very important.
Moisture problems associated with poorly designed
plumbing can cause damage that can affect almost
any location in the building,  including places that are
not often seen or inspected or are difficult to access.
Unnoticed mold growth can result from leaks, posing
a health risk to building occupants. Gaining access to
poorly designed plumbing for repair or replacement
can necessitate demolishing obstructions, which leads
to higher repair  costs.

Goals

Plumbing System Design  Goal 1: Design supply lines,
drain lines, and fixtures to prevent water leaks and
facilitate leak detection and repair.

Plumbing System Design  Goal 2: Design plumbing
systems to prevent condensation on cold water lines
and fixtures.

Plumbing System Design  Goal 3: Select materials to
minimize mold growth in  areas that are unavoidably
wet.

Guidance

Plumbing System Design  Goal 1: Design supply lines,
drain lines and fixtures to prevent water leaks and to
facilitate leak detection and repair.
Guidance 1: Reduce initial leaks by specifying testing
of supply lines, drain lines and fixtures.

Determine specifications for pressure tests of supply
and drain lines and fixtures to identify leaks in
plumbing.
• Design specifications should require, at a minimum,
  the testing of supply lines in accordance with
  section 312.5 of the International Plumbing Code,
  or relevant sections  of other applicable local codes,
  but they may require testing at higher pressures
  depending on the requirements of the equipment
  and plumbing system and the intent of the design.
• Design specifications should require, at a minimum,
  testing the drain and vent side of the plumbing
  system as required by the relevant building code.
  For example, designs should specify a gravity test
  of the drain  and vent side of the system according
  to sections 312.2, 312.3, and 312.4 of the
  International Plumbing Code, or relevant sections
  of applicable local codes. If all or a portion of the
  drain side of the system will  be pressurized during
  operation, appropriate pressure testing must be
  specified.
• Identify the  test method and the design test
  pressure.
• Specify when the tests should be conducted in
  relation to the completeness of the plumbing
  system and the closing of the cavities (e.g.,
  while lines are exposed for inspection,  but before
  enclosing).
• Identify the  appropriate testing party. Depending
  on the scale of the project and the parties
  involved, the appropriate testing party may be
  a commissioning agent; a testing, adjusting,
  balancing (TAB) contractor;  a subcontractor to the
  general contractor; or a plumbing contractor.
• Specify how the results should be documented,
  judged and accepted or rejected.
• Specify the remedies if any  portion of the plumbing
  system fails  the test.

Guidance 2: Design the plumbing system for easy
inspection and repair of components (e.g.,  pipes,
                                                   54

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valves, traps, grease traps, tanks, controls, heaters,
filters and connections to appliances).

Place pipes and valves where they can be easily
inspected and repaired, where  leaks will be seen
quickly, and where even a small leak will not wet a
cavity made from  moisture-sensitive materials. Avoid
locating water lines and other plumbing components
in exterior wall or  ceiling cavities insulated with
porous insulation. NOTE: If pipes must be located
in an exterior wall or ceiling, they must be protected
so that outdoor temperatures do not affect them and
outdoor air cannot leak in to them.  In addition to
any required pipe insulation, place  a layer of closed-
cell board or spray-foam insulation  between the pipe
and the exterior sheathing or curtain wall.  If board
foam is used, it must be air sealed  at the joints and
edges and connected in an airtight  way to the air
barrier system at all perimeter  edges. The object  is
to surround the pipe with warm interior air when  it is
cold outdoors and with cool, dry, conditioned air  in air
conditioning mode.

Plumbing System Design Goal  2: Design plumbing
systems to prevent condensation on cold water lines
and fixtures.

Guidance 1: Design the plumbing system's insulation
and water vapor controls so the pipes,  tanks and
other equipment that convey or contain water cooler
than the dew point of the outdoor air—or cooler than
the  expected dew point of the air in the enclosure
where the equipment will be located—are free of
condensation.
• Specify the design temperature and  humidity
  conditions for the spaces that contain plumbing
  components conveying cool or cold water (e.g.,
  chilled water lines, cold water lines, toilets, cold
  water storage tanks or water  treatment tanks) and
  the expected surface temperatures of these items
  during the design condition.
• Specify the required R-value of the insulation and
  the permeability and location of the water vapor
  control element to prevent condensation on the
  surface of the insulation or on the surface of the
  pipe or plumbing component.
• Specify air-sealing methods and materials at joints
  and seams in the insulation and water vapor control
  elements.
• Provide details showing the continuity of the
  insulation and water vapor control where pipes pass
  through walls, ceilings or floors and where  pipes
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  join other plumbing components such as valves,
  gauges, pumps and tanks.
• Require the inspection of condensation controls
  for components that convey cool or cold water and
  specify when in the construction sequence the
  inspections must take place, the party responsible
  for performing the  inspections, the methods that
  should be used to document the results of the
  inspections and any remedies for failed inspections.

Plumbing System Design Goal 3: Select materials to
minimize mold growth in areas that are unavoidably
wet.

Guidance 1: In unavoidably wet areas, use materials
that tolerate repeated wetting and drying.
• Identify areas in the building that will get wet
  because of their use (e.g., entryway floors,
  bathroom floors, tub surrounds, showers, locker
  rooms, pool and spa rooms, and  kitchens). Specify
  materials that are highly resistant to the growth
  of mold. Among these materials are ceramic tile,
  glass, plastic resins, metals and  cement-based
  products.
• For materials known to be vulnerable to mold
  growth (e.g., untreated paper-faced gypsum
  board and OSB), use products and paints that are
  resistant to mold growth.  Specify mold-resistance
  testing criteria that are appropriate for these
  materials (e.g.,  a score of  10 when tested using
  ASTM  D3273 Standard Test Method for Resistance
  to Growth of Mold on the Surface of Interior
  Coatings in an Environmental Chamber).
• Avoid specifying materials that provide nutrients
  and sustain mold growth. Such materials  include
  untreated paper-based products and composite
  wood materials.

Verification of Plumbing Design

Piping, Valves, and Controls
• Confirm that drawings and specifications document
  the location of pipes, valves and other plumbing
  system components and the  location, size and type
  of access  panels for inspection and repair.
• Confirm that the pressure test requirements of
  supply and drain lines, the specific responses
  to success or failure, the testing schedule,
  the responsible testing party and the required
  documentation  have all been specified.
• Provide a  list of critical details and a schedule  for
  inspecting the plumbing system  including supply


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  lines, drain lines, air vents, plumbing fixtures,
  appliances that use water, tanks and vessels.
  Specify the inspection sequence, the parties
  responsible for the inspections and the required
  documentation of the inspection results.

Insulation and Vapor Retarders
• Confirm that drawings and specifications include
  the design conditions, condensation control
  elements, inspection procedures, responsible
  parties and documentation as required.
• Provide a list of critical details and a schedule for
  inspecting the plumbing system insulation and
  vapor retarders, including supply lines and drain
  lines. Specify the inspection sequence, the parties
  responsible for the inspections and the required
  documentation of the inspection results.
Wet Spaces
• Confirm that the drawings and specifications
  identify appropriate moisture-resistant materials for
  use in wet locations including bathrooms, showers,
  locker rooms, pool and spa rooms, and  kitchens.
• Provide a list of inspection and maintenance
  requirements for the moisture-resistant materials
  used in the unavoidably wet areas.
• Provide a list of critical details and a schedule for
  inspecting the moisture-resistant materials  and
  associated liquid-water-control elements specified
  for use in unavoidably wet areas.  Specify the
  inspection sequence, the parties responsible for the
  inspections and the required documentation of the
  inspection results.
• Provide a list of inspection and maintenance
  requirements for the moisture-resistant materials
  used in the unavoidably wet areas.
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  HVAC Systems
                                                                                 www.epa.gov/iaq/moisture
Issues
Some of the moisture problems in buildings can
be caused or accelerated—or reduced or avoided
altogether—through the design and installation of the
HVAC system. The HVAC components that dehumidify
the ventilation air deserve careful attention because
outdoor air constitutes most of the annual humidity
load for nearly all buildings.

Common  HVAC-related contributors to moisture
problems include:
• Inadequate dehumidification by the HVAC system
  during  humid weather. The resulting high indoor
  air dew point can  lead to condensation,  near-
  condensation and mold growth. Comfort problems
  also are common when the indoor dew point is
  high because the relative humidity is also high.
  Occupants often demand lower thermostat settings
  in an attempt to be more comfortable. This is
  counterproductive. Lowering the thermostat
  overcools the building, which increases the risks
  of condensation,  excess moisture absorption and
  subsequent mold growth. Cold temperatures also
  further reduce comfort and increase energy costs.
• Leaking return and exhaust air duct connections,
  leaking indoor air  handler compartments operating
  under suction, and leaking return air plenums.
  These leaks create suction in building cavities,
  pulling humid outdoor air into the building where
  it can condense moisture onto cool surfaces and
  support mold growth.
• Leaking supply air duct connections and leaking
  indoor air  handler compartments  operating under
  positive pressure.  When the weather  is  hot or
  humid, these cold air leaks chill surfaces behind
  walls and above ceilings, creating condensation and
  supporting mold growth. During cold weather these
  same leaks can force warm, humid indoor air into
  cold cavities where it can condense and support
  mold growth and corrode structural fasteners.
• Oversized  cooling systems. When cooling
  systems, rather than dedicated dehumidification
  components, are expected to control  humidity, the
  traditional inclination of designers is to increase
  the cooling tonnage to remove the combined
  sensible and latent loads. But overpowered cooling
  systems have exactly the opposite effect. A large
  cooling system removes the normal sensible load
  very quickly. Then, to avoid over-chilling the space,
  compressors are shut off or chilled water flow rate
  is reduced before the coils can condense enough
  moisture to control humidity. In nearly all cases,
  oversized cooling systems do not solve humidity
  control problems—instead, they cause them.
• Ineffective drainage of condensate collected inside
  the HVAC system or condensation on the outside
  of the system's cold and uninsulated surfaces.
  Undrained and uncollected condensate leads to
  water leaks, drips  and subsequent moisture damage
  and mold risk.
• Failure to exhaust indoor humidity sources such
  as showers, bathrooms, spas, pools and kitchens,
  especially in residential buildings and sports
  facilities. Humid air can migrate from these sources
  to cold surfaces, leading to condensation or near-
  condensation and  subsequent mold growth and
  structural deterioration.




HVAC System Design Goal 1: Keep the indoor air dew
point  low enough to  reduce the risk of condensation
on cool surfaces and the risk of moisture absorption
by organic materials.

HVAC System Design Goal 2: Seal all duct
connections to prevent hot, humid outdoor  air from
being pulled into the building by leaking return  air
duct connections, leaking return air plenums and
unbalanced exhaust.  Sealed connections also prevent
condensation  caused by supply air escaping through
duct connections into unconditioned spaces.

HVAC System Design Goal 3: Prevent condensate
from cooling coils from overflowing into drain pans
and prevent condensation on the external surface
of cold pipes, valves, ducts, diffusers and indoor air
handler cabinets.
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HVAC System Design Goal 4: Limit indoor humidity
loads through effective exhaust ventilation—via duct
work with sealed connections—from showers, tubs,
kitchens, pools, spas and other significant sources of
moisture. Balance the exhaust air with dry makeup
air to prevent the exhaust from pulling unconditioned
outdoor air through the building enclosure.

Guidance

Building owners  and  HVAC designers will note that
this guidance is a necessarily brief summary of
several complex tasks. More detailed design methods
to achieve these  goals are presented in the ASHRAE
Humidity Control Design Guide for Commercial and
Institutional Buildings.

HVAC System Design Goal 1: Keep the indoor air
dew  point low enough to reduce the  risks from
condensation on  cool surfaces and from moisture
absorption  by organic materials.

Guidance 1: For  an air-conditioned building, design
the HVAC systems to include dehumidification
components and  a control system that will keep the
indoor air below a 55°F dew  point during humid
weather.

Indoor air held below a 55°F dew point cannot
condense moisture onto cool ducts carrying
supply air at 55°F.  Nor will moisture condense on
surfaces chilled by that supply air as it leaves the
supply air diffusers. And only very small amounts
of condensation,  if any, will form on  incompletely
insulated chilled-water piping. A maximum 55°F
dew  point control level provides an appropriate safety
margin to reduce the impact of minor shortcomings in
the building enclosure design and construction, and it
minimizes the risk of condensation from the inevitable
minor air leakage through duct connections.

Among the effective dehumidification techniques are:
• Drying all the ventilation air in a separate,
  dedicated outdoor air system (DOAS) to a dew point
  low enough to  remove the internally generated
  humidity loads. DOAS can also be designed to
  have other significant risk-reduction benefits. They
  can reduce ventilation air in response to reduced
  occupancy, which greatly lowers annual humidity
  loads, energy use and the risks associated with
  moisture accumulation. During occupied hours,
  dedicated outdoor air units can be used to provide
  a slight excess of dry ventilation air, so most of the
  air leaks  in the building enclosure involve dry air
  moving outward, rather than humid air moving into
  the building.  By providing a return air connection
  with a damper, the system can keep the building
  dry during unoccupied periods by recirculation,
  without the need to either ventilate or to operate
  the central cooling system.
• Arranging the main cooling system so it can
  sufficiently dry ventilation and return air to remove
  all of the humidity loads even when thermostats
  are not calling for cooling. This drying can be
  accomplished by using a separate dehumidification
  coil, or by a variable air volume cooling system. In
  both cases, the cooling coil must stay constantly
  cold and  not re-set to a higher temperature during
  periods of low sensible heat load. In a variable
  volume system, keeping the coil constantly cold
  will require reheating the supply air to some
  zones. To comply with energy codes and ASHRAE
  Standard 90.1, reheat energy should come from
  heat otherwise wasted, such as rejected heat from
  refrigeration condensers or heat from exhaust air.
  Also note that to avoid losing dehumidification
  capacity,  reheat  coils should be located well
  downstream  from dehumidification coils. Otherwise,
  the energy radiating from a closely coupled reheat
  coil will re-evaporate some of the condensed water
  as it drips from the dehumidification coil.
• Drying a portion  of the blended return and
  ventilation air with a secondary cooling coil or a
  desiccant dehumidifier that operates in response
  to a rise in the indoor dew point.  In this alternate
  arrangement, the air will follow a dual path: part of
  it will be  dried by the secondary coil or desiccant
  dehumidifier and the rest will bypass the main
  cooling coils unless there is a need for cooling.
  Reheat or post-cooling usually is  not required for
  this arrangement. After the dry air blends back  into
  the supply, the blended mixture is generally warm
  or cool enough for occupant comfort.

Guidance 2: Use the peak outdoor dew point design
conditions—not the peak sensible heat design
values—to estimate humidity loads when sizing
dehumidification components and systems.

• The largest sources of humidity load are  nearly
  always the ventilation air, the exhaust makeup air
  and air infiltrating through the building enclosure.
  These loads are at their peak when the outdoor
  air is at a moderate temperature but a very high
  humidity. At this peak outdoor dew point design
  condition, the humidity loads are 30 percent to
  100 percent greater than the humidity loads at the
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  hottest outdoor dry bulb conditions. So for sizing
  dehumidification loads and determining component
  performance, it is very important to use the
  ASHRAE peak dew point design conditions and not
  the peak cooling design conditions.
  Peak dew points along with their corresponding
  humidity ratio values for major North American
  and international locations are available in the
  ASHRAE Humidity Control Design Guide.  Those
  data and values for many additional locations
  also now appear in Chapter 14 of both the print
  and electronic editions of the ASHRAE Handbook
  2009—Fundamentals, as shown in Figure 2-17.
                             www.epa.gov/iaq/moisture
Guidance 3: Limit the operation of any air-side
economizer to only when the outdoor air dew point is
below 55°F.
• Air-side economizers have been responsible
  for significant problems related to moisture in
  buildings, especially schools and libraries that
  require only moderate cooling during lengthy
  unoccupied periods—a task well suited to cooling
  with outdoor air.  However, unless that outdoor air is
  dry as well as cool, the flood of air brought in during
  the economizer cycle adds a tremendous amount
  of moisture to the building and its contents.
  Controlling the economizer with an enthalpy control
  does not solve the problem because the outdoor
Figure 2-17 Peak Dew Point Data are Available in the Climatic Design Information Chapter of the ASHRAE Handbook—
Fundamentals
                                                                   Dehumidification
                                                                   Design Data
                                                                   Peak Dew  Point
                                                                            ***-"*
                                                                             A3
                                                                   Peak Dry Bulb
NOTE: The print edition of the ASHRAE Fundamentals volume for 2005 did not contain these values, but they are available on the
accompanying compact disk. The printed edition of the 2001 Fundamentals contains peak dew point values for a more limited set of
locations, as does the 1997 edition. Be aware, however, that the ASHRAE Fundamentals volumes from 1993 and earlier do not contain
values for peak dew point—only for the sensible cooling design extremes, which have much lower absolute humidity levels than the peak
dew point conditions.
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  humidity can still be too high even when its
  enthalpy is lower than indoors.
• An air-side economizer is still a useful energy-saving
  feature in less-humid climates. But the decision
  to bring in outdoor air for cooling should be made
  based on the outdoor air dew point as well as the
  outdoor dry bulb temperature. A maximum 55°F dew
  point is a good rule of thumb. If the outdoor dew
  point is above 55°F, do not bring in extra outdoor
  air for cooling, even  if its dry bulb temperature or its
  enthalpy is below the indoor value.

Guidance 4: Design the system to keep the indoor
dew point near or below 35°F when the outdoor
temperature falls below freezing.
• To limit the risk of damage from moisture and mold,
  the basic requirement for humidity control in the
  winter  is to avoid condensation inside the cold
  exterior wall. The  most appropriate maximum indoor
  dew point in the winter depends on the annual
  duration and severity of cold weather at the site,
  and on the design and construction of the building
  enclosure and its glazing.
• Higher indoor dew points provide more comfort
  during the winter, but  lower dew points are better
  for avoiding  condensation on cold surfaces on and
  inside exterior walls. A 35°F dew point maximum
  during winter weather  is a prudent compromise
  between these two competing goals for most
  commercial  and institutional buildings. That  level  is
  at the lower  boundary of the winter thermal comfort
  zone as traditionally defined by ASHRAE Standard
  55. And as noted in the ASHRAE  Humidity Control
  Design Guide, a 35°F dew point is still high enough
  to help limit uncomfortable electrostatic discharges
  and eye irritation for the general population.
• Museums, swimming pool enclosures and hospitals
  are  exceptions; they all have much higher winter
  indoor dew points for important reasons. Their
  building enclosures demand very careful attention
  to interior-side air tightness and vapor retarders on
  the inside surface of the exterior walls in order to
  limit their high risk  of  moisture problems due to
  wintertime condensation.
• For any type of building in an extremely cold
  climate; the more hours below freezing, the
  more important it will be to carefully analyze the
  condensation potential of the exterior wall and
  glazing designs and to install continuous air and
  vapor barriers inboard  of the buildings' insulation.
  Better  insulated and more air-tight building
  enclosures can tolerate higher indoor dew points to
  improve comfort for occupants.
• Most buildings are not mechanically humidified
  during the winter, but in some cases such
  humidification is useful and necessary. When
  the building is humidified, the designer should
  remember the advice of humidifier manufacturers,
  which is repeated in the ASHRAE Humidity Control
  Design Guide. Namely, consider splitting the
  required humidification capacity between several
  units in stages,  rather than install one single,
  large unit. Humidifier manufacturers warn that
  building moisture problems are sometimes caused
  by humidifiers that are so large they cannot be
  controlled at the lower end of their capacity. These
  units can overload the supply air with water vapor,
  causing condensation, moisture accumulation and
  water leaks from ducts.

HVAC System Design Goal 2: Prevent hot, humid
outdoor air from being pulled into  the building by
leaking return air duct connections, leaking return
air plenums and unbalanced exhaust. Prevent
condensation caused by supply air escaping through
duct connections.

Guidance 1: Specify that all duct connections on the
supply and return  air sides be sealed with mastic to
the standards established by SMACNA's HVAC Duct
Systems Inspection Guide for high-pressure duct work
(Seal Class A).
• Ducts and their connections need not be built
  to resist high pressures if they are not operating
  under high pressure.  However, all duct connections,
  especially where ducts meet air  handlers, must be
  sealed tight with mastic. NOTE: Recent energy code
  changes in several states have made this guidance
  a requirement. The requirement is based on the
  considerable energy cost savings and equipment
  size reductions  made possible by preventing air
  leaks into and out of  duct work.

Guidance 2: Specify that all joints and penetrations
of all return air  plenums be sealed with fire or smoke
sealant so that the plenum is open to air flow only
from the inside of the occupied space it serves—and
especially not open to inward leakage from exterior
walls, crawl spaces or basements.
• One classic problem area is an exterior wall where
  the gypsum wallboard does not extend all the way
  up to seal  against the bottom of the floor or roof
  above. Such openings to the inside of the exterior
  wall must  be  plugged with backing material such
  as glass fiber insulation and then sealed with
  liquid-applied conformal film such as fire or smoke
  sealant.
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• In commercial buildings, roof-mounted air
  conditioning units are often mounted on curbs
  above return air plenums. The joint between the
  curb and the unit must be sealed tight because it is
  effectively part of the duct system.
• Fire codes sometimes allow vertical plumbing
  chases to be used as return air ducts,  a situation
  that can  be found in low-cost construction. The
  volume of air that leaks  into such chases is likely
  to be extreme, however,  and likely to come from
  undesirable  locations such as basements and
  crawl spaces, loading the return air with humidity,
  particulates  and microbiological contaminants. To
  avoid problems, the designer should insist that all
  spaces used as air ducts be sealed and tested for
  air tightness.
• In low-rise school, office and retail strip mall
  construction, the joint between the exterior walls
  and roof  often includes an open soffit  under the
  eaves. A  return air plenum that can draw air
  through that soffit becomes, by accident, an ail-
  outside air system. Any building that has a soffit
  requires special attention from the HVAC designer
  to ensure that return air is pulled  from the occupied
  space and not from  outdoors.

Guidance 3: Design the systems to manage indoor-
outdoor air  pressure relationships. If a building
enclosure has been designed and constructed with
an effective air barrier, continuous insulation layers,
and rainwater control as required by this guide,
then for ordinary occupancies enclosure-related
problems are not very  sensitive to indoor-outdoor
pressure relationships. In warm, humid climates (See
Climate Zone map,  Figure  2-5) maintaining a slight
positive pressure during cooling conditions adds
extra protection against condensation in  the building
enclosure.

To create a  slight positive pressure,  add  up all the
exhaust air  volumes from all zones served by a single
system. Design the air conditioning  system for those
zones so that the total of the dry makeup/ventilation
air exceeds the total exhaust from those  areas by 5 to
10 percent. Balance the exhaust and ventilation air
flows during humid weather so that the building stays,
on average, under slightly  positive air pressure (5 Pa
or 0.02" WC). Use dry ventilation air to accomplish
this slight positive  pressure.

Maintaining an average positive air pressure can also
be accomplished more explicitly and automatically
by sensing  the pressure difference between indoors
                             www.epa.gov/iaq/moisture
and outdoors and using that signal to control a relief
damper on small buildings and one or more relief
air fans on larger buildings. Such a pressure control
system makes it easier for the building operations
staff to reverse the direction of the pressure difference
for winter operation.
• When outdoor air temperatures are below freezing
  and indoor relative humidity must be maintained
  above 35 percent, there are advantages to operating
  under neutral or slightly negative air pressure so
  humid indoor air is not forced  into cold exterior wall
  cavities, where it could condense moisture.
• Note that some buildings such as hospitals,
  museums, and high-rise buildings,  as well as areas
  such as walk-in freezers and indoor swimming
  pools, require special care with respect to air
  balance. Their unique and sometimes critical needs
  for specific pressure  differences between spaces
  necessitates consultation with  industry-specific
  references for more detailed and appropriate
  guidance.

HVAC System  Design Goal 3: Prevent normal
condensate from cooling coils from overflowing drain
pans and  prevent condensation on the outside of cold
pipes, valves, ducts, diffusers and indoor air handler
cabinets,  as recommended  by ASHRAE Standard
62.1-2007.

Guidance 1: Specify that all cooling coils be
equipped  with condensate drain  pans that have these
characteristics:
• The pan is  long enough in the  direction of air flow
  to catch any condensate blown off the coil during
  heavy condensing conditions.
• The pan drains from  its lowest point and slopes
  towards that lowest point from two directions to
  ensure there is never any standing water in the pan.
• Any drain pan that does not have a condensate
  pump is equipped with a trap on the condensate
  drain  line deep enough to ensure no water remains
  in the pan drain  when the fan  is operating.
• The trap is vented on the outlet side to ensure that
  plug flow in the downstream condensate piping
  does not siphon water out of the bottom of the trap.
• The condensate drain line and trap are accessible
  and detachable to allow cleanout with a  brush.
• Clearances around the duct work and duct access
  doors allow for regular inspections and cleaning of
  the condensate drain pan.
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Guidance 2: Specify that all interior faces of duct
work or plenums located immediately downstream
from cooling coils be lined with smooth, washable,
water-impermeable material to prevent accumulation
of moisture and dirt on those surfaces. It is a prudent
rule of thumb to have an impermeable and washable
surface for at least the first 10 feet downstream of
dehumidification coils. Also specify that:
• Any joints in the moisture-impermeable lining are
  sealed watertight.
• The outlet duct work or plenum is equipped with
  a gasketed door large enough to ensure access
  adequate for inspecting and cleaning downstream
  duct surfaces.

Guidance 3: Design the component layout so that
filters are located either upstream of cooling coils or
far enough downstream so they do not collect droplets
of moisture stripped from the coil during periods of
heavy condensation. For coils  intended principally as
dehumidification components, specify:
• Coil fin height no greater than 4 feet above the
  bottom of the drain pan, face velocity below 400
  feet per minute, and spacing of eight fins per inch
  or wider to minimize water accumulation on the fins
  and subsequent droplet carryover into the supply air
  under heavy condensing conditions.
• Maintenance access upstream  of the coil through
  one or more gasketed doors that are sufficiently
  large to allow the full width  and height of the coil
  surface to be cleaned.

HVAC System Design Goal 4: Limit indoor humidity
loads through effective exhaust ventilation—through
duct work with sealed connections—from showers,
tubs, kitchens, pools, spas and any similar significant
sources of indoor humidity.

Guidance 1: Provide exhaust ventilation of strong
humidity sources (e.g., showers and bathtubs,
spas, cooking ranges, commercial dishwashers and
combustion devices), as recommended by ASHRAE
62.1-2007 and ASHRAE 62.2-2004.  In addition:

• Specify sealing of all exhaust air duct work
  connections to SMACNA seal class  A using mastic.
  Pay special attention to the joint where the ducts
  connect to the exhaust grille collars and to the
  inlets and outlets of fan compartments. This sealing
  is important for all exhaust ducts in all buildings,
  but it is especially important for ducts that have
  continuously operating exhaust fans, such as those
  in the bathrooms of hotels and eldercare buildings.
  Many of these buildings have suffered frequent
  mold  problems as a direct result of leaking exhaust
  duct connections. Such leaks create suction that
  pulls  humid air into the building, where its moisture
  condenses or is absorbed into cool wall board and
  onto ceiling tile and furnishings where the moisture
  supports mold growth.
• For exhaust ducts from commercial kitchens,
  spas,  pools, athletic building showers and other
  hot, high-humidity spaces, require duct insulation
  in order to avoid internal condensation. Specify
  similar insulation for exhaust ducts from residential
  bathrooms and kitchens in cold climates, because
  the dew point in the exhaust air is likely to be above
  the cool indoor air temperatures in the unheated
  cavities and attics that the ducts  pass through on
  their way to the outdoors.
• Design exhaust ducts to terminate outdoors and
  not in unconditioned indoor areas such as attics or
  crawl  spaces.
• Do not terminate the exhaust duct by directing
  exhaust air through the ventilated soffit under
  eaves. The  hot and humid air will quickly rise and
  re-enter the attic space through nearby vents in the
  same soffit,  leading to mold growth in the attic and
  on the roof's  inside surface.


Verification of HVAC System Design

Cooling Season Dew Point Control

• Explain in the design specifications the operation
  of the air conditioning and dehumidification
  equipment at design dew point conditions and the
  expected humidity removal under those conditions,
  expressed in  pounds of water vapor removed per
  hour.
• Require that the supplier of the dehumidification
  component or system provide written
  documentation of the equipment's performance—
  including pounds of water vapor removed per
  hour,  total air flow, and the temperature of air as
  it leaves the device—when the system is operating
  under peak outdoor dew point conditions. These
  conditions will always be of reduced sensible heat
  loads, so the suppliers' submittals for the peak dew
  point  conditions will provide very useful snapshots
  of the behavior of the entire system's operation
  under part-sensible-load conditions—temperature
  conditions that occur for thousands, rather than
  dozens, of hours every year.

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• Require that the dehumidification system be
  tested, adjusted and balanced and that reports
  from that process verify and document the system's
  performance after the system is running. At a
  minimum, measure and document the design
  versus actual air flow through the device and the
  temperature and humidity ratios of the air as it
  enters and exits the device, then calculate the
  equipment's performance in pounds of water vapor
  removed per hour.
• Require that the economizer air-flow and damper
  operation be tested, adjusted and balanced and
  require reports from that process that  will verify
  and document the economizer air flow rate. The
  Test, Adjust and Balance  (TAB) report should also
  confirm that the economizer damper has been  seen
  to open correctly and that the dampers and control
  set points allow the economizer to operate only
  when the outdoor air dew point is below 55°F.

Winter Condensation Control

• Design the installation surrounding any humidifier
  in strict accordance with the manufacturer's
  recommendations for exterior insulation and for
  unobstructed lengths of straight duct downstream
  for complete vapor absorption. Also ensure that
  the controls allow smooth modulation  of humidity
  production down to 20 percent of the  equipment's
  peak design capacity.
• Require that any humidifier and its control system
  be tested, adjusted and balanced and that the
  ductwork downstream be  checked for condensation
  during operation of the humidifier.  Require reports
  that measure and verify total air flow and the
  temperatures and  humidity ratios of entering and
  leaving air.
Air Distribution
• Minimal requirement: Require the general
  contractor to inspect all sides of all joints between
  ducts and air handlers and to provide a written
  report that all sides of joints to and from  air
  handlers are sealed with mastic. Also require the
  installer to certify that all other joints in the system
  have been sealed with mastic.
• Robust requirement: Require that the completed
  system, including air handlers, be tested  for
  air tightness in accordance with SMACNA
  requirements for commercial  buildings or with the
  Air Conditioning Contractors Association  (ACCA)
  recommendations for residential buildings.  Require
  a written report of measured air leakage values  in
  accordance with the recommendations  of those
  organizations.
• Require the HVAC contractor to inspect all sides
  of return air plenums and provide a written  report,
  including photographs, that documents all joints
  and penetrations are effectively sealed.
• Require that the written TAB report provide
  assurance that all exhaust duct joints, and
  especially their connections to exhaust grilles and
  exhaust fans, have been inspected to confirm they
  have been sealed with mastic.
• Require that the air conditioning and exhaust
  systems be tested, adjusted and balanced.
• Include in the TAB process a  pressure map of the
  building during air conditioning and  heating modes
  documenting indoor-outdoor pressure differences
  over the course of daily sequences.
• Require reports from the TAB process that will
  verify and document system air flows after the
  system  is running.
REFERENCES
Advanced Energy. Closed Crawl Spaces: A Quick Reference for the
    Southeast. 2003. Online. Internet. Available at: http://www.
    crawlspaces.org. Accessed Novembers, 2013.
    (This condensed document provides details and technical
    information for designing and constructing closed, insulated
    residential crawl spaces. The full research reports underlying
    the crawl space recommendations can also be downloaded
    from the site [www.crawlspaces.org]. Although the research
    was conducted in North Carolina, many of the results can be
    applied to other climates.)

Air Conditioning Contractors of America (ACCA) Residential Duct
    Systems - Manual D - ANSI/ACCA1-2002 ISBN 1-892765-
    00-4 ACCA, 2800 Shirlington  Rd, Suite 300, Arlington, VA
    22206. ACCA.org
    (This guidance for duct design and installation is the basis
    for building codes in several states, and it is an ANSI-
    approved national standard.)

Air Movement & Control Association, International, Inc. (AMCA).
    AMCA 500-L-99 - Laboratory Methods of Testing Louvers for
    Rating.

Air Tightness Testing and Measurement Association. Technical
    Standard 1. Measuring Air Permeability of Building
    Envelopes. 2006.

American Society for Testing and Materials (ASTM). ASTM 1554-
    03 - Standard test methods for determining external air
    leakage of air distribution systems by fan pressurization.
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American Society for Testing and Materials (ASTM). ASTM D
    3273 - Standard test method for resistance to growth of
    mold on the surface of interior coatings in an environmental
    chamber.

American Society for Testing and Materials (ASTM). ASTM £779-
    03 - Standard test method for determining air leakage rate by
    fan pressurization.

American Society for Testing and Materials (ASTM). ASTM
    WK4201 - New standard test method for resistance to mold
    growth on building products in an environmental chamber.

American Society for Testing and Materials (ASTM). ASTM
    WK8681 - New standard test method for resistance to
    mold growth on interior coated building products in an
    environmental chamber.

American Society of Heating,  Refrigerating and Air-Conditioning
    Engineers (ASHRAE). ASHRAE Handbook of Fundamentals.
    ASHRAE Standard 62.1 - 2004 Ventilation for Acceptable
    Indoor Air Quality, ASHRAE 2004.
    (The ASHRAE ventilation standard provides information
    needed to determine ventilation rates for differing
    occupancies plus a number of design and O&M requirements
    to ensure proper performance of ventilation  equipment.
    Section 6.2.8 applies specifically to exhaust ventilation.
    Standard 62.1 applies to many situations.)

American Society of Heating,  Refrigerating and Air- Conditioning
    Engineers (ASHRAE). ASHRAE Handbook of Fundamentals.
    ASHRAE 62.2 -2004 Ventilation and Acceptable Indoor Air
    Quality in Low-Rise Residential Buildings.
    (This standard applies to low-rise residential buildings.
    Exhaust systems are covered in portions  of sections 5, 6 and
    7.)

American Society of Heating,  Refrigerating and Air-Conditioning
    Engineers (ASHRAE). ASHRAE Handbook of Fundamentals.
    ASHRAE Standard 90.1-2004 and Addenda -  Energy
    Standard for Buildings Except Low-Rise  Residential
    Buildings.
    (This standard provides minimum requirements for the
    energy-efficient design of all buildings, with the exception of
    low-rise residential buildings.)

American Society of Heating,  Refrigerating and Air-Conditioning
    Engineers (ASHRAE). ASHRAE Handbook of Fundamentals.
    ASHRAE Standard 160 P - Design Criteria for  Moisture
    Control in Buildings.

Baker,  M.C. Drainage From Roofs. Canadian Builders Digest no.
    151. 1972.
    (This digest is a general discussion of roofs and roof drainage
    and highlights many roof drainage design considerations.)

Brennan, T, Cummings, J, Lstiburek, J. Unplanned Airflows and
    Moisture Problems. ASHRAE Journal. November 2002.
    (This article reviews  the moisture dynamics  caused by
    unplanned airflows during heating and cooling modes and
    discusses interventions that can be made to prevent or solve
    the problems.)

Building Science Corporation. Read This Before You Design,
    Build or Renovate. Revised May 2005. Available at
    http://www.buildingscience.com/documents/guides-and-
    manuals/gm-read-this-before-you-design-bui Id-renovate/
    view?searchterm=read+this. Accessed November 6,  2013.
    (This pamphlet offers guidance about remodeling practices
    that foster healthy homes by reducing occupants' risk of
    exposure to known hazards. These practices also frequently
    yield other benefits such as improved durability and reduced
    operating costs.)

Canada Mortgage and Housing Corporation (CMHC). Best Practice
    Guides.
    (Design guides with underlying building science discussions,
    well-thought-through details for climate zones 6 and 7.
    Guides are available for flashing,  brick veneer and steel
    studs, brick veneer and concrete masonry unit backing,
    external insulation and finish systems, glass and metal
    curtain walls, architectural precast concrete walls, and wood
    frame envelopes.)

Connecticut Department of Environmental Protection.  2004
    Connecticut Storm water Quality Manual.
    (This manual  provides guidance on the measures necessary to
    protect waters from the adverse impacts of post-construction
    storm water.  It applies to new development, redevelopment
    and upgrades to existing development. The manual focuses
    on site planning, source control,  pollution prevention and
    storm water treatment practices.)

Department of the Army. Site Planning and Design. TM 5-803-6.
    October 1994.
    (This technical manual describes the site planning and
    design process used to develop a project to fulfill facility
    requirements and create the optimal relationship with the
    natural site. The manual focuses on the site planning and
    design process as it leads from program and site analysis to
    the preparation of a concept site plan.)

Ferguson, Bruce K. 2005. Porous Pavements CRC Press/Taylor &
    Francis, crcpress.com ISBN  0-8493-2670-2
    (This 577-page  book provides comprehensive guidance and
    case histories for design, construction and maintenance
    based on 25 years of practical experience with porous
    pavements, their hydrology and their relationship to storm
    water drainage and surface water management for buildings,
    roads, parking lots and landscape vegetation.)

Gatley, Donald. Dehumidification Enhancements for 100-Percent-
    Outside-Air AHUs, Parts 1-3. September,  October and
    November 2000.
    (This three-part series of articles  describes the underlying
    psychrometrics in ventilating buildings and provides
    design guidance for several methods of enhancing the
    dehumidification performance of air conditioning and
    ventilation systems.)

Georgia Stormwater Management Manual Volume 2: Technical
    Manual First Edition. August 2001.
    (This volume provides guidance on the techniques and
    measures that can be implemented to meet a set of storm
    water management minimum standards for new development
    and redevelopment. It is designed to provide the site designer
    or engineer with information required to effectively address
    and control both water quality and quantity on a development
    site.)
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Harriman, Brundrett, and Kittler. Humidity Control Design
    Guide for Commercial and Institutional Buildings (ASHRAE
    Humidity Control Design Guide). American Society of
    Heating, Refrigerating, and Air-Conditioning Engineers. ISBN
    1-883413-98-2.
    (This manual by ASHRAE discusses the design of cooling
    equipment to include dehumidification performance. Design
    analysis includes peak outdoor air dew  point performance as
    well  as peak outdoor temperature analysis.)

Henderson, H., Shirey, D., Raustad, R. Understanding the
    Dehumidification Performance of Air Conditioning Equipment
    at Part-Load Conditions.  Presented at the CIBSE/ASHRAE
    Conference, Edinburgh, Scotland 1-24-26 September 2003.
    (This technical paper presents analysis and data on
    the degradation of dehumidification performance of air
    conditioning equipment during partial-load conditions.
    Controls and systems that contribute to this problem are
    discussed.)

HyglRC (A hygrothermal modeler from the Institute for Research
    in Construction in Canada [http://archive.nrc-cnrc.gc.ca/
    eng/projects/irc/hygirc.html]. Accessed  Novembers, 2013.
    HyglRC is a modeler that is actively supported by the IRC.
    LikeWUFI and MOIST, HyglRC assumes no air flow through
    the assembly.)

International Code Council (ICC). 2003 ICC International Building
    Code.
    (Chapter 18 provides code requirements for soils and
    foundations including requirements for excavation, grading
    and fill around foundations. Section 1203.3.1 contains
    requirements for ventilated crawl spaces.)

International Code Council. 2003 ICC International  Plumbing
    Code.
    (Chapter 11 provides code requirements for storm drainage,
    including roof drainage requirements. Sections 312.2 to
    312.5 specify a gravity test of the drain and vent side of
    plumbing systems.)

International Code Council (ICC). International  Energy
    Conservation Code (IECC).
    (The IECC addresses energy efficiency in homes and
    buildings.)

Kanare, H. Concrete Floors and Moisture, Portland Cement
    Association, Skokie, Illinois, cat. no. EB119, 156 pp., 2005.

Lstiburek, Joseph 2006. Understanding  Attic Ventilation.
    ASHRAE Journal 48: 36.
    (This ASHRAE Journal article covers the underlying principles
    of attic ventilation in buildings.)

Lstiburek, Joseph 2006. Understanding  Basements. ASHRAE
    Journal 48: 24
    (This article identifies moisture control  problems often
    observed in basements and solutions to such problems.)

Lstiburek, Joseph 2006. Understanding  Drain Planes. ASHRAE
    Journal 48: 30
    (This ASHRAE Journal article covers the underlying principles
    of rainwater control in buildings, focusing on the use of
    weather-resistant materials that provide shingled drainage
    beneath siding materials.)
                                  www.epa.gov/iaq/moisture

Lstiburek, Joseph. Understanding Retarders. ASHRAE Journal.
    August 2004.
    (This ASHRAE Journal article covers the underlying principles
    of vapor retarders in buildings.)

Lstiburek, Joseph 2004. Understanding Vapor Barriers. ASHRAE
    Journal 46:40
    (This ASHRAE article describes water vapor dynamics in
    wall  sections and provides a flow-chart  method of selecting
    materials for the inside and outside of cavity walls with
    appropriate water vapor permeability for specific climates.
    Assemblies can  be  designed without using computer
    simulation.)

MOIST (MOIST  is a hygrothermal modeling  program available
    as a  free download  from the National Institute of Science
    and Technology  [http://www.nist.gov/el/highperformance
    buildings/performance/moist.cfm]. Accessed November  6,
    2013. The  calculation kernel in MOIST is not as complex as
    HyglRC or WUFI, but it is significantly  better than simplified
    steady state dew point-temperature profile calculations.  It
    provides a thermal  network analysis, includes solar radiation
    gains (but not rainwater or plumbing leaks), capillary
    migration and partial-pressure-driven vapor migration. Like
    WUFI and HyglRC,  MOIST does not model airflow effects.)

National Asphalt Pavement Association. Online. Internet.
    Available at http://www.asphaltpavement.org/.
    (The National Asphalt Pavement Association is a trade
    association  that provides technical, educational, and
    marketing materials and  information to its members and that
    supplies technical information concerning paving materials.)

National  Institute of  Building Sciences (NIBS). Building Envelope
    Design Guide (Whole Building Design Guide). Online.
    Internet. Available at http://www.wbdg.org/design/envelope.
    php. Accessed November 6, 2013.
    (Under guidance from the Federal  Envelope Advisory
    Committee, the  NIBS developed this comprehensive guide
    for exterior  envelope design and construction for institutional/
    office buildings. Sample specifications  and sections are
    included.)

Odom, J.D.  and  DuBose, G.H. Mold and Moisture Prevention.
    National Council of Architectural Registration Boards.
    Washington, DC, 2005.
    (This manual  is  the 17th monograph in  NCARB's Professional
    Development Program. It contains substantial narrative
    describing moisture and  mold problems in buildings
    and specific design and construction considerations for
    enclosures  and HVAC systems as they relate to moisture and
    mold problems.)

Rose,  William. Water in Buildings: An Architect's Guide to
    Moisture and Mold. John Wiley &  Sons, 2005.  ISBN:
    0471468509
    (This is not a design guide, but rather a deeper look at water
    and its behavior in  regard to building materials, assemblies
    and whole buildings. Illustrated with specific examples,  it
    explains the how and why of moisture control.)
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Sheet Metal and Air Conditioning Contractors' National
    Association (SMACNA). SMACNA Air Duct Leakage Test
    Manual. 1985.
    (A companion to  HVAC Duct Construction Standards - Metal
    and Flexible, this manual contains duct construction leakage
    classification, expected leakage rates for sealed and unsealed
    ductwork, duct leakage test procedures, recommendations on
    the use of leakage testing, types of test apparatus and test
    set-up and sample leakage analysis.)

Sheet Metal and Air Conditioning Contractors' National
    Association (SMACNA). Architectural Sheet Metal Manual -
    Fifth Edition. 1993
    (The SMACNA Architectural Sheet Metal Manual provides
    design criteria and details for roof drainage systems, gravel-
    stop fascia, copings, flashing, building expansion, metal
    roof and wall systems, louvers and screens and other metal
    structures. Chapter 1 contains data, calculations and charts
    for designing roof drainage systems.)

Spray Polyurethane Foam Association. Spray Polyurethane Foam
    for Exterior Subgrade Thermal and Moisture Protection.
    (This publication is a technical guide to specifying closed-cell
    spray foam polyurethane on the outside of basement walls as
    thermal insulation and moisture  protection.)

Straube, John. 2011. High Performance Building Enclosures.
    Somerville, MA:  Building Science Press (This book includes
    the fundamentals underpinning the physics of heat, air and
    moisture control  in high-performance building enclosures and
    practical design guidance to achieve them for a wide array of
    enclosure assemblies in all North American climate zones.
    There is a section on condensation control in wall and roof
    assemblies.)

Texas Water Development Board. The Texas Manual on Rainwater
    Harvesting.
    (This manual presents an interesting discussion on the history
    of rainwater collection, harvesting system components, water
    quality and treatment, system sizing and best management
    practices.)

United States Environmental Protection Agency. Alternative
    Pavers (Post-Construction Stormwater Management in
    New Development and Redevelopment). Online. Internet.
    Updated May 2006. Available at http://cfpub.epa.gov/
    npdes/stormwater/menuofbmps/index.cfm?action=min
    measure&min measure id=5. Accessed November 6, 2013.

United States Environmental Protection Agency. Construction Site
    Stormwater Runoff Control. Online.  Internet. Updated May,
    2006. Available at http://cfpub.epa.gov/npdes/stormwater/
    menuofbmps/index.cfm?action=min measure&min  measure
    id=4. Accessed November 6, 2013.
    (This resource provides detailed  information on construction-
    phase storm  water management, including best management
    practices.)
United States Environmental Protection Agency. National Menu
    of Stormwater Best Management Practices. Online.  Internet.
    Updated May, 2006. Available at http://cfpub.epa.gov/npdes/
    stormwater/menuofbmps/index.cfm. Accessed November 6,
    2013.
    (This resource provides detailed information including
    applicability, design criteria, limitations and maintenance
    requirements on these and many other site drainage
    methods.)

United States Environmental Protection Agency. Porous
    Pavement (Post-Construction Stormwater Management in
    New Development and Redevelopment). Online. Internet.
    Updated May, 2006. Available at http://cfpub.epa.gov/
    npdes/stormwater/menuofbmps/index.cfm?action=min
    measure&min measure id=5. Accessed November 6, 2013.

United States Environmental Protection Agency. Post-
    Construction Stormwater Management in  New Development
    and Redevelopment. Online. Internet. Updated May,
    2006. Available at http://cfpub.epa.gov/npdes/stormwater/
    menuofbmps/index.cfm?action=min measure&min  measure
    id=5. Accessed November 6, 2013.
    (This resource provides detailed information on post-
    construction Stormwater management including O&M best
    management practices.)

United States Environmental Protection Agency. Source  Water
    Practices Bulletin: Managing Storm Water Runoff to Prevent
    Contamination of Drinking Water. EPA 816-F-01-020. July
    2001. Available at http://www.epa.gov/safewater/sourcewater/
    pubs/fs swpp stormwater.pdf. Accessed  November 6, 2013.
    (This fact sheet focuses on the management of runoff in
    urban environments.)

Water Management Committee of the Irrigation Association. Turf
    and Landscape Irrigation Best Management Practices.
    (The Irrigation Association is involved with public policy
    issues related to standards, conservation and water  use on
    the local, national and international levels.)

WUFI (Hygrothermal modeling software to assess the water vapor
    dynamics of wall and  roof systems in numerous climates.
    WUFI is one of the more complete treatments of water
    vapor dynamics in assemblies. WUFI is available from the
    Fraunhofer Institute of Building Physics rhttp://www.hoki.
    ibp.fraunhofer.de/1 in  Germany. A limited  version of  WUFI
    is available free from Oak Ridge National  Laboratory Fhttp://
    www.ornl.gov/sci/btc/apps/moisture/1.) Accessed November 6,
    2013.
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                                                                                 www.epa.gov/iaq/moisture
 Chapter  3:   Constructing to  Prevent  Moisture Problems
 Introduction

This chapter is for the people who turn design
documents into buildings.  More attention is being
paid to moisture control during construction now than
ever before because of  increased concern about mold
growth in buildings. In  this chapter moisture control
issues are divided into two major topics:
1.  Control of water during the  construction of the
    building.
2.  Effective implementation of the moisture control
    requirements specified by the designers in the
    construction documents and associated contracts.

Erecting a building often involves several companies
providing services from multiple trades. The general
contractor has the primary responsibility and
contractual obligation for the building's construction.
The physical work often is  carried out by specialized
subcontractors such as landscapers, roofers, glazers,
concrete and masonry contractors, steel fabricators,
electrical contractors, insulation and waterproofing
contractors and mechanical contractors. Providing
moisture control during construction is largely
the responsibility of the general contractor  and
the subcontractors.  However, firms specializing in
construction management  or building commissioning
may have responsibilities for moisture control.

The concept of commissioning  traditionally has been
applied to heating, ventilation,  and air conditioning
(HVAC) systems. Commissioning has been very
effective in reducing problems  and  increasing  energy
efficiency and comfort. Over the past decade, this
process has been extended to entire electrical
systems; potable water, sanitary, drainage and
irrigation systems; power production and cogeneration
systems; the building enclosure; sustainable aspects
of the project; and the entire building design process
(ASHRAE Guideline 0:  The Building Commissioning
Process, GSA The Building Commissioning Guide,
and the National Institute of Building Science [NIBS]
Total Building Commissioning Program).
If a commissioning agent is involved in the design
and construction of a building, many of the quality
assurance procedures for moisture control and
associated measures could easily fall within the
commissioning agent's scope.

During the initial meetings, the contractor can
develop a plan to:
• Protect the building from, and respond to, moisture
  problems during construction.
• Implement the moisture control elements,
  verification activities and commissioning activities
  detailed in the drawings and specifications.

Moisture control policies to protect the building
during construction and to ensure the design has been
effectively implemented  should be in place before
construction begins. After agreement on moisture
control issues has been reached, the contractor must
implement and verify the moisture controls required
during construction and those required for the
successful operation of the building.


Control of Moisture During Building Construction

Construction companies  have always had to deal with
moisture problems at the construction site. Materials
and equipment get wet from:
• Rain.
• Water used in materials that are installed wet.
• Leaks in temporarily or permanently  installed
  plumbing.
• Condensation in the building before  it is enclosed.
• Poor humidity control after the building is enclosed,
  but before the HVAC system is operational.

As the site work begins and before the  building
is enclosed,  contractors may use temporary site
drainage, pumps,  and dunnage and tarps to keep
the site and  materials relatively dry. Many of the
materials used in the early phases of a project will not
be damaged if they get wet, although some will have
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to be dried before they can be used. For example,
foundation materials need to be dry before some
coatings and flooring can be applied.

The sequence of activities plays an important role in
preventing moisture problems during construction
• Moisture-sensitive and moisture-absorbing material
  and equipment should be scheduled for delivery
  when dry, protected storage is available.
• Wet, porous materials should be dry before
  moisture-sensitive materials are installed or
  moisture-sensitive coatings are  applied.
• Moisture-sensitive materials need to be protected
  from the weather as they arrive  on site. Measures to
  keep rain away from the materials may also protect
  them from damage by dust and wind.
• It  is preferable to enclose the building so it
  is  weather-tight before the moisture-sensitive
  materials arrive. While this situation can be
  planned for smaller projects, it  may not be possible
  for larger ones. In these instances, contractors
  may provide temporary shelter for materials and
  equipment stored on site. They  may protect partially
  completed work with tarps, temporary enclosures,
  or  temporary  bulkheads at floor  penetrations.  For
  example, gypsum board, brick,  concrete block
  and wooden materials can be wrapped in plastic,
  covered by tarps or plastic and  stacked on pallets
  in  well-drained areas. Some materials that need to
  be protected, such as brick and concrete masonry
  units, can be delivered wrapped in plastic.
• The lower stories of high-rise buildings are often
  being finished while the upper floors are still open
  to  the weather. This situation requires using upper
  floors as temporary protection by making temporary
  bulkheads at floor penetrations  and draining floors
  to  the perimeter. Increasingly, contractors also use
  dehumidification equipment to  dry out buildings
  that are enclosed,  but not yet air conditioned.
• In  spite of the best efforts to keep material and
  equipment dry, accidents still happen and things
  do get wet. Brick and concrete  block may have
  absorbed water before they were delivered or while
  they were stored at the site. Heavy wooden timbers
  may have been milled and installed while still
  green. The earthen floor of a crawlspace foundation
  is  a large area of soil exposed to the weather right
  up until the overhead floor deck is  installed. Some
  materials get wet accidentally because of rain or
  for other reasons. It is important to  dry out any
  moisture-sensitive materials as  quickly as possible.
Implementing the moisture control features of the
design consists of two essential actions
1.  Understanding the moisture control design
    features in detail and ensuring their
    constructability.
2.  Ensuring the moisture control features are
    effectively installed.

Coordination between construction companies who
are obligated to control moisture in buildings as
specified in the construction documents and building
designers (architects and engineers) will enhance
moisture control in the building. The contractor
should review the moisture-control elements of
the enclosure and mechanical  system designs and
discuss them with the designer(s) at the start of
the project. However, contractors, subcontractors,
construction management personnel, commissioning
agents, and owners frequently  propose alternative
details, materials, or equipment. It is  important to
note that these changes can lead to changes in the
moisture control requirements  of the building and
must be included in moisture planning. This includes
proposals made during the bid process; during the
development and review of submittals; at initial
meetings between the contractor, designer, owner,
and construction management service; or during
meetings to review submittals, construction progress,
difficulties,  and responses to problems that have
arisen. The contractor is urged to read Chapter 2 of
this document to become familiar with the moisture
control guidance for designers. The construction
documents can be compared with the design
recommendations of Chapter 2.

Scheduling is an ever-changing target that requires
juggling the schedules of numerous suppliers, sub-
contractors, supervisors and inspectors. This already
daunting task can be further complicated by larger
issues, such as changes in markets or disasters in
other parts of the world, that might affect the price
and availability of supplies. It  is crucial that the
materials required to control moisture in the enclosure
and the equipment required to control humidity in
the building arrive so they can  be installed in the
correct sequence. For example, the drain plane or air
barrier within a wall must  be installed before the wall
is closed in; otherwise, proper  installation  becomes a
matter of demolition and reconstruction.
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Whether the general contractor is coordinating
the installation of moisture control systems or a
subcontractor is installing them, it is crucial to have
a quality assurance program in place to inspect, test
and document the correct installation and functioning
of the moisture control elements. This may mean
the difference between avoiding or having a moisture
problem. Some examples of moisture problems resulting
from poor or no quality assurance practices are:
• Missing flashing.
• Flashing installed with laps reversed.
• Flashing that stops short of becoming a through
  flashing.
• Missing insulation.
• Missing sealant.
• Unsealed holes in the return plenum that cause
  depressurization of wall cavities.
• Condensate pan drain lines, internal roof drains,
  or basement sump crocks installed at the highest
  point rather than the lowest.
• Impermeable flooring or moisture-sensitive flooring
  installed on a concrete slab that is releasing too
  much water vapor.

Inspecting moisture control elements as they
are installed is the most important aspect of
supervision—especially in the areas where inspections
may be most difficult. In addition to QA officers
who are employees of the general  contractor or
subcontractor, inspections may be made by third
parties such as construction management or
commissioning firms.

The  inspector must check that the specified  materials
are on site and being installed so they will perform
their function. Sequence is often important in
effective installation. The following items must be
frequently and carefully inspected  during installation:
• The air barrier.
  •  Air barrier materials should be installed so
     they can be easily sealed at the joints and
     penetrations.
  •  Sealants that  complete the air barrier should
     be installed before access to the air barrier is
     blocked.
• Rainwater control.
  •  The shingling of the drain plane and the flashing
     for roof, walls, windows, doors and other
     penetrations should  be correctly installed.
  Insulation.
  •  Insulation should be installed so that it makes
     as complete a layer as possible (i.e., no voids in
     cavity insulation, no uninsulated cavities).
• Plumbing.
  •  The location of plumbing lines should be
     checked.
  •  Cold water lines, chilled water lines and internal
     roof drains should be insulated; pressure tests
     should have been completed prior to installation
     of insulation and enclosing finishes.
  •  Access to valves should be available.
  •  Wet rooms should  be assembled using only
     moisture- and mold-resistant materials.
• HVAC.
  •  Condensate pans should be sloped and plumbed
     correctly.
  •  Access panels should be installed downstream
     of the coils so the coils and ductwork can be
     inspected and cleaned.
  •  Ductwork and return plenums should  be air
     sealed and tested.
  •  Duct insulation should be installed and the
     ductwork sealed.
  •  Chilled water and refrigerant lines should be
     insulated  and  sealed.
• Wet materials.
  •  Materials  that need to  be installed wet or that
     became wet accidentally must be dry before
     cavities are enclosed (e.g., concrete, concrete
     masonry units or porous insulation must be
     dry before they are enclosed by gypsum board
     walls; crawlspaces must be drained and ground
     covering installed before OSB floor decking
     is installed) or flooring (e.g., vinyl flooring on
     concrete slabs) is installed on them.

A number of tests may need to be performed to
demonstrate that a moisture control element is
working properly. Some of the tests are required by
code; some may be specified by the designers in the
construction documents; some may be required to
maintain a manufacturer's warranty and some may
be performed by the  contractor for its  own assurance.
The tests  include:
• Air tightness of the enclosure test (ASTM E779-10,
  ASTM E1827-96 [2002] or ACE [2012]).
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• Air leakage and rain penetration tests on mockups
  or in situ portions of the enclosure (ASTM E783,
  ASTM El 105).
• Water vapor emission test for concrete slabs before
  installing flooring (ASTM F1869)orASTM F2170).
• TAB on exhaust airflows (ASHRAE).
• Pressure test of water supply system  (International
  Plumbing Code Section 312.5).
• Testing the drainage and vent air of plumbing
  systems (International Plumbing Code Section
  312.2, 312.3 and 312.4).
• Drainage tests for condensate drain pans in air
  conditioners. (There are requirements for slope, etc.
  in ASHRAE 62.1.)
• Air pressure difference tests.
• Duct leakage testing (SMACNA).

Documentation of the inspection and testing results
may include the date, location, purpose of inspection,
results, deficiencies and proposed corrective actions;
all items must all be recorded. Each inspection
and test must be documented with log entries,
photographs and checklists. The value of photographs
in documenting an  inspection cannot  be overstated.
Many industry associations offer quality assurance
guidance for building enclosure systems (ABAA,
NCRA, NFRC and RCI). Some offer certification for
those who  provide enclosure consulting and quality
assurance  services  (ABAA, NFRC and  RCI).

This chapter has seven subsections:
• Pre-Construction Planning.
• Site Drainage.
• Foundation Construction.
• Wall Construction.
• Roof and Ceiling Assembly Construction.
• Plumbing System Installation.
• HVAC System Installation.
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  Pre-Construction Planning
                                                                                   www.epa.gov/iaq/moisture
To protect a building from moisture problems during
construction and to ensure the design's moisture
control elements are properly implemented, the
contractor needs to incorporate moisture control
into the planning, scheduling and sequencing of
the project. The contractor also needs to coordinate
these activities with the owner and the owner's
representatives (e.g., the design team, construction
management service or commissioning agent).

Goals

Pre-Construction Planning Goal 1: Develop a moisture
control plan to be used while the building is under
construction.

Pre-Construction Planning Goal 2: Review the
moisture control details in the construction
documents with the design team, construction
management and subcontractors.

Guidance

Pre-Construction Planning Goal 1: Develop a moisture
control plan to follow while the building is under
construction.

Guidance 1: Establish with the owner and design
team the level of concern for moisture control during
construction and after turnover. In developing the
moisture control plan, the contractor can be guided
by the level of concern the owner and design team
express  and by the level of concern implicit in the
construction drawings and specifications for the
design's moisture control elements, third-party
inspections, testing and commissioning.

Guidance 2: Plan the construction schedule and
the sequence of deliveries to meet the owner's  and
design team's  moisture control objectives. Keeping
the building site, building materials and equipment
dry during construction requires extra planning,
effort, equipment and materials. When the entire site
is exposed to the weather and when  the building is
under construction but not yet closed in, moisture-
sensitive materials either must not be on site or must
be protected from the elements. Completely enclosing
the structure before moisture-sensitive materials
and equipment are delivered or are being installed
on lower floors may have a significant impact on the
schedule. The moisture control plan should address at
a minimum:
• Providing construction site drainage: temporary
  drainage, dewatering.
• Providing protection from construction water and
  from leaks from hoses and plumbing.
• Making the enclosure or portions of the enclosure
  weather-tight before the delivery or installation of
  moisture-sensitive  materials.
  • For smaller buildings, the entire enclosure may
    be made weather-tight before sensitive materials
    arrive at the site.
  • For larger buildings, a portion of the enclosure
    may be made weather-tight early enough to
    store or to  begin installing moisture-sensitive
    materials.
  • Before the top floor in high-rise construction is
    reached and roofed, lower floor walls may be
    made weather-tight and floor  decks diked or
    sealed at penetrations (e.g., stairwells, utility
    chases and elevator shafts) and drained at the
    perimeter.
• Providing rain protection for work and for stored
  materials before the building is  closed in.
• Preparing a list of materials that must be kept
  dry, actions planned to protect them during
  construction, and responses if they get wet.
  • Most finish materials (e.g., paper-covered gypsum
    board and  wooden paneling) and some porous
    insulating  materials (e.g.,  fiberglass and cellulose
    insulation) must be kept dry.
• Preparing a plan to store vulnerable materials so
  they are protected  from rain, snow and plumbing
  leaks during construction (e.g.,  schedule delivery
  after the building or a portion of the building is
  weather tight; provide protection independent of  the
  building, such as pallets and tarps, shrink wrap or a
  separate storage building).
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  • Sequence the installation of these materials
    when the building or a portion of the building is
    weather-tight.
• Drying wet materials before finishing or enclosing.
  • Prepare a list of materials that can tolerate
    wetting,  but must be dry before additional
    materials in the foundation can be installed;  the
    critical points by which they must  be dry; actions
    planned  to ensure they are dry at those times;
    and responses  in the event they are wet at a
    critical time.
  • Impermeable materials (e.g., anodized
    aluminum, glass and extruded styrene  foam
    board) can tolerate a great deal of  wetting,  but
    may need to  be dry before sealants or adhesives
    are applied.
  • Some porous materials (e.g., exterior grade
    gypsum board sheathing, plywood and  oriented
    strand board) can tolerate short-term wetting,
    but they must be dry before coatings, tapes,
    adhesives or  interior finish materials are
    applied.  Obtain, read and follow manufacturers'
    instructions.
  • Some porous materials (e.g., concrete, concrete
    masonry units and brick) can tolerate a great deal
    of wetting for extended periods, but must be  dry
    before coatings, tapes, adhesives or interior finish
    materials are applied.  For example, a water-based
    emulsion used  as a spray-applied drain plane
    may not  cure correctly if applied to saturated
    concrete masonry walls. Installing  paper-covered
    gypsum board next to a wet concrete wall can
    result in mold growth on the gypsum board.
• Dehumidifying after closing in the building, but
  before the HVAC system is operational.
• Commissioning and testing the enclosure, plumbing
  and HVAC systems.
• Responding to moisture and mold problems that
  happen in spite of these efforts.
  • Surveillance.
  • Emergency response.
  • Drying, clean-up and repair.
  • Clearance.

Guidance 3: Identify the parties responsible for
implementing each  portion  of the moisture  control
plan.
Pre-Construction Planning Goal 2:  Review the
moisture control details in the construction
documents with the design team, construction
management and subcontractors.

Guidance 1: Review moisture control details in the
construction documents and discuss them with the
design team:
• Review rainwater and subsurface water-control
  details and specifications for the site with the
  landscape and excavation contractors.
• Trace rainwater control, air  barrier and  insulation
  layer details for continuity;  review enclosure testing
  and commissioning requirements (e.g., air pressure
  testing the enclosure).
• Examine the  water vapor dynamics of sections,
  considering the design interior temperature and
  relative humidity and the exterior climate for
  condensation potential and for drying potential.
• Review ice dam  potential in sections and roof
  plans—air barrier, insulation  level, roof venting,
  drainage of snowmelt—where buildings are prone to
  ice dams.
• Review the location of plumbing lines and chilled
  water lines; check cold water and chilled water
  lines for vapor barrier and insulation details; review
  plumbing system commissioning and testing
  requirements (e.g.,  pressure testing, start-up, owner
  training).
• Review enclosure commissioning requirements.
• Review mechanical  systems for:
  •  Indoor humidity control.
  •  Pipe and duct insulation  and vapor control.
  •  Air pressure relationship  requirements (e.g.,
     accidental  depressurization of air-conditioned
     buildings,  rooms  or cavities in hot humid or
     mixed humid climates; accidental pressurization
     of buildings in cold climates).
  •  Location of air conditioning equipment within
     thermal and air enclosures, drain pan slope
     and positive drainage,  insulation specifications,
     adequate room around equipment for proper
     installation of drains, and access panels.
  •  Mold-resistant materials  in custodial closets,
     bathrooms, toilets and other areas that will get
     wet.
• Review mechanical  system  commissioning and
  testing requirements (e.g., test and balance, duct
  tightness testing, start-up and operator training).

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• Review moisture content test procedures before
  installing or closing in porous materials (e.g.,
  concrete).
• Present concerns, cautions and alternatives to the
  owner and design team for discussion and final
  disposition.

Guidance 2: Formalize the results of the discussions
and decisions  made under Guidance 1  into changes
in the construction documents, shop drawings  and
submittals.

Guidance 3: Schedule  required inspection and testing
of moisture control elements (who, when, results
and remedies) so these activities can be completed
while moisture control  details are exposed  and  can be
inspected.
                             www.epa.gov/iaq/moisture
Verification of Pre-Construction Planning

Written meeting notes, modified construction
documents, plans for controlling moisture problems
during construction, planned emergency responses to
moisture problems during construction, and  lists of
the parties responsible for installation, supervision,
inspection, and testing of moisture control design
elements provide verification of the process followed
and the decisions made.
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www.epa.gov/iaq/moisture
 Site Drainage Construction
Issue
Improper site drainage can cause water from rain and
snowmelt to damage the building and its components
during and after construction. Mistakes made in
constructing drainage systems can be difficult and
expensive to fix if they are discovered after structures
are in place. Repeated flooding caused  by poorly
constructed drainage systems can lead to moisture
damage, high insurance costs and increased liability
for building owners.



Site Drainage Goal 1: Water from rain and snowmelt
does not damage the building or its components
during construction.

Site Drainage Goal 2: Water from rain and snowmelt
does not damage the building or its contents after
construction.

Guidance

Site Drainage Goal 1: Water from rain and snowmelt
does not damage the building or its components
during construction.

Guidance 1: Comply with National Pollutant
Discharge Elimination  System (NPDES) requirements
for construction, as implemented by the relevant
authority: U.S. EPA,  state government or local
government.20 Determine whether there are
applicable state  or local erosion, sediment control
and storm water management requirements.
Obtain local erosion, sediment control and storm
water management permits, as necessary, prior to
construction.

Guidance 2: Comply with design requirements for
maintaining water management during construction.
If design requirements are not provided, comply with
the following recommended minimum.
Minimize potential for runoff:
• Avoid clearing or grading stream buffers; forest
  conservation areas; wetlands, springs and seeps;
  soils highly susceptible to erosion; steep slopes;
  environmental features; and runoff infiltration
  areas.
• Group construction activities into phases to limit
  soil exposure.  Limit activities to the current phase
  to decrease  the time soil is exposed.
• Begin immediate efforts to stabilize exposed soils.
  While the long-term goal is to establish permanently
  stabilized soils, mulching, hydro-seeding or erosion
  control matting may provide short-term protection.
• Avoid cuts and grading of steep slopes—greater
  than 15 percent—wherever possible.  If a steep
  slope exists, diversions or a slope drain should  be
  used so all water flowing onto the slope is directed
  away from the site to approved  disposal areas.
• Train construction staff in storm water management
  practices.
• Ensure positive drainage principles are met so water
  drains from  the site and away from the structure:
  •  Make certain water is moved away from the
     building.
  •  Ensure water is not allowed to pond at low points
     or in low areas, unless planned for.
  •  Make sure obstructions around the building and
     site (e.g., dirt and gravel stockpiles, silt fencing)
     do not cause water to back up into the building.
• Institute storm water management supervisory
  roles and  responsibilities by clearly describing
  each contractor's responsibilities. Specify who will
  inspect the features and  how often.21

Site Drainage Goal 2: Water from rain  and snowmelt
does not damage the building or its contents after
construction.
20 See http://cfpub.epa.gov/npdes/stormwater/authorizationstatus.cfm to determine whether EPA or your state is the relevant authority. See http://cfpub.epa.gov/npdes/stormwater/
const.cfm for the federal requirements. Accessed November 6, 2013.

21 For more information see http://cfpub.epa.gov/npdes/stormwater/menuofbmps/ index.cfm?action=min measure&min measure id=4. Accessed November 6, 2013.

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Guidance 1:  Identify the water control elements
of the site design, such as finish grading and
sloping requirements, and the  infiltration, retention
or detention controls. Work with the design team
to interpret and modify the drainage systems if
necessary.

Guidance 2:  Ensure drainage systems are installed or
constructed as specified in the construction document
by supervising, inspecting and documenting
construction and installation of the site water control
elements. Examples  include:
• Determining finished grade slope around the
  building foundation by measuring the change in
  height over distance.
                             www.epa.gov/iaq/moisture
• Documenting grades and slopes for drainage
  systems.

Guidance 3:  Ensure all temporary water control
systems, such as silt fences, have been removed.

Verification of Site Drainage Construction

Create and use inspection checklists to document
construction and installation. The material in this
chapter can be helpful in identifying items to  include
in such checklists.
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www.epa.gov/iaq/moisture
  Foundation  Construction
Issue
As the interface between a building and the
supporting soil, most foundation materials can
tolerate wet conditions for long periods of time
without deteriorating.  However, the foundation must
be dry enough to permit the installation of damp-proof
coatings and materials used to form the insulation,
air barrier, vapor control and finish portions of the
foundation walls and floors. Failure to  properly
construct a foundation can lead to problems that
are extremely difficult and expensive to fix once a
building is constructed.




Foundation Construction Goal 1:  Keep foundation
assembly materials dry during construction.

Foundation Construction Goal 2:  Construct
foundations to effectively implement the moisture
control systems in the design drawings and
specifications.

Foundation Construction Goal 3:  Prepare operation
and maintenance materials regarding continued
effective moisture protection for foundations.

Guidance

Foundation Construction Goal 1:  Keep foundation
assembly materials dry during construction.

Guidance  1: Implement the moisture control  plan for
the construction phase, which should cover:
• Site drainage to control water in foundations during
  construction.
• Response strategies for water problems that occur
  during construction (e.g., have pumps available for
  emergency response to heavy rains).
• Drying concrete and masonry walls and slabs before
  installing interior wall  insulation, interior gypsum
  board wall covering and  interior slab finishes.
• Preventing high-humidity conditions when crawl
  spaces are enclosed by the overhead floor deck by:
  • Sloping the earth in the crawl space to direct
    water to a disposal location; installing a vapor
    barrier over the earthen floor as soon  as possible.
    NOTE: If the crawl space has a concrete slab, the
    vapor barrier will be part of the slab detailing.
  • Monitoring the relative humidity to determine
    whether dehumidification is needed;  controlling
    humidity in the crawl space to less than 65
    percent RH using ventilation, if outdoor air dew
    points are lower than 55°F,  or with dehumidifiers.
• Designate someone to conduct concrete moisture
  content or water vapor emission tests. Document
  tests, results and remedies. Appendix C contains
  an overview of testing the  moisture content of
  materials during construction.

Foundation Construction Goal 2: Construct
foundations to effectively implement the moisture
control systems in the design drawings and
specifications.

Guidance  1: Install foundation rainwater control,
insulation, air barrier and water  vapor control in
accordance with construction documents. Implement
quality assurance program for:
• Exterior drainage and foundation wall damp-proof
  coatings.
• Capillary breaks at footings and at the top of the
  foundation wall.
• Insulation, air barrier and water vapor control.
• Air barrier and thermal  insulation systems.

Foundation Construction Goal 3: Prepare operation
and maintenance materials regarding continued
effective moisture protection for foundations.

Guidance  1: Provide—or direct contractors,
subcontractors or manufacturers to provide—
operation and maintenance information required to
maintain moisture control elements of the foundations
including:
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• Signs of foundation drainage or damp-proofing
  failure.
• Frequency of inspection.
• Method of repairing problems.

Verification of Foundation Construction

• Document quality assurance programs for the
  installation of the hygrothermal control elements
  of the enclosure. Document inspection quality
  assurance testing and functional tests with field
                           www.epa.gov/iaq/moisture
log books, test results and photographs. The
parties identified in the construction documents
or contracts should conduct testing as required
by the design or for internal  quality assurance.
Archive the installation documentation, checklists,
photographs, log books and test results. Provide
required incidental labor, materials and equipment
to support third-party testing.
Develop written operations and maintenance
information, as required by contract.
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www.epa.gov/iaq/moisture
 Wall  Construction
Issue
Care must be taken during wall construction to
keep moisture-sensitive construction materials dry.
Moisture-sensitive wall materials that get wet during
construction may grow mold, corrode or deteriorate.
Walls must be constructed according to design
specifications to incorporate moisture and mold-
prevention measures.

Goals
Wall Construction Goal 1:
during construction.
Keep wall materials dry
Wall Construction Goal 2: Construct walls to
effectively implement moisture control systems in the
design drawings and specifications.

Wall Construction Goal 3: Prepare operation and
maintenance materials regarding continued effective
moisture protection for walls.

Guidance
Wall Construction Goal 1:
during construction.
Keep wall materials dry
Guidance 1:  Take the steps developed in the
moisture control plan to ensure that materials meant
to remain dry, stay dry. Examine and reject materials
that arrive contaminated with mold. Store materials in
a clean, dry area protected from water (e.g.,  covered
and raised on pallets). Test the moisture content of
porous materials (e.g., those that can easily store
a great deal of liquid water) before closing them in
cavities or applying adhesives or finishes to them.

Guidance 2:  Document moisture control efforts
undertaken during construction.

Wall Construction Goal 2:  Construct walls to
effectively implement moisture control systems in the
design drawings and specifications.
• Guidance 1:  Install moisture control elements
  designed to meet the criteria specified in the
  construction documents. Implement quality
  assurance programs for the hygrothermal control
  systems. Provide required incidental labor,
  materials and equipment to support third-party
  testing.

Inspect and verify moisture, air and heat flow control
details at these vulnerable locations:
• Cladding.
• Flashing above and below windows, doors and
  intake  and exhaust openings.
• Through-flashing details where a lower story roof,
  balcony or deck intersects upper story walls.
• Building drain planes: weather-resistant-barriers,
  felt-paper and spray-applied membranes.
• Insulation layer:  Inspect the insulation layer for
  continuity.
• Air barrier: Air seal and insulate wall and ceiling
  areas that will be made inaccessible by  interior
  framing or fixtures. These areas include:
  • Staircases, bathtubs, showers and cabinets
    installed against exterior walls.
  • Soffits beneath  insulated ceilings, where interior
    walls meet exterior walls.
  • Areas around elevator and stair shafts.
  • Air seal and insulate around windows and doors
    before applying  interior finishes.
  • Plan air-sealing  activities (e.g., caulking and
    foaming) so they can be performed and inspected
    easily and efficiently.
• Sequence delivery and installation of materials so
  the critical elements of moisture protection can be
  installed readily. For example,  in a wall constructed
  with  a  brick veneer/foam  board insulation/spray-
  applied membrane drain  plane-air barrier/concrete
  masonry wall, the  membrane must be applied
  before  the foam board, and the foam board applied
  before  the brick veneer is installed. All these
  materials must be on site and subcontractors must
  be scheduled, or else a wall or portions of a wall
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  may end up without the spray-applied membrane or
  foam insulation behind the brick veneer.

Wall Construction Goal 3:  Prepare operation and
maintenance materials regarding continued effective
moisture protection for walls.

Guidance 1: Provide or direct contractors,
subcontractors or manufacturers to provide operation
and maintenance information required to maintain
moisture control elements of the wall assemblies
including:
• Identifying signs of cladding failure.
• Inspection frequency.
• Method of repairing problems.
                             www.epa.gov/iaq/moisture
Verification of Wall Construction

• Document quality assurance programs for the
  installation of the hygrothermal control elements
  of the enclosure. Document inspection quality
  assurance testing and functional tests with field
  log  books, test results and photographs. The
  parties identified in the construction documents
  or contracts should conduct testing as required
  by the design or for internal quality assurance.
  Archive the installation documentation, checklists,
  photographs, log books and test results.
• Develop written operations and maintenance
  information, as required by contract.
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www.epa.gov/iaq/moisture
  Roof  and Ceiling Assembly  Construction
Issue
Construct roof assemblies according to design
specifications that incorporate moisture- and mold-
prevention measures. Take care to keep moisture-
sensitive materials dry during construction.  Moisture-
sensitive roof assembly materials that get wet during
construction may grow mold, corrode or deteriorate.

Goals

Roof Construction Goal 1: Keep roof assembly
materials dry during construction.

Roof Construction Goal 2: Construct roof assemblies
to effectively implement the moisture control systems
in the design drawings and specifications.

Roof Construction Goal 3: Prepare operation and
maintenance materials concerning continued effective
moisture protection for roof assemblies.

Guidance

Roof Construction Goal 1: Keep roof assembly
materials dry during construction.

Guidance 1: Follow the steps in the  moisture control
plan to ensure that materials meant  to remain dry,
stay dry. Examine and reject materials that arrive
contaminated with mold. Store materials in  a clean,
dry area protected from water (e.g., covered and
raised on pallets). Test the moisture  content of porous
materials (e.g., those that can easily store a great
deal of liquid water) before  closing them in  cavities or
applying adhesives or finishes to them.

Roof Construction Goal 2: Construct roof assemblies
to effectively implement the moisture control systems
in the design drawings and specifications.

• Guidance  1: Properly install the moisture  control
  elements designed to meet the criteria specified
  in the construction documents. Implement
  quality assurance programs for the hygrothermal
  control systems. Provide required incidental labor,
  materials and equipment to support third-party
  testing.

• Inspect and verify details to control moisture, air
  flow and heat flow at these vulnerable locations:
  • Roofing — slope, installation.
  • Flashing at roof edges, gutters, roof drains,
    valleys,  chimneys, dormers, skylights, equipment
    curbs, pipe penetrations, structural support for
    railing, signs, fences and screens.
  • Through-flashing details where a lower story roof
    intersects upper story walls.
  • Roofing paper, peel-and-stick bituminous
    membranes.
  • Insulation layer — inspect for continuity.
  • Soffit and roof peak ventilation openings, air
    sealing and insulation details for vented roofs
    that pitch to  eaves.
  • Air barrier:
    • Air seal the joints between materials that form
      the air barrier (e.g., foam board,  gypsum board
      thermal barrier and concrete plank or poured
      concrete roof deck). NOTE: Fluted  metal decks
      are difficult to use as an air barrier and require
      special detailing in order to be used as one.
      Air seal between the roof air barrier material
      and the wall air barrier material.
    • Air seal and insulate the edge of fluted
      metal decks, parapet wall, equipment curbs,
      skylights, gaps around elevator shafts and other
      areas  that will be made inaccessible by interior
      framing, equipment hung from ceilings, pipes,
      ducts and ceilings.
      Plan air-sealing activities (e.g., caulking
      and foaming) so they can be performed and
      inspected easily and efficiently.
      •  Sequence the delivery and installation of
        materials so the critical elements of moisture
        protection can be readily installed. For
        example, if the air barrier in  a  low-slope roof
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        system is to be made using two layers of
        foam board sheets with the joints staggered
        and taped, it is critical that the correct tape
        is on  hand when the foam board is being
        placed.
      •  Plan air-sealing efforts (e.g., caulking,
        foaming  and  membrane installation) so they
        can be accomplished and inspected  easily
        and efficiently.

Roof Construction Goal 3: Prepare operation  and
maintenance materials concerning continued effective
moisture protection for roof assemblies.

Guidance  1:  Provide or direct contractors,
subcontractors or manufacturers to provide operation
and maintenance information required  to maintain
moisture control elements of the roof assemblies. The
builder's responsibilities should be spelled out in the
contracts and  may include:
• Signs of roofing and roof penetration failure.
• Frequency of inspection.
• Method of repairing problems.
                             www.epa.gov/iaq/moisture
Verification of Roof and Ceiling Assembly
Construction

• Document quality assurance programs for the
  installation of the hygrothermal control elements
  of the enclosure. Document inspections,  quality
  assurance testing and functional tests with field
  log  books, test results and photographs. The
  parties identified in the construction documents
  or contracts should conduct testing as required
  by the design or for internal quality assurance.
  Archive the installation documentation, checklists,
  photographs, log books and test results. Provide
  required  incidental  labor, materials and equipment
  to support third-party testing.
• Develop written operations and  maintenance
  information, as required by contract.
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  Plumbing System Installation
Issue
Plumbing-related water problems can occur as
the result of leaks and other accidental releases
of plumbing water from charged systems during
construction. Delayed problems can occur because of
errors in  installing water supply lines, drain lines and
appliances.

Goals

Plumbing System Installation Goal 1: Install water
supply lines, drain  lines and appliances to prevent
pre- and  post-occupancy leaks  and to facilitate the
discovery and repair of  problems during construction
and post-construction occupancy.

Plumbing System Installation Goal 2: Install pipe
insulation and water vapor controls on cold water  lines
and appliances.

Plumbing System Installation Goal 3: Install materials
that will minimize mold growth in unavoidably wet
areas.

Plumbing System Installation Goal 4: Prepare
operation and maintenance materials concerning
continued effective moisture protection for plumbing
systems.

Guidance

Plumbing System Installation Goal 1: Install water
supply lines, drain  lines and appliances to prevent
pre- and  post-occupancy leaks  and to facilitate the
discovery and repair of  problems during construction
and post-construction occupancy.

Guidance 1: Review construction documents and
prepare shop drawings and submittals that ensure
pipes are not located in exterior walls and ceilings
that contain porous insulation.  NOTE: If pipes
must be located in an exterior wall or ceiling,
install a continuous, air-sealed  layer of closed-cell
foam insulation between the  pipe and the exterior
sheathing, curtain wall  or roof deck. Schedule
installation so testing can be done before piping and
components are closed in. This may require separately
testing sub-sections of the plumbing systems.

Guidance 2: Follow construction documents when
installing plumbing systems.

Guidance 3: Install plumbing so that it is easy to
access and repair. Orient valves, pipes and  other key
components in locations where leaks will be easily
noticed and that are most accessible for inspection
and repair.  Where appropriate, label key components
or affix instructions and diagrams to aid others
in accessing and repairing plumbing. These aids
may include diagrams of flow directions and valve
locations and functions.

Plumbing System Installation Goal 2: Install pipe
insulation and water vapor controls on cold water lines
and appliances.

Guidance 1: Install plumbing system insulation and
water vapor controls in accordance with construction
documents. Protect porous insulating and paper-
based water-vapor-control materials from rainwater.

Plumbing System Installation Goal 3: Install materials
that will minimize mold growth in unavoidably wet
areas.

Guidance 1: Install moisture-and mold-resistant
materials in unavoidably wet spaces in accordance
with design documents.

Plumbing System Installation Goal 4: Prepare
operation and maintenance  materials concerning
continued effective moisture protection for  plumbing
systems.

Guidance 1: Provide or direct contractors,
subcontractors or manufacturers to provide operation
and maintenance information required to maintain
plumbing systems, appliances, fixtures and moisture-
resistant materials used in wet rooms. Among the
topics that  should be covered are potable water,
bathing and wash water, waste water, hydronic heating

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systems, chilled water cooling systems, spa and pool
systems, washrooms, custodial closets and locker
rooms. The builder's responsibilities for training
materials should be spelled out in the contracts and
may include:
• Signs of plumbing system failure and hydronic
  heating and cooling system failure.
• Frequency of inspection.
• Method of repairing problems.

Verification  of Plumbing System Installation

• Inspect installation of plumbing system insulation
  and water vapor controls. Document inspections
  with field  log books and  photographs. Quality
  assurance is crucial to ensure complete coverage
  with insulation and water vapor control on joints
  and seams and where pipes interface with other
  equipment (e.g., pumps, valves, tanks). Document
  the inspections with signed checklists, log books
  and photographs.
• Inspect plumbing for acceptability of installation
  and materials, for compliance with design
  documents, and for access to lines before
                           www.epa.gov/iaq/moisture
performing tests. Use installation checklists and
provide signed documentation of all test results.
Pressure test water supply lines while they are
exposed for inspection (i.e., before they are
enclosed or insulated). At a minimum, pressure
test water supply lines according to section 312.5
of the International Plumbing Code or the relevant
sections of applicable local codes.
Test the drain and vent side of the  plumbing system
when all lines are exposed for easy inspection and
repair in accordance  with design specifications
and as required by relevant building codes. At a
minimum, gravity test the drain and vent side of
the system according to sections 312.2, 312.3
and 312.4 of the  International Plumbing Code or
relevant sections of other applicable local codes.
Inspect plumbing and surrounding fixtures located
in unavoidably wet areas to ensure the use of
moisture- and mold-resistant materials. Document
the inspections with signed checklists, log books
and photographs.
Develop written operations and maintenance
information, as required by contract.
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www.epa.gov/iaq/moisture
  HVAC  System  Installation
Issue
Improper installation of HVAC systems can create
condensation and moisture-control problems.
Examples include:
• Inadequate dehumidification and pressurization
  performance of the HVAC system, which can lead to
  occupant discomfort and mold growth.
• Condensation on HVAC equipment components,
  which can damage components, increase
  maintenance costs, decrease component and
  system lifespan and lead to mold growth.
• Inadequate drainage of collected condensate or
  other water, which can result in moisture damage to
  the building and its contents and to mold growth.
• Inadequate ventilation of indoor humidity sources
  (e.g., showers, bathrooms, spas and kitchens),
  which can lead to mold growth and deterioration.




HVAC System Installation Goal 1: Keep HVAC
equipment and materials dry during construction and
provide temperature and humidity control as required
during the close-in phase of construction.

HVAC System Installation Goal 2: Install HVAC
systems to effectively implement moisture control as
specified in the design drawings and specifications.

HVAC System Installation Goal 3: Prepare operation
and maintenance materials for continued performance
of HVAC system moisture control.

Guidance

HVAC System Installation Goal 1: Keep HVAC
equipment and materials dry during construction and
provide temperature and humidity control as required
during the close-in phase of construction.

Guidance 1: Plan when and how  the HVAC
equipment will be energized and used during
construction. Plan the required inspection and
testing—who, when, results and remedies—so these
activities can be completed before the plumbing,
ductwork and other components are closed in. In
addition, plan the installation sequence so testing can
be done before system components are closed in.

Guidance 2: Take steps to ensure that equipment
and materials meant to remain dry, stay dry. Prepare a
list of equipment and materials that must be kept dry,
actions planned to protect them during construction,
and responses if they get wet.
• Schedule the delivery of  HVAC system  components
  so they can be protected immediately from
  rainwater and plumbing leaks. Uninsulated,
  galvanized ductwork can tolerate some  wetting,
  but air handlers, insulated components, electronic
  components, chillers, compressors and controls all
  need positive protection from weather and moisture.
• Schedule the installation of  HVAC components for
  when the building or a portion of the building has
  been made weather-tight.
• Inspect insulated ductwork and components for
  moisture damage and mold growth when they are
  received and before they are installed.

Guidance 3: Control  temperature and humidity during
the close-in phase of construction. Plan the transition
from unconditioned interior space to conditioned
interior space in conjunction with the designers and
owners:
• Identify situations and processes that will require
  humidity control for installation and drying of
  materials. For example, concrete slabs  may need
  to  be dried before  finish flooring goes down; below-
  grade concrete walls may need to be dry before
  interior insulation  and finishes are installed;
  and temperature and humidity may need to be
  controlled before painting or varnishing takes place.
• Use the permanent HVAC systems to provide
  required conditioning, if  possible. Follow the
  guidance in Duct Cleanliness for New Construction
  Guidelines (SMACNA 2010).
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• If the permanent HVAC equipment cannot be
  used, plan for temporary heating, cooling and
  dehumidification. NOTE: Non-vented combustion
  devices add a great deal of water vapor as well as
  heat to a space and cannot be used  to dehumidify.

HVAC System  Installation Goal 2: Install HVAC
systems to effectively implement moisture control
systems in the design drawings and specifications.
Implement quality assurance programs for the
hygrothermal  control  systems.  Provide  required
incidental labor, materials and equipment to support
third-party testing.

Guidance 1: Plan  required inspections—who, when,
results and remedies—so they can be completed
before HVAC components, particularly  the distribution
systems, are closed in.

Guidance 2: Install HVAC systems, condensation
collection and drainage systems, system insulation,
air barriers and water vapor controls in accordance
with construction  documents.

Inspect the installation of:
• Drain pans,  drain pan outlets, traps and disposal.
• HVAC ductwork including seams and sealing prior
  to the installation of duct insulation.
• Insulation and vapor retarders on exposed surfaces
  that are expected to be below the dew point of
  ambient air  (e.g., chilled water lines, refrigerant
  lines, air conditioning air handlers and chillers),
  especially at transitions (e.g., penetrations through
  walls, floors and ceilings; support clamps; valves;
  dampers; pumps; blowers; and gauges).
• Access panels to allow inspection  and maintenance
  of HVAC components (e.g., air handlers, filters,
  coils, drain pans and the supply duct near the air
  handler).
• Exhaust ventilation systems for duct sealing,
  insulation and vapor control.

HVAC System  Installation Goal 3: Prepare operation
and maintenance  materials for continued performance
of HVAC system moisture control.
                             www.epa.gov/iaq/moisture
Guidance  1:  Provide or direct contractors,
subcontractors or manufacturers to provide operation
and maintenance information required to maintain
moisture control elements of the HVAC system
components.  The builder's responsibilities should be
spelled out in the contracts and may include:
• Requirements for filters, coils, condensate drainage
  systems, ductwork, piping,  insulation and vapor
  barriers, pumps, valves, fans, belts, lubrication and
  controls.
• Frequency  of inspection.
• Methods of repairing problems.

Verification of HVAC System Installation

• Write a  plan for moisture control in regard to
  HVAC equipment and dedicated drying equipment
  during construction.  Use photographs, log books
  and written reports to document moisture-control
  activities, water problems and responses to water
  problems.
• Parties  identified in the construction documents or
  contracts should perform tests as required by the
  design or for internal quality assurance. These tests
  include:
  • Creating air pressure difference maps for each
    mode of  operation.
  • Testing for air duct tightness target—before
    installation of ductwork insulation.
  • Testing drainage of condensate drain pans in air
    conditioners.
  • Testing,  adjusting  and  balancing the HVAC
    system as designed.
  • Performing other tests and inspections required
    by the commissioning plan.
• The tests and inspections should be documented
  with field log books,  moisture content  and vapor
  emission tests, and photographs.
• Develop written operations and maintenance
  information, as required by contract.
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REFERENCES
American Society for Testing and Materials. 2003. Standard test
    method for determining air leakage rate by fan pressurization.
    E779-03. Pennsylvania. American Society for Testing and
    Materials.

American Society for Testing and Materials. 1996. Standard
    test methods for determining airtightness of buildings using
    an orifice blower door. E1827-96. Pennsylvania. American
    Society for Testing and Materials.

American Society of Heating, Refrigerating and Air-Conditioning
    Engineers. 2004. ASHRAE Handbook of Fundamentals.
    Ventilation for Acceptable Indoor Air Quality. Standard 62.1.
    Atlanta, GA: American Society of Heating, Refrigerating and
    Air-Conditioning Engineers.
    (The ASHRAE ventilation standard provides information
    needed to determine ventilation  rates for differing
    occupancies plus a number of design, operation and
    maintenance requirements to ensure proper performance
    of ventilation equipment. Section 6.2.8 specifically deals
    with  exhaust ventilation. Standard 62.1 applies to many
    situations.)

International Code Council. 2003.  ICC International Plumbing
    Code. Sections 312.2 -312.5. Washington, DC: International
    Code Council.
    (Sections 312.2 to 312.5 of these codes  specify a gravity
    test of the drain and vent side of plumbing systems.)
Mold Litigation Task Force of the Associated General Contractors
    of America, Inc. 2003.  Managing the risk of mold in the
    construction of buildings. CONSTRUCTOR, http://www.agc.
    org/galleries/conrm/may03  mold.pdf. Accessed November 6,
    2013.

United States Environmental Protection Agency.  2005.
    Authorization Status for EPA's Stormwater Construction and
    Industrial Programs: States, Indian Country and Territories
    Where EPA's Construction General Permit (CGP) and Multi-
    Sector General Permit (MSGP) Apply. Washington, DC:
    United States Environmental Protection Agency. http://cfpub.
    epa.gov/npdes/stormwater/authorizationstatus.cfm. Accessed
    November 6, 2013.
    (This website outlines the relevant authority—U.S.
    EPA, state, or local government—for compliance with
    National Pollutant Discharge Elimination System  [NPDES]
    requirements for construction in a given state.)

United States Environmental Protection Agency.  2006.
    Construction Site Stormwater Runoff Control. Washington,
    DC: United States Environmental  Protection Agency, http://
    cfpub.epa.gov/npdes/stormwater/menuofbmps/index.
    cfm?action=min measure&min  measure id=4. Accessed
    November 6, 2013.
    (This website outlines best management practices [BMPs] for
    controlling storm water  runoff at construction sites.)

United States Environmental Protection Agency.  2006.
    Stormwater Discharges  from Construction Activities:
    Overview. Washington, DC:  http://cfpub.epa.gov/npdes/
    stormwater/const.cfm. Accessed November 6,  2013.
    (This website outlines the federal  requirements for complying
    with National Pollutant  Discharge Elimination  System
    [NPDES] requirements for construction.)
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                                                                          www.epa.gov/iaq/moisture
 Chapter 4: Operating and Maintaining  Moisture-Controlled
                 Environments
 INTRODUCTION

The people who keep buildings working—the HVAC
mechanics, carpenters, plumbers, electricians,
engineers, custodians and managers—inherit the
good points and the bad points of the design and
construction.

This chapter consists of the following sections:
• Site Drainage Maintenance.
• Foundation Maintenance.
• Wall Maintenance.
• Roof and Ceiling Assembly Maintenance.
• Plumbing System Operation and Maintenance.
• HVAC System Operation and Maintenance.
Each section is concerned with regular inspection; the
cleaning, lubrication, repair or replacement that may
result from the inspection;  and the documenting of
inspections and responses. Several of these sections
require the development of specific operation and
maintenance plans. The section-specific plans can be
assembled into a master moisture-control plan.
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Table 4-1  Troubleshooting Common  Indoor Water Problems
   SYMPTOMS    MOISTURE PROBLEM
 Mold growth
 Peeling paint

 Wood decay

 Corrosion
 Plumbing leaks
 and spills
 Water travels to
 materials that
 cannot tolerate
 wetting
Leaks in the building
enclosure due to problems
with rain and groundwater
controls
                   Insufficient
                   dehumidification by HVAC
                   system'31
                   Condensation on dirty
                   surfaces inside HVAC
                   systems
                   Wet materials enclosed in
                   building assemblies
Leaks in the building
enclosure due to problems
with rain and groundwater
controls
Improper design

Improper installation
during construction

Improper operations and
maintenance practice
Capillary action (water
wicks through porous
building materials such as
concrete or wood)
                                                       POTENTIAL CAUSES
                                   DESIGN         I     CONSTRUCTION
Missing or poorly designed   Missing flashing or
details                     building wrap

                           Incorrect sloping

                           Damaged sub-grade
                           drainage

Air conditioning equipment   Failure to properly wire
oversized                   humidity sensors

Air conditioning equipment
not designed for sufficient
dehumidification at design
and part load
                           Poor condensate drain
                           design
Air handler inside surfaces
insulated or hard to clean
Moisture-sensitive
materials shown touching
porous materials that are
likely to get wet

No values for moisture
content or emission given
in the specifications
Missing or poorly designed
details
Locating water lines in
a space that reaches
freezing temperatures

Poorly designed shower
pan

Moisture barrier omitted
from building design

Drainage layer beneath
slab omitted from building
design
                                                     Flooring placed on slab
                                                     while it is too damp

                                                     Vapor emission tests on
                                                     slab  may not have been
                                                     conducted
Missing flashing or
building wrap

Incorrect sloping

Damaged sub-grade
drainage

Defective pipe joining

Accidental penetration
of pipe by one or more
dry wall screws
Moisture barrier
not installed during
construction

Drainage barrier
not installed during
construction
                           Failure to identify and
                           repair settled grading near
                           foundation

                           Damaged flashing on
                           rooftop air handler curb

                           Missing shingles
                           Chilled-water temperature
                           set-point too warm

                           Economizer set-point that
                           allows introduction of
                           humid outdoor air

                           Continuously running
                           air handler regardless of
                           cooling demand
                           Failure to clean HVAC
                           system cooling coils

                           Clogged drain  pan

                           Failure to seal penetrations
                           during maintenance, repair
                           or installation  of new
                           equipment
Failure to identify and
repair settled grading near
foundation

Damaged flashing on
rooftop air handler curb

Missing shingles
Failure to inspect
plumbing and repair
problems

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Table 4-1 Continued
   SYMPTOMS     MOISTURE PROBLEM
 Condensation
 Delamination
 Improper curing
Warm, moist outside air
enters enclosure through
cracks and holes during
warm, humid weather*1
                   Warm, moist indoor air
                   leaves enclosure through
                   cracks and holes during
                   cold weather*1
                   Vapor barriers installed
                   improperly in exterior walls
Non-vented or poorly
vented moisture sources
(e.g., swimming pools,
spas, aquariums,
dishwashers, combustion
devices, kitchens and
showers)
Wet materials enclosed in
building assemblies
                                                      DESIGN
Air barrier omitted from
building design

Building design did not
call for positive pressure
operation of the building
Air barrier omitted from
building design

Air barrier detailed for attic
assembly is impossible to
install

Building designed to
operate at positive
pressure in an extremely
cold climate
Vapor barrier specified
on both sides of a wall
assembly

Vapor barrier specified on
interior surfaces in hot,
humid climates

HVAC system design
omitted exhaust ventilation
for moisture sources

Insufficient exhaust
ventilation  specified in
HVAC system design
Moisture-sensitive
materials shown touching
porous materials that are
likely to get wet

No values for moisture
content or emission given
in the specifications
                                                        POTENTIAL CAUSES
                                                          CONSTRUCTION
Controls poorly
implemented during
construction (e.g.,
concrete block left out of a
soffit area)

Air barrier installed poorly

Holes cut in well-installed
air barrier to permit
passage of wire, conduit
or ducts
Unintentional vapor
barriers such as vinyl
wall covering, mirrors or
blackboards installed on
inside of exterior walls in
hot, humid climate (can
create a vapor barrier on
the cold side of the wall)
Exhaust duct leaks

Poor balancing on
multiple-inlet exhaust
systems

Exhaust dampers closed
Flooring placed on slab
while it is too damp

Vapor emission tests on
slab may not have been
conducted
                                                                                  Failure to reseal access
                                                                                  holes cut through an
                                                                                  assembly

                                                                                  Changes in HVAC
                                                                                  system operations cause
                                                                                  building to run at positive
                                                                                  pressurization
                                                                                  Vinyl wall covering, mirrors
                                                                                  or blackboards added on
                                                                                  inside of exterior walls in
                                                                                  hot, humid climate (can
                                                                                  create a vapor barrier on
                                                                                  the cold side of the wall)
                                                                                                     Broken belt in a fan

                                                                                                     Clogged exhaust grilles or
                                                                                                     ducts
(a)This problem may also occur during the bidding, contract negotiation or value engineering phases of a project when, for example, different air
conditioning equipment is substituted for the equipment called for in the design.

(b)The air leak may be due to holes in the enclosure made by occupants, contractors or maintenance personnel, or it may have been caused by changes
in the control sequence of outdoor air and exhaust systems.

(c)The problem of indoor condensation can be greatly aggravated if there are large sources of humidity inside the building.
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www.epa.gov/iaq/moisture
 Site  Drainage  Maintenance
Issue
Failure to maintain drainage systems can lead to
unexpected flooding during events of heavy rain or
snowmelt, causing extensive property damage.




Site Drainage Goal 1: Facility maintenance systems
and preventive maintenance plans effectively address
site drainage.

Site Drainage Goal 2: All runoff from parking lots,
sidewalks and other impermeable or low-permeability
surfaces is diverted to a designed drainage system.

Site Drainage Goal 3: Future site development or
building modifications or additions do not interfere
with existing site drainage systems.


Guidance

Site Drainage Goal 1: Facility maintenance systems
and preventive maintenance plans effectively address
site drainage.

Guidance 1: Develop and implement a preventive
maintenance plan for landscaping and  engineered
structures. The purpose of the plan is to ensure that
all drainage systems serve the purpose for which they
were designed. The plan should  include:
• An introduction and general information.
  • Name and contact information for persons
    responsible for operation and  maintenance.
  • A narrative overview describing the site and the
    theory of operation of the drainage systems.
• A definition of the inspection requirements for each
  drainage feature.
  • Inspection frequency should be specified (See
    Appendix C).
  • What to look for.
• Definitions of the maintenance activities necessary
  to keep each drainage feature operating as
  intended.  Examples include:
  • Cleaning debris from diversion systems to prevent
    water flow from being obstructed.
  • Removing sediment from the bottom of swales
    (See Appendix F for sample checklists).
• Maintenance agreements and contacts. If
  contractors are responsible for some or all of the
  maintenance requirements, list the contractors'
  names, contact information and responsibilities.

Guidance 2: Develop and implement a preventive
maintenance plan to  maintain parking lots, sidewalks
and other impermeable surfaces.
• Read, understand and comply with the designer's
  inspection and maintenance requirements or best
  management practices for impervious surfaces.
• Develop an inspection checklist and logbook (See
  Appendix F for sample checklists).

Site Drainage Goal 2: All runoff from parking  lots,
sidewalks and other impermeable or  low-permeability
surfaces is diverted to a designed drainage system.

Guidance 1: Ensure that actions such as plowing
snow from sidewalks and parking lots do not obstruct
drainage or pile snow against the building.

Guidance 2: Inform all  lawn-care subcontractors  and
landscapers  about drainage systems  on the site so
their work does not interfere with the drainage. Have
them watch for drainage problems as they work.

Site Drainage Goal 3: Future site development or
building modifications or additions do not interfere
with existing site drainage systems.

Guidance 1: Make sure changes such as additional
parking areas (even dirt parking areas) do not
overburden existing system capacity  or redirect runoff
into buildings. Even small projects such as adding
planters or walkways can affect infiltration capacity
and redirect runoff.


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Guidance 2: Persons charged with maintaining           Verification of Site Drainage Maintenance
drainage systems should participate in the design of
any development or building modification.               KeeP and maintain records of all inspections,
                                                      including completed checklists. Include photographs
                                                      and test reports so that changes in conditions can be
                                                      verified.
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www.epa.gov/iaq/moisture
 Foundation Maintenance
Issue
Rainwater and snowmelt can cause unwanted
moisture intrusion through the foundation of a
building. Foundations are vulnerable to chronic
moisture problems from rainwater, ground water,
plumbing leaks, and condensation. Regular
inspection, particularly of areas not ordinarily
occupied, is critical to reduce the risk of serious
damage to the foundation and the risk of adverse
health effects to the occupants.




Foundation Drainage Goal 1: Foundation drainage
systems divert water away from the structure.

Guidance

Foundation Drainage Goal 1: Foundation drainage
systems divert all water away from the structure.

Guidance 1: Inspect the exterior of the foundation
and the surrounding landscape.
• Check whether the surrounding landscape diverts
  water away from the building envelope. Note any
  soil settlement or pooled rainwater.
• Check the condition of roof drain leaders.
• Inspect the foundation for changes in existing
  cracks and for new cracks that might indicate water
  problems.
• Inspect the intersection and slope  of sidewalks,
  patios and pavements with the adjoining building
  for potential seepage.
• Look for newly sprouted or planted trees near drain
  lines. Remove or prune as  needed.
• Check exterior plumbing fixtures, hoses and
  irrigation lines for  leaks.
• Conduct inspections semi-annually and after heavy
  rains or rapid  melting of snow.
Guidance 2: Inspect the interior of the foundation.
• Inspect the foundation for changes in existing
  cracks and for new cracks that might indicate water
  problems.
• Check the condition and operation of the sump
  crock, drains and pump.
• Look for signs of seepage or wicking (e.g., water
  stains, damp materials, efflorescence, peeling
  paint or mold growth) on foundation materials and
  interior finishes.
• Check for musty odors.
• Look for swollen, warped or  moldy wooden
  materials.
• Determine the temperature and relative humidity.
  Record the date, time and operation of mechanical
  systems,  the temperature and the relative humidity.
• Look for stained carpet, sheet or vinyl composition
  tile (VCT) floors with blisters and for bubbles
  indicating adhesive failures  as well as adhesives
  oozing from joints between tile.
• Look for condensation on pipes, tanks, toilets,
  pumps, ducts, walls and floors.


Verification of Foundation Maintenance

• Document inspections and responses using a
  checklist and work order system.

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 Wall  Maintenance
                                                                                 www.epa.gov/iaq/moisture
Issue
Failure to properly inspect and maintain interior
and exterior walls can result in moisture problems
going unnoticed or unrepaired. Unnoticed damage to
walls can lead to a need to repair multiple building
components at high cost and can create health risks
associated with mold growth in the interior of walls.

Goals

Wall Maintenance Goal  1: Create and operate
verification and inspection systems to detect potential
moisture problems before harm is done.

Wall Maintenance Goal  2: Effectively maintain walls
to prevent moisture  problems, as intended by the
design.

Guidance

Wall Maintenance Goal  1: Create and operate
verification and inspection systems to detect potential
moisture problems before harm is done.

Guidance 1: Develop inspection checklists and
record-keeping systems.
• Develop a wall assembly manual and logbook.
  Include the type of wall, contractor information,
  maintenance procedures, a  record of inspections
  and related items.
• Develop a wall assembly inspection checklist.
  Use it as a guide for evaluating masonry units,
  flashings and counter flashings, caps and drainage
  assemblies.
• Develop elevation drawings  to map and locate
  problems found during the inspections.
• Develop and keep inspection and repair records
  for all exterior walls,  including before and after
  pictures to document results of  maintenance and
  repair activities.

Wall Maintenance Goal  2: Effectively maintain walls
to prevent moisture  problems, as intended by the
design.
Figure 4-1  Interior Wall Showing Water Damage and
Mold
Guidance 1: Conduct inspections, record the results
and make necessary repairs.
• Inspect walls periodically and after heavy winds and
  rains. Conducting inspections during each season is
  recommended.
• Check interior walls and ceilings for signs  of water
  damage or staining (See Figure 4-1).
• Inspect exterior walls and roof overhangs:
  • Look for signs of moisture, cracking or
    movement.
  • Look for cracked, loose or spalled units  on brick
    masonry walls.
  • Inspect joints for deteriorated mortar.
  • Look for mold or algae growth.
  • Be aware that ivy growing on brick walls can
    penetrate voids in mortar and may lead  to
    moisture penetration.
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  • Open weep holes by probing with a wood dowel or   • Identify and repair problems before they cause
    stiff wire. NOTE: Care must be taken to prevent       water damage to walls.
    damaging flashing when cleaning weeps.            . |ncorporate the resu|ts of each inspection into the
• Inspect caulking and sealants at junctions of the         user's manual and logbook.
  brickwork and other materials such as windows,
  doors and expansion joints.                          Verification of Wall Maintenance	
• Inspect flashings and counter flashings. Look for
  loose flashing or missing fasteners, open ends or       Incorporate completed inspection forms and
  lap joints, unsealed corners,  and rusted or corroded    completed checklists into the user's manual and
  metal.                                             logbook.
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                                                                                www.epa.gov/iaq/moisture
  Roof and Ceiling Assembly  Maintenance
ISSUE
Roof and ceiling assemblies can deteriorate due to
normal wear, severe weather, building movement,
and improper design, construction and maintenance.
Failure to correct roof and ceiling problems quickly
can cause additional damage to the building envelope
and the interior of the building. Uncorrected roof
and ceiling problems can also cause loss of occupant
productivity, damage to building contents and failure
of structural integrity.




Roof Maintenance Goal 1: Facility maintenance
systems and preventive maintenance plans effectively
address moisture control issues for roof and ceiling
assemblies.

Roof Maintenance Goal 2: Moisture does not
penetrate roof and ceiling assemblies or collect in
exterior elements, except as intended by the design.




Roof Maintenance Goal 1: Facility maintenance
systems and preventive maintenance plans effectively
address moisture control issues for roof and ceiling
assemblies.

Guidance 1: Read, understand and comply with the
manufacturers' or installation contractors' warranty
terms and conditions.

Guidance 2: Develop tools for routine inspection and
maintenance.
• Develop a roof and ceiling assembly inspection
  checklist (See Appendix B for a sample). Use it as
  a guide for observing and  evaluating the roof and its
  systems, equipment mounted on the roof, drainage
  problems and traffic patterns.
• Develop a roof and ceiling assembly user's manual
  and logbook. Include such information as:
  • The type of roof, gutter, external downspout
    system and internal drain and cover.
  • Installation contractor information.
  • Roof, ceiling assembly and drainage system
    manufacturers.
  • Warranty information.
  • Record of inspections.
• Prepare a map showing all roof and ceiling
  assembly features such as scuttles, HVAC
  equipment, drains, gutters, downspouts, scuppers,
  vents and roof angle changes.  Use this map
  to locate items of  interest observed during the
  inspection.  (See Appendix B for a sample map of a
  roof and ceiling assembly.)

Roof Maintenance Goal 2: Moisture does not
penetrate roof and ceiling assemblies or collect in
exterior elements, except as intended by the design.

Guidance 1: Inspect the roof and ceiling assemblies to
determine whether they are performing their intended
functions; to identify signs of weakness, deterioration
or hazards; and to identify needed repairs.

Frequency of  Inspection

• Inspect semi-annually or in accordance with
  manufacturer's requirements and as soon as
  possible after heavy winds or rains.
• Conduct special inspections after events such as
  construction on the roof or adjacent roofs, rooftop
  equipment  installation, fire or vandalism.


Prepare for Inspections

• Review, learn and  follow roof safety procedures.
• Review past inspection reports, construction
  documents  and past maintenance and repair reports
  before inspecting the roof.

Conduct Inspections

• Use ladders to inspect steep roofs. Ensure all
  ladders comply with,  and are maintained and
  used in accordance with, the Occupational
  Safety and  Health Administration (OSHA) 29


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  CFR Occupational Safety and Health Regulation
  requirements.
• Do not rest ladders against gutters. When on the
  roof, take care to step on the flat portions of the
  panels over structural  members and not on side-
  laps or standing seams.
• Inspect interior walls and ceilings for signs of water
  penetration (i.e., water damage or staining)  or
  structural distress. If possible, check the underside
  of the roof deck. Look for water or insect damage,
  deterioration of the deck, rusting, settling or other
  physical damage.  Inspect the interior surface
  of exterior walls and roof overhangs for signs of
  moisture, cracking or movement.
• Inspect exterior walls and roof overhangs for signs
  of moisture, cracking or  movement.  Inspect exterior
  grounds around buildings for signs of ponding,
  which may indicate blockage.
• Inspect the roof covering and edge for continuity.
  Look for deterioration, damaged or loose laps and
  seams, loose or missing  fasteners, rust or corrosion,
  physical damage to the roof covering, and the
  accumulation of debris and vegetation. Look for soft
  roof  insulation and cracked,  spalled or discolored
  walls.
• Inspect for moisture infiltration. Pay attention
  to areas where walls or parapets intersect roofs,
  around rooftop  HVAC units, and around skylights  or
  other roof  penetrations. Check for missing or broken
  weather seals on equipment housings and cracked
  or missing caulking.
• Inspect flashings at roof-wall intersections and at
  curbs.  Look for loose flashing or missing fasteners,
  open ends or lap joints,  unsealed corners and
  rusted  or corroded metal. If caulk or roofing tar
  has been used as a temporary repair, inspect for
  cracks. Also inspect flashings around curbs, access
  hatches and rooftop equipment. Where deflection is
  required, make sure that roof panels and flashings
  move independently.
• Inspect hips, ridges and valleys. Look for loose or
  missing fasteners, open  ends or open lap joints,
  damage from foot traffic and corroded metal. In
  valleys, check to make sure the roof covering is
  secured at the valley edges and that there are no
  obstructions blocking water flow.
• Inspect the drainage system. Check gutters  and
  downspouts for loose or  missing fasteners, loose
  joints,  corrosion and debris.  Make sure sealants and
  solder are  in good condition. Check downspouts,
  interior roof drains, scuppers and outlets to  ensure
  they are not blocked. If possible, shine a flashlight
  down each downspout and leader to check for
  blockage.  If  blockage is suspected  in a downspout
  running through the interior of the  building, snake
  out the downspout or use a mechanical auger.
  Do not use water to try to flush out an interior
  downspout suspected of being blocked. If a roof
  drain is blocked by ice, do not try to open it by
  chipping or breaking the ice. Ensure that all joints
  are properly  sealed. Inspect masonry weep holes for
  signs of dripping.
• Look for ponding or standing water on the roof. Pay
  particular  attention to areas around scuttles, curbs,
  skylights and other features that may impede roof
  drainage. Another indication of a failed drainage
  system is accumulated debris on the roof. Remove
  all litter and debris from the roof surface. Standing
  water can  damage the gravel and the granule
  or liquid coatings on roofs. Once these coatings
  are damaged, sunlight can degrade the roofing
  membrane. Look in the gutters for  mineral granules
  from shingles, which may indicate  that the shingles
  are worn. A small penetration can allow standing
  water to seep under the membrane. Deflection
  may indicate structural problems that must be
  addressed.
• Include non-destructive tests such  as infrared
  thermography or other appropriate tests if moisture
  intrusion is suspected.
• Record and report inspection findings.
• Report immediately any unsafe working conditions
  or potential system failures.

Special Considerations for Membrane Roofs

• Pay particular attention to areas between roof
  trusses and beams, which are likely spots for roof
  deflection.
• Inspect the roof membrane for moisture  intrusion.
  Pay particular attention to the joints between two
  sheets of membrane and to changes in the angle of
  the roof:
  • Built-up bituminous  membrane roofs:  Look for
    blisters caused by the expansion of air or water
    vapor trapped beneath. Also look for cracks in
    the membrane, splits, ridges and lifting of the
    membrane at the seams.
  • Elastomeric membranes: Look for open seams,
    shrinkage  and backed-out fasteners. Inspect the
    roof for damage after windstorms. Pay particular
    attention to the membrane surface, roof edge
    metal, flashings, gutters and downspouts.
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  • Ballasted roof systems: Look for missing or
    displaced ballast and insulation boards beneath
    the roof membrane.
  • Adhered roof systems: Look for loose areas of
    the membrane, displaced insulation boards
    and tented  insulation fasteners and  plates. On
    mechanically attached roof systems, look for cuts
    in the membrane, displaced  insulation boards
    and tented  roof fasteners and plates. Inspect for
    loose flashing. Also inspect rooftop HVAC units
    for loose or missing sheet metal components.


Special Considerations for Asphalt Shingle Roofs

Pay particular attention to the tops of the vertical
slots between tabs. This area is usually the last to dry.
Moss and lichen growth on asphalt roofs  keeps the
roofing materials damp, so use a water hose and
nozzle to remove moss and lichen. Spray from the
                            www.epa.gov/iaq/moisture
roof facing down the slope to avoid spraying water up
under the shingles.

Guidance 2: Repair as needed to meet or exceed
warranty requirements.

Develop a maintenance work plan to correct deficient
conditions in a timely  manner.

Verification  of Roof and Ceiling Assembly
Maintenance

• Incorporate the completed checklist and map into
  the user's manual and logbook upon completion of
  each inspection.
• Keep and  maintain records of all inspections,
  including the checklist. Include photographs and
  test reports so that changes in roof conditions can
  be verified.


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www.epa.gov/iaq/moisture
  Plumbing System Operation  and Maintenance
Issue
Improperly maintained plumbing systems can cause
flooding or condensation build-up. Since plumbing
is often  located in areas that are not often viewed by
occupants, poor maintenance can  lead to unnoticed
mold growth that can damage the building and its
contents, as well  as pose health risks to occupants.

Goals

Plumbing Maintenance Goal 1: Plumbing systems
are inspected and maintained to prevent flooding or
condensation.

Guidance

Plumbing Maintenance Goal 1: Plumbing systems
are inspected and maintained to prevent flooding or
condensation.

Guidance 1: Develop a plumbing system inspection
and maintenance plan. The plan should include:
• The name, address and telephone number of the
  person or persons responsible for inspection and
  maintenance of the plumbing systems.
• Specific preventive and corrective maintenance
  requirements, which can  be in the form  of
  checklists. Inspection checklists should be
  developed for:
  • Water supply and distribution piping,  pumps and
    valves.
  • Water usage equipment such as sinks and
    drinking fountains.
  • Hot water heaters and storage tanks.
  • Fire sprinkler systems,  which should  be
    inspected in accordance with  National Fire
    Protection Association  (NFPA) standards or local
    code requirements.
  • Building drainage systems such as floor drains,
    sumps and pumps.
  • Other facility plumbing systems and components
    such as pipe insulation.
• A schedule of regular inspections and routine
  maintenance tasks.
• Detailed logs of all preventive and corrective
  maintenance tasks, including all maintenance-
  related work orders.
• Necessary maintenance equipment, tools and
  supplies.
• Emergency response actions.
• Procedures and equipment necessary to protect the
  safety and health of inspectors and maintenance
  workers.
• System component manufacturers' literature and
  warranties.
• As-built construction plans.
• Training of maintenance personnel.

Guidance 2: Inspect plumbing systems and
components. Make sure:
• Inspections are performed according to the
  timetable in the plumbing system inspection and
  maintenance plan.
• Inspection results are logged into the plumbing
  system inspection and maintenance plan.
• Work orders are prepared for  maintenance
  requirements found during the inspections.

Guidance 3: Maintain plumbing systems and
components by performing regularly scheduled
preventive maintenance and unscheduled
maintenance to correct problems discovered during
inspections. Regular maintenance will save money in
the long run.

Verification of Plumbing System Operation and
Maintenance

• Completed inspection checklists.
• Completed maintenance checklists.
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                                                                                www.epa.gov/iaq/moisture
  HVAC  System  Operation  and Maintenance
Issue
Failure to adequately maintain HVAC systems can
lead to moisture problems including loss of humidity
control, condensation and overflowing drain pans.
Regularly scheduled inspections and maintenance
can prevent unexpected equipment failure and  reduce
the equipment's life-cycle cost. Properly maintaining
HVAC systems helps to ensure occupant comfort and
healthy indoor air quality.

Goals

HVAC Operations and Maintenance Goal 1: Facility
maintenance management systems and preventive
maintenance plans effectively address moisture
control in HVAC systems.

HVAC Operations and Maintenance Goal 2: HVAC
systems are maintained as intended  by manufacturer's
specifications and system design to effectively control
moisture.

Guidance

HVAC Operations and Maintenance Goal 1: Facility
maintenance management systems and preventive
maintenance plans effectively address moisture
control in HVAC systems.

Guidance 1: Develop and implement facility
maintenance management systems and HVAC system
preventive maintenance (PM) plans, or review and
revise existing systems and plans, to control moisture
effectively. Maintenance management systems  and
PM plans for HVAC systems should:
• Incorporate moisture control into the functional
  objectives that guide the maintenance program
  (e.g., as a stand-alone objective, as part of an
  indoor air quality objective or as part of a reliability
  or long-term cost-minimization objective).
• Develop a performance objective for moisture
  control (e.g., number of unanticipated leaks,  dollars
  spent on  leak repair, number of hours when indoor
  relative humidity falls within the specified design
  range, etc.) and track performance to determine
  whether that objective is being met.
• Maintain records of all HVAC system installations,
  inspections and maintenance, along with warranty
  information and requirements.
• Incorporate best practices for moisture control in
  the inspection and maintenance of HVAC systems.
  Particular attention should be paid to coils and
  drain pans, humidifiers, cooling towers, the
  introduction of humidity-laden air and the potential
  for condensation. (See HVAC Operations and
  Maintenance Goal 2 for more detailed guidance  on
  conducting HVAC maintenance inspections.)
• Ensure that planners and schedulers assign
  inspectors who are knowledgeable about the HVAC
  and plumbing systems being inspected.
• Schedule regular inspections at least semi-annually
  or in accordance with manufacturer's requirements.
  Additional inspections should be scheduled as soon
  as possible after heavy winds or rains or after any
  construction or installations that could affect the
  integrity of these systems, especially their outdoor
  components.
• When developing work orders for moisture-related
  maintenance tasks, include best practices and
  checklists for detailed inspections and maintenance
  tasks (See HVAC Operations and Maintenance Goal
  2) in the scope of work and instructions.
• Incorporate best practices and checklists (See
  HVAC Operations and Maintenance Goal 2)  into
  training programs for inspectors and maintenance
  personnel who deal with these drainage systems.
• Give priority to moisture-control issues in preventive
  maintenance, major maintenance and repair, and
  capital renewal planning and budgeting.

HVAC Operations and Maintenance Goal 2: HVAC
systems are maintained as intended by the
manufacturer's specifications and the system design
in order to effectively control moisture.


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Guidance 1: Maintain HVAC system components in
accordance with the manufacturer's requirements
and the moisture control recommendations in
this guidance. At a minimum, the following HVAC
components should be inspected as part of a PM
program:


Thermostats

• Thermostats should be checked in the fall and
  spring, shortly after switching to or from daylight
  saving time, or whenever complaints about thermal
  comfort are received.

Checking Thermostat Operation and Calibration

• If the thermostat is programmable, make sure
  the time is set correctly and the thermostat is
  programmed for the hours when the building is
  occupied.
• Place a calibrated thermometer next to the
  thermostat. Place a paper towel or other material
  between the thermometer and the wall to make
  sure the wall temperature is not influencing the
  thermometer reading.
• Allow the thermometer to stabilize. How long this
  takes will depend on the thermometer used.
• Compare the thermostat and thermometer readings.
  If the thermostat differs by more than 1°F, there is a
  problem and you should do the following:
  • Remove the faceplate and check whether the
    thermostat is dirty. Carefully brush or blow away
    any accumulated dust.
  • If contact points are accessible, clean them
    with a soft cloth. Do not use sandpaper or other
    abrasive materials.
  • If the thermostat has a mercury switch, check
    that it is level. Be very careful not to break the
    vial that contains the mercury.
  • Check behind the thermostat to  make sure the
    hole for the wires is caulked to prevent air within
    the wall from influencing the thermostat reading.
  • Allow temperatures to stabilize and compare the
    thermostat and thermometer readings again. If
    they still differ by more than 1°F, replace the
    thermostat.
Control Sequence

• Make sure the clocks on all systems read the
  correct time and date (if applicable); adjust if
  necessary.
• Check that equipment is turned off or energized
  according to the control sequence. (Observe the
  actual operation of fans, dampers and valves as well
  as the operation of the control unit.)

Outdoor Air Intakes

• Inspect the area around intakes for potential
  contaminant sources such as dumpsters, garbage
  cans, decaying organic matter and automobile
  idling or parking areas.  If there are contaminant
  sources near the intakes, move them if possible.
  If contaminant sources are not mobile, other steps
  may be required to prevent the intake of airborne
  contaminants. These steps may include relocating
  intakes or instituting policy changes such as
  prohibiting vehicle idling.
• Inspect the outdoor air intake louver and the debris
  screen  behind it. Check for signs of rain leaks and
  clogged screens. If rainwater intrudes into the
  outdoor air intake, modify as needed  to prevent
  entry. Remove grass  clippings, leaves, dust and
  other materials that obstruct the air intake. Take
  care when doing this during the warmer months
  because bees, wasps or other stinging insects
  may have nested in the intake. NOTE: Do not use
  a pesticide if  insects are found in the outdoor air
  intake.
• If outdoor air  intakes are close to ground level,
  ensure  that all landscape plantings are at least 5
  feet from the  intake. Require lawns to be mowed in
  a manner that directs the cut grass away from the
  building and the intakes.

Outdoor Air Dampers

• Determine the outdoor air damper control sequence,
  then change the parameters to force the dampers to
  open and close. Do not rely on observing linkages;
  watch the outdoor air dampers for movement. Make
  necessary repairs to  ensure dampers open and  close
  in  accordance with the control sequence.
• Measure outdoor air  volumes on a regularly
  scheduled basis and whenever indoor air quality
  problems arise. Either purchase equipment such
  as balometers, anemometers, manometers and
  pitot tubes to  take these measurements, or hire a
  qualified  contractor.
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Cooling Coils, Drain Pans, and Condensate Lines

• Inspect coils, pans and condensate lines regularly
  for cleanliness and to ensure the drain is operating
  correctly. Clean or repair faulty drains as necessary.
• Ensure that all traps have water in them. During
  times of the year when the HVAC system is not
  used, or when condensate formation is low, the trap
  can dry out, allowing sewer gases or other gases in
  the drainage system to be drawn into the HVAC unit
  and distributed through the building. Fill empty
  drain traps with water.
• Closely inspect the ducts downstream from
  the cooling coil for mold growth or signs of
  condensation being blown off the coil. If mold is
  found growing on hard-surface  ductwork (e.g., sheet
  metal) or closed-cell insulation, have the ductwork
  evaluated by a mold remediation specialist or a
  qualified duct cleaner. If mold  is found  growing on
  internal porous duct insulation, remove and replace
  the insulation because it cannot be effectively
  cleaned.
Evaporative Cooling Equipment (Common in Dry
Climates)

• Inspect the evaporative pad media regularly for
  cleanliness,  and even wetting, across the full face
  of the pad. Replace clogged media to ensure that
  supply air is not constricted and forced into high-
  velocity flow, which  could pull water off the media
  and into the air stream and ductwork downstream.
  Similarly, make sure the water flow is even across
  the full face of the pad (for effective cooling) and
  not excessively  high in any one spot, which could
  also result in water droplets being pulled off the
  media and into  the air stream.
• Ensure the overflow drain is operating correctly.
  Clean out or repair the drain  lines as necessary
  to ensure that water does not collect in the sump
  and overflow the edge of the  pan. (Overflows can
  otherwise leak into ductwork or into the building
  itself.)
• Ensure that  the media is not contacting standing
  water in the sump when the unit is not operating.
  The sump overflow adjustment must be low enough
  to prevent water from wicking back up into the
  media and supporting microbial growth.
• Check the controls to ensure that the evaporative
  cooler does not operate when it is raining outdoors.
  Otherwise, the unit could overload the incoming
  air with humidity at a time when  little evaporative
                             www.epa.gov/iaq/moisture
  cooling needs to be accomplished. Needlessly
  loading the indoor air with extra humidity can
  lead to excess moisture accumulation, even in dry
  climates.
• Closely inspect the ducts downstream from the
  evaporative cooler coil for mold growth or signs
  of moisture being blown off the media. If mold is
  found growing on hard-surface ductwork (e.g., sheet
  metal) or closed-cell insulation, have the ductwork
  evaluated by a mold remediation specialist or a
  qualified duct cleaner. If  mold is found growing on
  internal  porous duct insulation, remove and replace
  the insulation because it  cannot be effectively
  cleaned.  Before the equipment is placed back in
  operation, locate and correct the problem that led
  to the carryover of water droplets which supported
  the mold growth.

Air  Filters

• Do not rely solely on pressure drop warning
  equipment to determine the need to replace
  filters. Clogged filters can be sucked out of their
  frames and air may bypass the filter, resulting
  in no noticeable  pressure drop. Visually inspect
  and replace air filters on a regular schedule. Turn
  unit fans off when changing filters to prevent
  contamination of the air.  Be aware that some filters
  may need more frequent  replacement than others
  because different areas of a facility may  have
  different airborne particle burdens.
• Record the date of the filter change in the
  maintenance manual and write the date  of the
  change on the filter, if possible.

Ducts and Supply Diffusers

• Inspect ducts regularly, typically once a year or
  whenever modifications have been made to the
  ducts or the areas they serve.
• Information about the potential benefits  and
  possible problems of air duct cleaning is limited.
  The North American Air Duct Cleaners Association
  (NADCA) recommends duct cleaning if there is
  a significant build-up of particles, if the  duct is
  contaminated with mold spores and trace mold
  growth, or if there is obvious mold growth. If  mold
  is growing in  ducts lined with porous insulation,
  the NADCA guidance recommends removing the
  insulation. When cleaning ductwork, follow the
  2006 NADCA guidance Assessment Cleaning and
  Restoration of HVAC Systems.
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• Inspect ducts for physical damage.  Look for
  crushed or disconnected  ducts. Reconnect, repair
  or replace as necessary.
• Inspect all accessible duct seams and joints for
  leaks and seal all leaks with appropriate  materials.
  Seal duct leaks with mastic, metal-backed tape
  or aerosol sealant. Duct tape should not be used
  because it dries out quickly  and fails to hold and
  because it cannot withstand high temperatures. All
  sealing materials must  comply with Underwriter's
  Laboratory Standard UL 181A; check the labels.
• Inspect supply diffusers and the ceiling around
  diffusers for dirt and dust that can indicate dirty
  ducts or missing, inefficient or bypassed filters.
  Note that dirt and dust patterns on  supply diffusers
  or ceilings do not necessarily mean  the HVAC
  system is the source of the dirt. The vortexes
  created as air exits the  diffuser can deposit dust
  from the ambient air onto surfaces.
• Send dirt and dust samples  to an environmental
  laboratory for microscopic examination to determine
  whether the particles look like soot, lint,  mold, sand
  or something else.
• Look for mold growth on diffusers supplying cooled
  air to the space. Condensation caused by cooling
  the diffuser below the dew point can support mold
  growth. Clean as needed  and determine what
  actions are  necessary to prevent condensation.

Return Air Plenums

• Return air plenums are spaces that  do not have
  ducts and typically are  found above T-bar ceilings—
  suspended ceilings—and below the roof or floor
  deck above. Dust, mold and other contaminants
  within the space can migrate back to the  HVAC
  unit and be distributed to the occupied areas of the
  building.
• Periodically inspect buildings that have return
  air plenums for water-stained ceiling tiles, which
  may indicate mold growth. If mold growth is found
  or suspected, consult a qualified professional
  to determine the extent of the problem and
  remediation requirements.

Guidance 2: Monitor temperature and humidity while
commissioning or recommissioning the HVAC system
to ensure humidity control is functioning effectively.
• Penetrations in the return plenum  may draw outdoor
  air into the system. If it is hot and humid outside
  this  can cause condensation on chilled surfaces,
  in internal building cavities, or in walls or ceilings.
  Monitoring temperature and relative humidity in
  the building, supply air, return air, and outdoor air
  during HVAC commissioning or recommissioning
  allows tracking of humidity sources. The absolute
  humidity  or humidity ratio can be calculated from
  these data and mass balance can be made  to
  determine whether there  is a source of humidity on
  the return side of the system.
• The  dehumidification performance of the building
  commissioning or recommissioning should  be
  tested when the building  is occupied.

Verification of  HVAC System Operation Maintenance

Set inspections and routine maintenance efforts in
accordance  with  equipment warranty requirements.
Appendix E  contains a sample HVAC inspection
checklist. Inspection records should  be kept to track
the results and any subsequent repairs needed.
REFERENCES
American Society for Testing and Materials. 2003. Standard test
    method for determining air leakage rate by fan pressurization.
    E779-03. Pennsylvania. American Society for Testing and
    Materials.

American Society for Testing and Materials. 1996. Standard
    test methods for determining airtightness of buildings using
    an orifice blower door. E1827-96. Pennsylvania. American
    Society for Testing and Materials.

American Society of Heating, Refrigerating and Air-Conditioning
    Engineers. 2004. ASHRAE Handbook of Fundamentals.
    Ventilation for Acceptable Indoor Air Quality. Standard 62.1.
    Atlanta.,GA: American Society of Heating, Refrigerating and
    Air-Conditioning Engineers.
    (The ASHRAE ventilation standard provides information
    needed to determine ventilation rates for differing
    occupancies plus a number of design, operation and
    maintenance requirements to ensure proper performance
    of ventilation equipment. Section 6.2.8 specifically deals
    with exhaust ventilation. Standard 62.1 applies to many
    situations.)

International Code Council. 2003. ICC International Plumbing
    Code. Sections 312.2 to 312.5. Washington, DC:
    International Code Council.
    (Sections 312.2 to 312.5 of these codes specify a gravity
    test of the drain and vent side of plumbing systems.)
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Mold Litigation Task Force of the Associated General Contractors
    of America, Inc. 2003. Managing the risk of mold in the
    construction of buildings. CONSTRUCTOR, http://www.agc.
    org/galleries/conrm/may03  mold.pdf. Accessed November 6,
    2013.

North America Air Duct Cleaners Association (NADCA). 2006.
    ACR 2006 Assessment, Cleaning and Restoration of HVAC
    Systems, National Air Duct Cleaners Association, Washington,
    DC. http://www.nadca.com/sites/default/files/userfiles/
    ACR%202006.pdf. Accessed November 6, 2013.

United States Environmental Protection Agency. 2005.
    Authorization Status for EPA's Stormwater Construction and
    Industrial Programs: States, Indian Country and Territories
    Where EPA's Construction General Permit (CGP) and Multi-
    Sector General Permit (MSGP) Apply. Washington, DC:
    United States Environmental Protection Agency. http://cfpub.
    epa.gov/npdes/stormwater/authorizationstatus.cfm. Accessed
    November 6, 2013.
    (This website outlines the relevant authority—U.S.
    EPA, state, or local government—for compliance with
                                  www.epa.gov/iaq/moisture

    National Pollutant Discharge Elimination System [NPDES]
    requirements for construction in a given state.)

United States Environmental Protection Agency. 2006.
    Construction Site Stormwater Runoff Control. Washington,
    DC: United States Environmental Protection Agency, http://
    cfpub.epa.gov/npdes/stormwater/menuofbmps/index.
    cfm?action=min measure&min measure id=4.  Accessed
    November 6, 2013.
    (This website outlines best management practices [BMPs] for
    controlling storm water runoff at construction sites.)

United States Environmental Protection Agency. 2006.
    Stormwater Discharges from Construction Activities:
    Overview. Washington, DC. http://cfpub.epa.gov/npdes/
    stormwater/const.cfm. Accessed November 6, 2013.
    (This website outlines the federal requirements  for complying
    with National Pollutant Discharge Elimination System
    [NPDES] requirements for construction.)
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 Appendix A - The "Pen  Test"
                                                                                  www.epa.gov/iaq/moisture
PURPOSE
By tracing the continuity of all the materials for
each control function, the  "pen test" checks the
completeness of:
    •   Rainwater protection.
    •   The insulation layer.
    •   The air barrier.

To verify continuity, create sections in which each
of these moisture-control elements is traced in a
different color to show that the design specifically
accounts for them. Contractors can then easily check
the sections against their experience with materials,
trades and sequencing. The sections will also provide
maintenance workers in buildings and grounds with
information useful in ordinary maintenance work or in
the event of a problem during building use.




Rainwater Protection Continuity
To demonstrate complete rainwater protection using
the section drawing, place a pen  on  a material that
forms a capillary break between the  rain-control
materials that get wet and the inner portion of the
enclosure that must stay dry. Without lifting the
pen off the paper, trace from the center of the roof
around the walls,  windows, and doors and along the
foundation to the  center of the foundation floor.

Figure A-l serves as documentation of rainwater
protection continuity. The following describes the
traceable capillary break in a sample section. Starting
at the center of the roof:
• The roofing membrane separates wet  materials from
  the inner dry  materials.
• Tracing to the edge of the roof, the roofing
  membrane flashes beneath  a metal coping, this in
  turn flashes to a metal fascia.
• The fascia forms a drip edge, channeling water
  away from the cladding.
• An air gap between the drip edge and the brick
  veneer forms a capillary break protecting the
  materials beneath the metal coping from rainwater
  wicking from below.
• An air gap and water-resistant barrier behind the
  brick veneer form a capillary break between the
  damp brick and the inner walls.
• The water-resistant barrier shingles over a head
  flashing, protecting the window from rainwater with
  a drip edge and air gap.
• The window frame, sash and glazing form a
  capillary break system that sits in  a pan sill flashing
  at the bottom of the rough opening.
• The pan sill  flashing forms a capillary break
  protecting the wall beneath from seepage through
  the window system.
• The pan sill  flashing shingles over the water-
  resistant barrier in the wall beneath.
• The water-resistant barrier shingles over a flashing
  that protects the bottom of the wall system where:
  • The foam  sill seal makes a capillary break
    between the foundation and  the bottom of the
    framed wall, connecting with:
      One inch of extruded styrene foam insulation
      making  a capillary break between the top of the
      foundation wall and the edge  of the floor slab.
  • Polyethylene film immediately beneath the slab
    forms a capillary break between the bottom of
    the slab and the fill below. NOTE: If the bed of
    fill beneath the slab consists of pebbles greater
    than 1A  inch in diameter and contains no fines,
    then it forms a capillary break between the soil
    and the slab.

Apply the same procedure to the  insulation layer
(Figure A-2)  and the air barrier (Figure A-3).
                                                   A-l

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Figure A-1 The Blue Line Traces the Elements of the Capillary Break in the Rainwater Control System for a Section
Through a Building
     Facia
     Drip edge and
     air gap

     Spray foam insulate
     I-beam

     Self-adhered membrane
     covers gypsum wall and
     seals to flashing

     Gypsum sheathing

     1"foam board

     Air gap

     Head flashing (flashes
     beneath self-adhered
     membrane)

     Pan sill flashing

     Self-adhered membrane

     Gypsum sheathing

     1"foam board

     Air gap

     Brick wall

     Flashing


     Foam insulation at
     down perimeter wall

     Concrete foundation wall
Coping

Steel "Z" angle

Tapered foam insulation

Roof membrane
Fluted steel deck
Self-adhered
membrane
Gypsum foam
boardings deck
6" light steel stud
w/R19 fiberglass
insulation
Roof drain

Window
6" light steel stud
w/R19 fiberglass
insulation
Polyethylene film
Concrete slab
Drainage layer
(coarse aggregate with no fines)
                                             A-:

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Figure A-2 The Red Line Traces Continuity of the Insulation Layer
                                                                            www.epa.gov/iaq/moisture
        Facia


        Drip edge and
        air gap

        Spray foam insulate
        I-beam

        Self-adhered membrane
        covers gypsum wall and
        seals to flashing

        Gypsum sheathing

        1" foam board

        Air gap

        Head flashing (flashes
        beneath  self-adhered
        membrane)

        Pan sill flashing

        Self-adhered membrane

        Gypsum sheathing

        1" foam board

        Air gap

        Brick wall
        Flashing
        Foam insulation at
        down perimeter wall

        Concrete foundation wall
Coping

Steel "Z" angle

Tapered foam insulation

Roof membrane
Fluted steel deck
Self-adhered
membrane
Gypsum foam
boardings deck
6" light steel stud
w/R19 fiberglass
insulation
Roof dram

Window
6" light steel stud
w/R19 fiberglass
insulation
Polyethylene film

Concrete slab
Drainage layer
(coarse aggregate with no fines)
                                               A-3

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Figure A-3 The Purple Line Traces the Air Barrier Components

                                                            Self-adhered
                                                            membrane
Facia


Drip edge and
air gap

Spray foam insulate
I-beam

Self-adhered membrane
covers gypsum wall and
seals to flashing

Gypsum sheathing

1" foam board

Air gap

Head flashing (flashes
beneath self-adhered
membrane)

Pan sill flashing

Self-adhered membrane

Gypsum sheathing

1* foam board

Air gap

Brick wall

Flashing
        Foam insulation at
        down perimeter wall

        Concrete foundation wall
                                                            Coping
                                                            Steel "Z" angle

                                                            Tapered foam insulation

                                                            Roof membrane
                                                            Gypsum foam
                                                            boardings deck

                                                            6" light steel stud
                                                            w/ R19 fiberglass
                                                            insulation

                                                            Roof drain    --^

                                                            Window

                                                            6" light steel stud
                                                            w/R19 fiberglass
                                                            insulation
                                                            Polyethylene film

                                                            Concrete slab
                                                    Drainage layer
                                                    (coarse aggregate with no fines)
                                               A-4

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Insulation Layer Continuity
To demonstrate a continuous layer of insulating
material around a section, place the pen tip on the
insulating layer in the center of the roof and trace
from one insulating material to the next around to
either the bottom of the foundation wall or the center
of the foundation floor.

Figure A-2 shows the continuity of thermal  insulation
in a sample section.
•  Beginning at the center of the roof, trace through
  foam insulation to the edge of the roof.
• One- or two-part polyurethane foam insulation
  applied in the field fills the top and bottom voids
  created by the fluted steel deck, providing both
   insulation and air barrier continuity.
• The field-applied foam connects to the top of the
  exterior foam insulation sheathing and the top
  channel of steel wall framing.
• The steel wall  framing is filled with cavity
   insulation, and the thermal bridge through the steel
   is insulated  by the exterior foam insulation.
• The rough opening between the exterior foam
  sheathing and the window jamb is insulated
  (and air sealed) with field-applied canned foam
   insulation.
                             www.epa.gov/iaq/moisture
• The window jamb, sash and glazing system provide
  insulation continuity to the rough opening at the
  bottom of the window,  which is insulated with
  canned foam.
• The exterior insulating  foam sheathing and
  cavity insulation carry the insulation layer to the
  foundation.
• Foam sill seal  provides thermal insulation between
  the bottom of the wall  and the concrete foundation,
  which carries thermal protection below grade to the
  bottom of the foundation wall.
• Vertical foam insulation applied to the interior of
  the foundation wall.

Air Barrier  Continuity
Continuity of the air barrier is demonstrated using
the same method used for rainwater control and the
insulation layer. Air barrier materials and the sealants
used to connect them are identified from the center of
the roof to the center of the  foundation floor.

In this case foam insulation  on the roof and walls,
windows and the concrete floor slab forms the basis
of the air barrier. The insulation components are
connected with sealants (e.g., field-applied canned
foam) and gasket-like materials (e.g., foam sill seal).
                                                   A-5

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www.epa.gov/iaq/moisture
 Appendix  B  - Roof  Inspection  Checklist
Parts of this inspection checklist are adapted from and used with the permission of the Government of The Northwest Territories Public Works and
Services Asset Management Division.

Before performing a roof inspection:
• Review past inspection reports, construction documents and maintenance and repair reports.
• Review,  learn and follow roof safety procedures.
• Use ladders to inspect steep roofs. Ensure all  ladders comply with, and are maintained and used in
  accordance with, the Occupational Safety and Health Administration (OSHA) requirements in Title 29 of the
  Code of  Federal Regulations (29 CFR).
Building:.

Address:
Roof Area or ID:
Inspected by:
Date:
Item
Interior
Exterior
ID - Number to be used to identify problem on roof sketch
G - Good, no action needed
F- Fair, monitor condition periodically, plan necessary repairs
P - Poor, immediate action needed
N/A - Not applicable
Interior Walls
Water stains
Water damage
Other wall problems
Ceilings
Water stains
Water damage
Other ceiling problems
Roof Deck
Water damage
Rusting
Settling/deflection
Deck deterioration
Other roof deck problems
Downspouts/Leaders
Missing pieces
Loose pieces
Evidence of blockage
Damaged joints
Split joints
Surface ponding
Other downspout/leader
problems
ID
1
2
3
ID
4
5
6
ID
7
8
9
10
11
ID
12
13
14
15
16
17
18
G



G



G





G







F



F



F





F







P



P



P





P







N/A



N/A



N/A





N/A







REMARKS



REMARKS



REMARKS





REMARKS







                                                  B-l

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Roof
Drainage
System
Roof Features
Exterior Walls
Water stains
Water damage
Other wall problems
General Conditions
General appearance
Traffic problems
Unauthorized access
Ponding
Debris
Physical damage
Deflection
Compressed insulation
Other roof problems
Gutters
Missing pieces
Loose pieces
Damaged pieces
Split joints
Corrosion
Loose fasteners
Debris in gutters
Slope to downspout
Other gutter problems
Internal Roof Drains
Missing drain screens
Blocked drain
Other drain problems
Scuppers
Blockage
Other scupper problems
Perimeter Edging/ Fascia/
Gravel Stop
Missing pieces
Loose pieces
Damaged pieces
Split joints
Corrosion
Loose fasteners
Other
Flashings
Missing pieces
Loose pieces
Damaged pieces
Split joints
Corrosion
Loose fasteners
Other flashing problems
ID
19
20
21
ID
22
23
24
25
26
27
28
29
30
ID
31
32
33
34
35
36
37
38
39
ID
40
41
42
ID
43
44
ID
45
46
47
48
49
50
51
ID
52
53
54
55
56
57
58
G



G









G









G



G


G







G







F



F









F









F



F


F







F







P



P









P









P



P


P







P







N/A



N/A









N/A









N/A



N/A


N/A







N/A







REMARKS



REMARKS









REMARKS









REMARKS



REMARKS


REMARKS







REMARKS








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Roof Covering
Roof-mounted Equipment
(HVAC, Signs, Skylights,
Etc.)
Flashings
Loose/missing access
panels
Condensate piped to drain
Contamination around
exhaust fans
Other equipment problems
Membrane Roofs
Bare spots in gravel or
displaced ballast
Cuts/punctures
Cracks/all igatoring
Blisters/fishmouths
Loose laps/seams
Ridging/wrinkling
Fastener back-out
Membrane shrinkage
Other
Shingled Roofs
Missing shingle(s)
Loose shingle(s)
Buckled shingle(s)
Curled shingle(s)
Missing tab(s)
Granular loss
Other shingle problems
Metal Roofs
Loose or damaged seams/
joint(s)
Loose panel(s)
Worn panel(s)
Damaged panel(s)
Loose fastener(s)
Finish condition
Other metal roof problems
ID
59
60
61
62
63
ID
64
65
66
67
68
69
70
71
72
ID
73
74
75
75
77
78
79
ID
80
81
82
83
84
85
86
G





G









G







G







F





F









F







F







P





P









P







P







N/A





N/A









N/A







N/A







REMARKS





REMARKS









REMARKS







REMARKS









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                                                                                  www.epa.gov/iaq/moisture
Use this graph paper to sketch the roof plan. Include north arrow and the location of problems found during the
inspection. Use the roof ID numbers on the checklist to identify specific problems.
                                                   B-4

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www.epa.gov/iaq/moisture
 Appendix C  - Testing Moisture  During  Construction
The moisture content of wood, wood products and
other porous materials is an important factor in
mold growth and other moisture-related problems. A
porous material susceptible to mold growth, such as
wood, oriented strand board (OSB), medium density
fiberboard (MDF) or untreated paper-faced gypsum
board, will experience mold growth if its moisture
content is too high. Damp porous materials that are
resistant to mold growth, such as concrete products
and treated lumber, may indirectly support mold
growth by wetting vulnerable materials that are in
contact with them.  For example, untreated paper-
faced gypsum board attached to damp lumber or
concrete may be the site of  mold growth until the
damp materials dry.

Wood and wood products that contain a great deal
of moisture should  not be used in construction until
their moisture content is below a certain percentage.
Unfortunately, research on this dynamic is mostly
confined to laboratory research  and anecdotal reports
from forensic cases. The California Builder's Guide
to Reducing Mold Risk suggests an upper threshold
of 19 percent moisture content for wooden materials.
To avoid problems with shrinking or expansion, wood
ideally should be installed at moisture content levels
as close as possible to the average moisture content
it will experience in service. The in-service moisture
content of exterior wood depends on the outdoor
relative  humidity and exposure  to rain and sun. The
in-service moisture  content  of interior wood depends
on the  indoor relative humidity, which in turn  is a
function of moisture sources, ventilation rates and
dehumidification. The in-service moisture content of
exterior and interior wood depends on the climate  in
which the building  is located and on the building's
design  and intended use. The U.S. Department of
Agriculture's Wood Handbook recommends average
moisture content of 15 percent or less, with maximum
readings of 19 percent or less,  to avoid dimensional
change  problems.

The moisture content of materials is usually expressed
as the percentage of the weight of water in the
material relative to  the weight of the dry material.
In laboratories,  moisture content can be calculated
by weighing the test sample while damp, drying
the sample using heat or desiccant salts, and then
reweighing the sample. Electronic meters with direct
reading scales or displays have been developed for
wooden materials. Their use on lumber is extensively
documented.  ASTM D 4444-92 (Reapproved 2003)
Standard Test Methods for Use and Calibration of
Hand-Held Moisture Meters describes several types of
moisture meters, their use on wooden materials, and
quality assurance/quality control (QA/QC) procedures.

Knowing the moisture content of porous building
materials other than wood or wood products, such as
gypsum board and concrete slabs or concrete masonry
units, is also  important. Some electronic moisture
meters have calibrated scales for materials other than
wood, for example concrete, brick and plaster. It has
become common practice in the building diagnostic
field  to test materials other than lumber using
electronic  meters and to report the results using the
scale for lumber. In this way, investigators report the
moisture content of gypsum board, MDF and OSB as
the wood moisture equivalent (WME). The California
Builder's Guide to Reducing Mold Risk suggests an
upper limit of 16 percent  WME for gypsum  board
before finishing or installing cabinets. This limit
translates  roughly to 0.9 percent moisture content by
weight for gypsum board.

The ability to  measure material moisture content
after construction is valuable for diagnosing
post-construction problems such as water leaks,
condensation  and mold growth. It is recommended
that  builders  and facility managers measure the
moisture content of materials during post construction
diagnosis and problem solving.

A second moisture dynamic, the emission rate of
water vapor from materials such as concrete floors,
can have a dramatic impact on flooring materials.
For example,  floor covering manufacturers specify
the maximum water vapor emission rate of concrete
over  which coverings  such as tile and carpet can
be installed. Installing a covering on concrete that
exceeds the maximum emission rate may cause the
covering to fail, promote mold growth and void the
                                                  c-i

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manufacturer's warranty. It is recommended that the
vapor emission rate of a floor be measured before
coverings are installed (even when the installation
occurs long after the building was constructed);
whenever lifting tiles, blistered sheet vinyl,  or other
signs of floor failure are found; or when unexplained
high indoor relative humidity in ground-contact
spaces is encountered.

ASTM E  1907-06a Standard Guide to Methods of
Evaluating Moisture Conditions of Concrete Floors
to Receive Resilient Floor Coverings identifies eight
methods of testing concrete slabs. The two  most
commonly used methods are:
• F 1869 Test Method for Measuring Moisture
  Vapor Emission Rate of Concrete Subfloor Using
  Anhydrous Calcium Chloride. This test is  conducted
  using commercially available test kits. It  is a
                           www.epa.gov/iaq/moisture
quantitative test that provides a measure of the
vapor, in pounds of water in a 1,000 square foot
area, emitted over a 24-hour period. The test
involves weighing a canister of calcium chloride
desiccant, placing the canister on the slab to
be tested, and covering the canister with an air-
tight plastic dome supplied with the kit. The test
typically is conducted for 60 to 72 hours. After
that time, the canister is reweighed and the vapor
emission rate is calculated. This test method is
accepted by most floor covering manufacturers.
F 2170 Test Method for Determining Relative
Humidity in Concrete Floor Slabs  Using in situ
Probes. This method measures the head space
relative humidity in a hole drilled  partway through
the concrete slab. It  is gaining popularity in the
field and has been used in Europe for many years.
                                                   C-2

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www.epa.gov/iaq/moisture
 Appendix  D  - Air Pressure Mapping
Air pressure mapping is used to determine whether
air is moving through a building in a manner that
contributes to condensation problems. Unplanned
airflow will cause problems if either:
• Air is moving from the warm side of an exterior wall,
  the ceiling, or the basement to the cool side.
• Cold air is blowing from an air conditioning diffuser
  into a space where humidity is high.

To generate an air pressure map of a building, use:
• Floor plans showing the layout of each floor and
  the location of air handlers, supply diffusers, return
  grilles, and exhaust grilles.
• A micromanometer and flexible plastic tubing to
  measure pressure differences between indoor air
  and outdoor air, rooms and corridors, room air and
  plenum air, and room air and building cavities.
• A smoke bottle to determine the direction of air
  flow.

As depicted  in Figure D-l, use a micromanometer
to measure the pressure difference across a closed
door. Note that the tubing is run from one port of the
micromanometer to the far side of the door, while
the other port (with no tubing) senses the pressure
in the room. The micromanometer reads the pressure
difference. The minus sign on the micromanometer
interface indicates that the room is under negative
pressure relative to the other side of the door.

Figure D-2 shows the pressure map of a building that
consists of a single room with an operating  100-cfm
exhaust fan. The room is depressurized 4 Pascals
by the exhaust fan. The exhaust fan is represented
by a box with an  X in it and an arrow showing the
direction of airflow out of the building. The  line with
an arrowhead on one end and a circle on the other
signifies that air  is being drawn into the building from
outside.

This procedure can be applied to more complex
buildings and airflows to document air pressure
differences between rooms, indoors and outdoors,
attics, basements, crawlspaces, utility chases and
wall and ceiling cavities. Figure D-3 illustrates a
pressure map of a more complex building when the air
handler is running, the exhaust fans in the bathrooms
are running, there is no wind, and all the interior and
exterior doors are closed.
                                                  D-l

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Figure D-1 Measuring Pressure Difference Using a Micromanometer
                                                                                        www.epa.gov/iaq/moisture
                                                                       \L
Figure D-2 Pressure Map of a Building Consisting of a Single Room
                            100cfm
                                                   Exhaust Fan
                                                                           4 pascals
                                                      D-2

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Figure D-3 Pressure Map of a More Complex Building
       e-
                     1.6 Pa  0     CD1.3P
                                                Exhaust Fan        Air handler
                                                     1.3 Pa
-e
                0.0 Pa
               0.0 Pa 0
               0.0 Pa
               2.3 Pa 0
               -e
                                   0.0 Pa
                                     R
                                  -9 1.6 Pa
                                        R
                                -8  1.6 Pa
                                                             -e
                        LEGEND:
                      R
                 Supply diffuser
                 Return grille
                                        D-3

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                                                                www.epa.gov/iaq/moisture
 Appendix E - HVAC  Inspection Checklist
Building:.
     Location:
            Date:
Equipment:




Other ID:
               Manufacturer:
File # :
Prepared by:

Parameter
Outdoor Air Intake
Bird screen
Air flow unobstructed
No close-by pollutant sources
Mixing Plenum
Clean
Coils and Condensate Pans:
Clean, no corrosion
No odors
No microbial growth
Pans draining, traps filled
Humidifiers
Clean
No standing water or overflow
No microbial growth or mineral
deposits
Controls
Set points
Functioning
Fans
Clean, no corrosion
No excess vibration
Belts
No excess noise or vibration
No leakage
Pressurization
Filters
General condition
Installed properly (no bypass)
No odors/visible pollution
Condition
OK





























Not OK






























Notes





























Priority
L, M, H





























                                        E-l

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www.epa.gov/iaq/moisture
 Appendix F - Site Drainage  Maintenance
Regular maintenance of site drainage systems
is necessary to ensure they perform effectively.
Failing to regularly maintain drainage systems
can lead to reduced performance or system
failure. To help provide proper maintenance, a site
drainage maintenance plan that describes specific
maintenance requirements and schedules should  be
developed and used by the persons responsible for
drainage maintenance.

The maintenance plan differs from the checklists
provided in this appendix. The plan encompasses  the
entire site drainage maintenance requirements, while
the checklists provide requirements for a specific
drainage feature.

Maintenance Plan Requirements

The following site drainage maintenance plan
requirements have been adapted from the New Jersey
Storm Water BMP Manual (NJDEP04). Plans should
include:
• The name, address and telephone number of
  the person or persons responsible for preventive
  and corrective maintenance of the site drainage
  systems.
• Specific preventive and corrective maintenance
  requirements. These requirements may be in the
  form of checklists.
• A schedule of regular inspections and tasks.
• Detailed logs of all preventive and corrective
  maintenance tasks, including all maintenance-
  related work orders.
• Necessary maintenance equipment, tools and
  supplies.
• Emergency action responses.
• Procedures and equipment required to protect the
  safety and health of inspectors and maintenance
  workers.
• Approved disposal and recycling sites and
  procedures for the sediment, debris and other
  materials removed from the drainage systems
  during maintenance.
• System component manufacturer's literature and
  warranties.
• As-built construction plans.

In addition, the  plan should address the training of
maintenance personnel in the operational theory of
site drainage and in maintenance  and health and
safety procedures.

Site Drainage Inspection and Maintenance
Recommendations
The following inspection and maintenance
recommendations and checklists should be
augmented by state or local code requirements as well
as best management practices learned by persons
maintaining the  site drainage system.
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Dry wells are to be inspected four times each year and after every storm that exceeds 0.5 inches of rainfall.
Whenever possible, dry wells are also to be inspected before a major storm. Inspection consists of measuring
infiltration rates and drain times by observing the water level in the test well. The actual  drain time of the well
should be compared with the time it would take to drain the maximum design storm runoff volume. If significant
increases in drain time are noted, or if the dry well fails to dry within the design drainage time, maintenance is
required.

Dry well maintenance involves removing debris, trash or sediment that may have washed into the well.  In
addition to the dry well, any roof gutters, sumps or traps connected to the dry well are to be inspected  and
cleaned or repaired as necessary.
Building:.

Address:
Dry Well ID/Location:
Inspected by:.
Date:
ITEM
Roof
Gutters,
Leaders,
Sumps
and Traps
Test Well
Inspection
ID - Number to be used to identify problem on site sketch
G - Good, no action needed
F - Fair, monitor condition periodically, plan necessary repairs
P - Poor, immediate action needed
N/A - Not applicable

Missing pieces
Loose pieces
Evidence of
blockage
Damaged joints
Split joints
Surface ponding
Cleaning required
Other problems
Water level
Obvious debris
ID
1
2
3
4
5
6
7
8
9
10
G










F










P










N/A










REMARKS










                                                    F-2

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                                                        F-3

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Vegetated swales are to be inspected four times each year and after every storm that exceeds 0.5 inches of
rainfall. If swale vegetation consists of fast-growing grasses, the swales are to be inspected weekly. Whenever
possible, swales are to be inspected before a major storm. Inspection consists of looking for debris, evidence of
clogging and observable vegetation growth.

Vegetated swale maintenance consists of removing debris and sediment, maintaining the vegetation and
ensuring the swale drains within 48 hours.
Building:.

Address:
Swale ID/Location:
Inspected by:
Date:
ID - Number to be used to identify problem on site sketch
G - Good, no action needed
F - Fair, monitor condition periodically, plan necessary repairs
P - Poor, immediate action needed
N/A - Not applicable

Pea gravel diaphragm cleanliness
Grass or other vegetation
requires mowing
Trash/debris in inflow forebay
Erosion problems
Vegetation requires replacement
Swale does not drain within 48
hours - requires rototilling or
cultivating
Bottom sediment built up to 25
percent of original design volume
- requires sediment removal
Other problems
ID
1
2

3
4
5
6


7


8
G













F













P













N/A













REMARKS













                                                    F-4

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Dry extension ponds are to be inspected twice each year and after every storm that exceeds 0.5 inches of
rainfall. If side-slope vegetation consists of fast-growing grasses, the ponds are to be inspected weekly.
Whenever possible, ponds are to be inspected before a major storm.  Inspection consists of looking for debris,
sediment build-up, erosion and observable vegetation growth.

Pond maintenance consists of removing debris and sediment, repairing erosion, managing pesticides and
nutrients and maintaining the vegetation.
Building:.

Address:
Pond ID/Location:
Inspected by:
Date:
ID - Number to be used to identify problem on site sketch
G - Good, no action needed
F - Fair, monitor condition periodically, plan necessary repairs
P - Poor, immediate action needed
N/A - Not applicable

Erosion on pond banks
or bottom
Damaged embankment
Sediment accumulation
in the facility or forebay
Side slopes need
mowing
Pesticide and nutrient
management required
Ground cover requires
attention
Bottom sediment built
up to 25 percent of
original design volume
- requires sediment
removal
ID
1
2
3
4
5
6
7
G







F







P







N/A







REMARKS







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Wet ponds are to be inspected monthly and after every storm that exceeds 0.5 inches of rainfall. Whenever
possible, ponds are to be inspected before a major storm. If side-slope vegetation consists of fast-growing
grasses, wet ponds are to be inspected weekly. Inspection consists of looking for invasive species, debris, signs
of damage or erosion,  sediment accumulation and the need for managing or harvesting wetland plants.

Pond  maintenance consists of removing invasive species, debris, and sediment; repairing erosion; and managing
the vegetation.
Building:.

Address:
Pond ID/Location:
Inspected by:
Date:
ID - Number to be used to identify problem on site sketch
G - Good, no action needed
F - Fair, monitor condition periodically, plan necessary repairs
P - Poor, immediate action needed
N/A - Not applicable

Invasive species
Erosion
Sediment build-up in pond
or forebay
Debris
Wetland plant management
required
ID
1
2
3

4
5

G







F







P







N/A







REMARKS








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                                                        F-S

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Pervious pavement areas are to be inspected weekly and after every storm that exceeds 0.5 inches of rainfall.
Whenever possible,  pervious pavement areas are to be inspected before a major storm. Inspection consists
of looking for debris, sediment build-up, proper drainage after a storm, surface deterioration or spalling and
observable vegetation growth.

Pervious pavement maintenance consists of removing debris and sediment and maintaining the vegetation.
Building:.

Address:
Pavement ID/Location:
Inspected by:.
Date:
ID - Number to be used to identify problem on site sketch
G - Good, no action needed
F - Fair, monitor condition periodically, plan necessary repairs
P - Poor, immediate action needed
N/A - Not applicable

Area requires
cleaning
Improper draining
Sediment build-up
Upland area
requires mowing or
reseeding
Surface
deterioration or
spalling
ID
1

2
3
4


5


G










F










P










N/A










REMARKS










                                                   F-10

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                                                       F-ll

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Areas paved with porous modular pavers are to be inspected weekly and after every storm that exceeds 0.5
inches of rainfall. Whenever possible, areas are to be inspected before a major storm. Inspection consists
of looking for debris, sediment build-up, proper drainage after a storm, surface deterioration or spalling and
observable vegetation growth.

Pervious pavement maintenance consists of removing debris and sediment and maintaining the vegetation.
Building:.

Address:
Pavement ID/Location:
Inspected by:.
Date:
ID - Number to be used to identify problem on site sketch
G - Good, no action needed
F - Fair, monitor condition periodically, plan necessary repairs
P - Poor, immediate action needed
N/A - Not applicable

Area requires
cleaning
Improper draining
Sediment build-up
Adjacent area
requires mowing or
reseeding
Surface deterioration
or spalling
ID
1
2
3
4
5
G





F





P





N/A





REMARKS





                                                   F-12

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www.epa.gov/iaq/moisture
                                                       F-13

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                                                                                                www.epa.gov/iaq/moisture
REFERENCES
American Society for Testing and Materials (ASTM). ASTM
    D4263- Standard test method for indicating moisture in
    concrete by plastic sheet method.

American Society for Testing and Materials (ASTM). ASTM
    F1869-04- Standard test method for measuring moisture
    vapor emission rate of concrete subfloor anhydrous calcium
    chloride.

Claytor, R.A., and T.R. Schueler. Design of Stormwater Filtering
    Systems. The Center for Watershed Protection. (CWP)
    Silver Spring, MD. Prepared for the Chesapeake Research
    Consortium, Solomons, MD, and USEPA Region V, Chicago,
    IL. 1996.

Code of Federal Regulations (29 CFR). Title 29-  Labor.
    (Title 29 of the CFR outlines requirements of Occupational
    Safety and Health Administration [OSHA] for workers, which
    include standards for ladder use and maintenance.)
Forest Products Laboratory. Wood handbook: Wood as an
    engineering material. General Technical Report FPL-
    GTR-113. United States Department of Agriculture, Forest
    Service, Forest Products Laboratory. 1999.

James, William L. Electric Moisture Meters for Wood.  General
    Technical Report FPL-GTR-6. United States Department of
    Agriculture Forest Service, Forest Products Laboratory. June
    1988.

New Jersey Department of Environmental Protection, (NJDEP04).
    New Jersey Stormwater Best Management Practices Manual.
    Trenton, NJ. April 2004.
                                                           F-14

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www.epa.gov/iaq/moisture
 Appendix  G  - Dampness  & Mold  Evaluation
The National Institute for Occupational Safety and
Health (NIOSH) has developed an observational
assessment tool for dampness and mold in buildings.
As of October 1, 2013, the tool was in review to
become an official NIOSH document. The goal of
the tool is to provide information for motivating
remediation, prioritizing intervention, and evaluating
remediation effectiveness.

The tool consists of:
1.  A form used to evaluate signs of dampness, water
    damage,  mold growth, and  musty odors in rooms
    and areas throughout the building.
                                               2.  A Visual Basic® data entry application to enter
                                                   data collected from hard copy evaluation forms
                                                   for electronic record keeping and reports. Data
                                                   is stored  in a Microsoft Access® database. The
                                                   software may also be implemented on PC-based
                                                   tablets. The software is  under development.  Once
                                                   completed, the software will be made available at
                                                   http://www.cdc.gov/niosh/topics/indoorenv/mold.
                                                   html.

                                               For additional information or to receive a form and
                                               instructions for use, contact moldsheet#l@cdc.gov
                                               (mailto:  moldsheet#l@cdc.gov).
Figure G-1 NIOSH Dampness and Mold Assessment Form for Schools
       NIOSH PILOT-DRAFT    NIOSH CcnU.:! Michel c. u,in-n 3CW-zeE-E73J or tc-d'= "ooi? 1 .£cdcgov
                      Damoness & Mold Assessment Checklist
         Date:
                       Observer:
                                                    _Building:_
                                                                  _Wing:_
         Floor:
         G Classroom

         O Storage   o library

         o Stairwell   Other
           	Room Number:	

           O Office   o Hallway    c Conference room

                  o Cafeteria   oGym    o Auditorium
           _Room Type: Fiti the bubbte for the following room types.

           O Bathroom   o Custodial closet   O Mechanical room

               O Kitchen   o Locker room   o Entrance area
         MOLD ODOR  o NONE   o MILD   o MOO   o HEAVY  Source'.

         Be sure tu *m*li mold odor when you flr»t walk Into th« roomrar**-
                         NA
                         i.' j, .
        FHI the
        bubbles
        for each
        column and
        row.
                      DAMAGE
                      or STAINS
                      0=NONE
MOLD
AREA
0=MO«E
MOLD
DENSITY
0=NONE
WET or
DAMP
Q=NQNi
                                          3«HEAW
                               0123
                                         It 1 2 3
                                                   0123
                                                             0123
                                                                               o Source Unknown
                                                                                   NOTES
                                                                      Totals
        Colling
                                                 (3)
                     (5) (J) 
                                 :H: :'0
                     (J) (T>
                                 (0 <2>
        HVAC »yitem*
                         0)
     (2)
                 OB
        Pipes
        Furnishings
                                                   ©
                                           © ©
                                                     © ® © 3)
        Supplies & Material*

        Other
        Totals
        Average
                                     QJ
 ® © © ©
 ® © © CB
 @ ®
 ® ©
                                                           0)
                                                    G-1

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 Glossary
                                                                                  www.epa.gov/iaq/moisture
Term
Definition
Air barrier

Air handler

Alligator ing

ASHRAE
Asphalt

ASTM
Ballast

Bitumen
Blister
Built-up roofing
(BUR)
Cant strip
Capillary break

Chase
Cladding

CMU
Commissioning

Coping

Crack
Any material, combination of materials or manufactured assemblies that are intended, by
design, to control the movement of air across an exterior wall system or assembly.
Equipment that includes a blower or fan, heating or cooling coils and related equipment
such as controls, condensate drain pans and air filters. Does not include ductwork,
registers or grilles, or boilers and chillers.
Shrinkage cracking of the bituminous surface of built-up or smooth surface roofing,
producing a pattern of deep  cracks resembling alligator hide.
American Society of  Heating, Refrigeration, and Air-Conditioning Engineers, Inc.
A highly viscous hydrocarbon produced from the residue left over after the distillation of
petroleum. Asphalt is used to water-proof built-up roofs.
American Society for Testing and Materials.
An anchoring material such as rock, gravel or pavers used to resist wind uplift forces on
roof membranes.
A generic term for asphalt or coal tar pitch roofing.
A spongy raised portion of a  roofing membrane as a result of pressure of entrapped air or
water vapor.
A continuous semi-flexible roof covering consisting of laminations or piles of saturated or
coated felts alternated with layers of bitumen.
A continuous strip of triangular cross-section fitted into the angle formed  by a structural
deck and a wall or other vertical surface. Used to provide a gradual transition for base
flashing and horizontal roof membrane.
A slot or groove intended to create  an opening too large to  be bridged by a drop of water
in order to eliminate the passage of water by capillary action.
A groove or indentation cut into masonry to accommodate electric or plumbing lines.
A panel applied to a  structure to provide durability, weathering, corrosion  and  impact
resistance.
Concrete masonry  unit.
Start-up of a building that includes testing and  adjusting HVAC, electrical, plumbing
and other systems to ensure proper functioning and adherence to design criteria;  also
includes the instruction of building representatives in the use of the building systems.
The material or units used to form  a cap or finish on top of a wall, pier, pilaster or
chimney; a protective cap at the top of a masonry wall. It should  be waterproof, weather
resistant and sloped  to shed water.
A break in a roofing membrane as a result of flexing, often  occurring along a ridge or
wrinkle.
                                                   H-l

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www.epa.gov/iaq/moisture
 Term              Definition
 Cricket

 Drainage or drain
 plane
 Dry well

 Eave
 Enthalpy
 EPDM

 Expansion joint

 Fascia
 Fishmouth
 Flashing


 Fore bay

 Gravel stop

 HVAC
 Hygrothermal
 Impervious
 Micromanometer
 Modified bitumen

 OSB
 Parapet
 Plenum

 Ponding
A chimney flashing on the uphill side, resembling a small roof ridge, to divert rainwater
around the chimney.
Any element exposed to weather or otherwise residing at the line between the "wet" and
"dry" zones of an exterior wall system or assembly.
A deep hole, covered and usually lined or filled with rocks, that  holds drainage water
until it soaks  into the ground.
The protective overhang at the lower edge of a sloped roof.
A measure of the total energy of a thermodynamic system. It includes the internal energy,
which is the energy required to create a system, and the amount of energy required to
make room for it by displacing its  environment and establishing its volume and pressure.
Ethylene propylene diene monomer, a synthetic rubber sheet used in single-ply roof
membranes.
A deliberate separation of two roof areas to allow expansion and contraction movements
of the two parts.
The finish covering the edge of eaves of a flat or sloping roof or roof overhang.
An opening of the lapped edge of applied felt in built-up roofing due to adhesion failure.
Connecting devices that seal membrane joints, drains, gravel stops and other places
where membrane is interrupted. Base flashing forms the upturned edges of the watertight
membrane. Cap or counter flashing shields the exposed edges and joints of the base
flashing.
A small pool located near the inlet of a storm basin  or other storm water management
facility. These devices are designed as initial storage areas to trap and settle out
sediment and heavy pollutants before they reach the main basin.
A flanged device, normally metallic, designed to prevent loose aggregate from washing
off the roof. It also provides the finished  edge detail for built-up roofing assemblies.
Heating, ventilation and air conditioning.
Pertaining to  heat and humidity.
Not letting water or moisture pass through or be absorbed.
An instrument designed to measure minute differences in pressure.
Asphalt with the addition of polymer modifiers to increase cold temperature flexibility
and warm temperature flow resistance and  stability.
Oriented Strand Board. A type of particle panel product composed of strand-type flakes
that are purposefully aligned in directions that  make a panel stronger, stiffer and with
improved dimensional properties in the alignment directions than a panel with random
flake orientation.
The part of the  wall assembly above the roof.
Space between  a suspended ceiling and the floor above that may have mechanical and
electrical equipment in it and that is used as part of the air distribution system. The
space is usually designed to be under negative pressure.
The collection of water in shallow  pools on a roof surface.

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                                                                                 www.epa.gov/iaq/moisture
Term
Definition
PVC
R-value
Scuppers
Section

Shingle-wise

Slope
SMACNA
Soffit
Spall

Stem wall
Sump crock
Swale

TAB
Tensiometer
Vapor barrier

WBDG
Weep Holes
A generic term for single-ply plastic sheet membrane (polyvinyl chloride). Seams are
fused by solvent or hot-air welding techniques.
The number of minutes (seconds) required for 1 Btu (joule) to penetrate one square foot
(square meter) of a material for each degree of temperature difference between the two
sides of the material. The resistance of a material to the passage of heat. The reciprocal
of conduction (1/c).
An opening for draining water, as from a floor or the roof of a building.
A drawing showing the kind,  arrangement and proportions of the various parts of a
structure.  It shows how the structure would appear if cut through by a plane.
The overlapping of materials shingle style so that impinging water,  such as rainwater, will
run harmlessly down and out.
The ratio between the measures of the rise and the horizontal span.
Sheet Metal and Air Conditioning Contractors' National Association.
The finish on the underside of the roof overhang.
A fragment, usually in the shape of a flake, detached from a larger mass by a blow, by
the action of weather, by pressure or by expansion within the larger mass.
The vertical part of a concrete or masonry retaining wall.
A hole designed to collect water and other spilled fluids.
A vegetated, open-channel management practice designed to treat and attenuate runoff
for specified water quality and volume.
Test, adjust and balance.
An instrument used to measure the surface tension of liquids.
Material used to retard the movement of water vapor into walls and prevent condensation
in them; applied separately over the warm side of exposed walls or as a part of batt or
blanket insulation.
Whole Building Design Guide.
Small openings left in the outer wall of masonry construction as an outlet for water inside
a building to move outside the  wall and evaporate.
                                                  H-3

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         V
Indoor Air Quality (IAQ)

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