For more information
www.energystar.gov
orcall1.888.STAR.YES
(1.888.782.7937).
United States
Environmental
Protection Agency
Office of Air and Radiation
(6202J)EPA430-F-04-024
September 2006
A DO-IT-YOURSELF GUIDE
TO ENERGY STAR8 HOME SEALING
SEALING AIR LEAKS AND ADDING ATTIC INSULATION
Recycled/Recyclabl
ENERGYSTAR
-------
ENERGYSTAR
HOME SEALING
EPA recommends
sealing air leaks
and adding
insulation to
make your home
more
comfortable,
reduce energy
bills, and help our
environment
Home Sealing is one of the most
cost-effective ways to make a
home more comfortable and
energy efficient- and you can
do it yourself.
Use This Guide To:
1. Learn howto find and seal hidden
attic and basement air leaks
2. Determine if your attic insulation
is adequate, and learn howto
add more
3. Make sure your improvements
are done safely
4. Reduce energy bills and help
protect the environment
CONTENTS
Locating Air Leaks
1.2
Getting Started
1.4
Sealing Attic Air Leaks
1.6
Additional Sources of Air Leaks
2.1
Sealing Basement Air Leaks
3.1
Adding Attic Insulation
4.1
When you see products or services with
the ENERGY STAR® label, you know they
meet strict energy efficiency guidelines
set bythe U.S. Environmental Protection
Agency (EPA) and the U.S. Department
of Energy (DOE). Since using less energy
reduces greenhouse gas emissions and
improves air quality, choosing ENERGY
STAR is one way you can do your part to
protect our planet for future generations.
For more information visit:
www. energystar.gov
orcall1.888.STAR.YES
(1.888.782.7937).
The U.S. EPAwishesto thankThe Family
Handyman Magazine for their contribution
of photographs and content for this guide.
Photos appear courtesy of The Family
Handyman Magazine ©2001 except
where otherwise noted.
1.1 CONTENTS
-------
LOCATING AIR LEAKS
More than any other time of year, you notice your home's air leaks in the winter. Most people call
these air leaks "drafts." You may feel these drafts around windows and doors and thinkthese leaks
are your major source of wasted energy. In most homes, however, the most significant air leaks are
hidden in the attic and basement. These are the leaks that significantly raise your energy bill and
make your house uncomfortable. In cold weather, warm air rises in your house, just like it does in a
chimney. This air, which you have paid to heat, is just wasted as it rises up into your attic and sucks
cold air in all around your home - around windows, doors, and through holes into the basement.
The illustrations on Page 1.3 and 3.1 show warm air leaving (red arrows) the house through the attic
and cold air being pulled into the house (blue arrows). Locating these leaks can be difficult because
they are often hidden under your insulation. This guide will help you find these leaks and seal them
with appropriate materials.
Even if you have enough
insulation in your attic, sealing
attic air leaks will enhance the
performance of your insulation
and make for a much more
comfortable home.
If you are not familiar with
some of the terms in this guide,
check our glossary inside the
back cover.
Common Household
Air Leaks
^J Behind Kneewalls
^3 Attic Hatch
%y Wiring Holes
fy Plumbing Vent
Open Soffit (the box that hides
recessed lights)
Recessed Light
Furnace Flue or Duct Chaseways
(the hollow box or wall feature that
hides ducts)
Basement Rim Joists (where the
foundation meets the wood framing)
Windows and Doors
Effects of Air Leaks
[^^ Cold outside air drawn into the house
Heated inside air drawn into the attic
1.2 LOCATING AIR LEAKS
1.3 LOCATING AIR LEAKS
-------
GETTING STARTED
You May Need a Contractor
to Correct These Problems:
• Wet or damp insulation indicating a
leaky roof
• Moldy or rotted attic rafters or floor
joists indicating moisture problems
• Kitchen, bathroom, and clothes
dryer vents that exhaust moist air
directly into the attic space instead
of outdoors
• A history of ice dams in the winter
(an indication of serious air leaks)
• Little or no attic ventilation (see Page
4.2 - A Note About Attic Ventilation)
• Knob and tube wiring (pre-1930),
which can be a fire hazard when in
contact with insulation
• If you have many unsealed and
uninsulated recessed "can" lights,
special care must be taken when
insulating around these fixtures
(See Page 2.2)
Attic air sealing and adding insulation
are do-it-yourself projects if your attic is
accessible and not too difficult to move
around in. The projects recommended in
this guide can usually be completed in a
day or two and will provide benefits for
years to come. However, if upon inspection
of your attic you find any of the conditions
listed to the left, we recommend you
consider hiring a contractor to correct
these problems before proceeding.
For tips on hiring the right contractor, visit
www.energystar.gov/homeimprovement.
Get Your Bearings
from Below
A good way to start home sealing is to
make a quick sketch of your home's floor
plan. This sketch will serve as a reference
point once you get into the attic and will
help you locate areas of leakage. In your
sketch, make note of dropped soffits over
kitchen cabinets or bath vanities, slanted
ceilings over stairways, where walls
(interior and exterior) meet the ceiling, and
any other dropped-ceiling areas. These
areas may have open stud cavities leading
directly into the attic and can be huge
sources of air leaks (see photos 1-3 on
Pages 1.6 and 1.7).
Tips For Working in the Attic
• Have a Plan in Place
The key to any successful home
improvement project is adequate
planning. Gather all yourtools and
supplies before you begin to minimize trips
in and out of the attic. Be sure that the
work area is well-lit by using a drop light,
and keep a flashlight handy.
• Prepare to Get Dirty
The entire process of sealing your attic
will be made easier if you take the time
and effort to wear the right gear. Wear
knee pads to help prevent pain associated
with crawling on attic joists. Additionally,
a lightweight disposable coverall, gloves,
and hat can keep itchy and irritating
insulation off your skin.
Above All - Be Safe
Take precautions to avoid a dangerous
working environment in the attic. During
hot weather start working early, as attics
heat up as the day moves on. Drink plenty
of water and use an OSHA-approved
particulate respirator or double-strap
dustmaskto prevent inhalation of
hazardous substances. Also remember
to watch your step. Walk on joists or
truss chords, not exposed ceiling drywall
or insulation. In addition, watch out for
sharp nails sticking through the
roof deck!
Materials Checklist for Sealing Attic Air Leaks
1.4 GETTING STARTED
Batt or roll of unfaced fiberglass insulation
and large garbage bags (for stuffing open
stud cavities behind kneewalls and in
dropped soffits)
Roll of reflective foil insulation or other blocking
material such as drywall or pieces of rigid foam
insulation to cover soffits, open walls, and
larger holes
Silicone or acrylic latex caulk & caulk gun for
sealing small holes (1/4 inch or less)
Several cans of expanding spray foam insulation
for filling larger gaps (1/4 inch to 3 inches)
Special high-temperature (heat-resistant) caulk
to seal around flues and chimneys
Roll of 14-inch wide aluminum flashing to keep
insulation away from the flue pipe
Retractable utility knife and sheet metal scissors
Tape measure and staple gun (or hammer and
nails) to hold covering materials in place
Safety glasses, gloves, and dust mask
(for insulation work as well)
Flashlight or portable safety light
Boards to walk on, if needed
Large bucketto haul materials
1.5 GETTING STARTED
-------
SEALING ATTIC AIR LEAKS
Plug the Big Holes First
Don't worry about finding and sealing all the little holes in your attic; your biggest savings
will come from plugging the large ones. Once in the attic, referto your sketch to locate
the areas where leakage is likely to be greatest: where walls (inner and outer) meet the
attic floor, dropped soffits (dropped-ceiling areas), and behind or under attic kneewalls.
Look for dirty insulation-this indicates that air is moving through it. Dropped soffits may
be filled or covered with insulation and hard to see. Push backthe insulation and scoop it
out of the soffits. You will place this insulation back overthe soffit once the stud cavities
have been plugged and the soffits covered (photos 1-3) (If you have recessed "can" lights
in your open soffits, please read about them on Page 2.2 before proceeding).
3. COVER DROPPED SOFFITS
4. SEAL BEHIND KNEEWALLS
1. CREATE STUFFED BAGS
2. PLUG OPEN STUD CAVITIES
Cut a 16 inch long piece from a batt of unfaced
fiberglass insulation and fold it into the bottom
of a 13-gallon plastic garbage bag.
Fold the bag and stuff it into the open stud cavity.
Add more insulation to the bag if it doesn't fit
tightly. Plug all open stud spaces, then cover the
soffit (photo 3, Page 1.7).
After removing insulation from a dropped soffit, cut
a length of reflective foil or other blocking material
(rigid foam board works well) a few inches longer
than the opening to be covered. Apply a bead of
caulk or adhesive around the opening. Seal the foil
to the frame with the caulk/adhesive and staple or
nail it in place, if needed.
Cut a 24 inch long piece from a batt of fiberglass
insulation and place it at the bottom of a 13-gallon
plastic garbage bag. Fold the bag over and stuff it
into the open joist spaces underthe wall (a piece of
rigid foam board sealed with spray foam also works
well for covering open joist cavities). Again, cover
with insulation when you're done.
If You Have a Finished Attic, Seal Behind the Kneewalls
Finished rooms built into attics often have open cavities in the floor framing underthe
side-walls or kneewalls. Even though insulation may be piled against or stuffed into these
spaces, they can still leak air. Again, look for signs of dirty insulation to indicate air is
moving through. You need to plug these cavities in order to stop air from traveling under
the floor of the finished space (photo 4).
Caution: Some attics have vermiculite insulation, which may contain asbestos, a health
hazard. Vermiculite is a lightweight, pea-size, flaky gray mineral. Don't disturb vermiculite
insulation unless you've had it tested by an approved lab to be sure it doesn't contain
asbestos. Contact your local health department for the name of an approved lab.
1.6 SEALING ATTIC AIR LEAKS
1.7 SEALING ATTIC AIR LEAKS
-------
SEALING ATTIC AIR LEAKS
Furnace Flues Require Special Sealing Techniques
The opening around a furnace or water heater flue or chimney can be a major source of
warm air moving in the attic. Because the pipe gets hot, building codes usually require 1
inch of clearance from metal flues (2 inches from masonry chimneys) to any combustible
material, including insulation. Photos 5 and 6 show how to seal this gap with lightweight
aluminum flashing and special high-temperature (heat-resistant) caulk. Before you push
the insulation back into place, build a metal dam (photo 7) to keep it away from the pipe.
Use the same technique for masonry chimneys.
6. SEAL WITH SILICONE CAULK
7. FORM AN INSULATION DAM
Caution: Furnace flues (the
pipe that removes your furnace
exhaust) can be very hot.
5. CUT ALUMINUM FLASHING
Cut aluminum flashing to fit around the flue. For
round flues, cut half circles out of two pieces so
they overlap about 3 inches in the middle. Press
the flashing metal into a bead of high-temperature
caulk and staple or nail it into place. If there's no
wood, staple or nail it directly to the drywall, but
be sure notto staple or nail through the drywall.
Seal the gap between the flue and metal flashing
with special high-temperature caulk. Don't use
spray foam.
Identifying Attic Pipes
Form an insulation dam to prevent insulation from
contacting the flue pipe. Cut enough aluminum from
the coil to wrap around the flue plus 6 inches. Cut
slots! inch deep and a few inches apart along the
top and bend the tabs in. Cut slots about 2 inches
deep along the bottom and bend out the tabs. Wrap
the dam around the flue and secure the bottom by
stapling through the tabs. Now put insulation back
right up against the dam.
FLUES/VENTS/PIPES: MADE OUT OF: SEAL AROUND WITH:
Furnace/Water Heater
Chimney
Plumbing
Galanized Metal
Masonry/Metal
Cast Iron or PVC
Aluminum flashing and high-
temperature silicone caulk
Aluminum flashing and high-
temperature silicone caulk
Expanding foam or caulk,
depending on size of gap
1.8 SEALING ATTIC AIR LEAKS
1.9 SEALING ATTIC AIR LEAKS
-------
SEALING ATTIC AIR LEAKS
Foam or Caulk Small Gaps in Your Attic
Even though most of the gaps spilling warm air into your attic are buried under insulation,
you might be able to find evidence of these gaps. Look for areas where the insulation
is darkened (see photo 8). This is the result of filtering dusty air from the house. In cold
weather, you may also see frosty areas in the insulation caused by warm, moist air
condensing and then freezing as it hits the cold attic air. In warmer weather, you'll find
water staining in these same areas. Although the insulation is dirty, it is still okay to use.
There's no need to remove and replace. After sealing the areas, just push the insulation
back into place. If you have blown insulation, a small rake can be helpful to level it back
into place.
Seal Small Gaps
Use expanding foam or caulkto seal the openings around plumbing vent pipes and
electrical wires (see photos 9 and 10). Be sure to wear gloves and be careful not to get
expanding foam on your clothes, as the foam is very sticky and nearly impossible to
remove once it sets. When the foam or caulk is dry, coverthe area again with insulation.
8. FIND ATTIC BYPASSES
9. FILL HOLES WITH CAULK
10. STUFF GAPS WITH INSULATION
Check for gaps in your attic that facilitate air
movement by checking for dirty insulation. Seal the
gaps with caulk or expanding foam. When complete
and dry, push the insulation back into place.
Fill wiring and plumbing holes with expanding foam.
Caulk around electrical junction boxes, and fill
holes in box with caulk.
If the space around your plumbing pipe is wider
than 3 inches, you may need to stuff some
fiberglass insulation into the space to serve as a
backer for the expanding foam. Once the fiberglass
insulation is in place, follow the directions on the
can to foam the space around the pipe.
1.10 SEALING ATTIC AIR LEAKS
1.11 SEALING ATTIC AIR LEAKS
-------
SEALING ATTIC AIR LEAKS
ADDITIONAL SOURCES OF AIR LEAKS
Complete the Job by Sealing the Attic Hatch or Door
Finish up by sealing the access hatch with self-sticking weather stripping (photos 11 and
12). If your hatch rests directly on the moldings, add 2-1/2 inch wide stops around the
opening. The stops provide a wider surface for attaching the weatherstrip and a space
to mount hook-and-eye fasteners. Position the screw eyes so the weatherstrip is slightly
compressed when the hooks are latched. Cut a piece of fiberglass or rigid foam board
insulation the same size asthe attic hatch and nail or glue it to the back of the hatch.
If you have pull-down attic stairs or an attic door, these should be sealed in a similar
manner: weatherstrip the edges and put a piece of rigid foam board insulation on the back
of the door. Treat the attic door like a doorto the outside. Pre-made insulated attic stair
covers are also available from local home improvement centers or on the Web.
11. WEATHERSTRIP THE DOOR
12. ATTACH FASTENERS
Weatherstrip the attic access hatch or door. Cut 1x3
boardsto fit the perimeter of the opening and nail
them on with 6d finish nails. Apply self-adhesive
foam weatherstrip tape to the top edge of the stop.
Attach hook-and-eye fasteners to the attic door and
stops. Position the eyes so that the weatherstrip is
compressed when you latch the hooks.
If Your Heating and Cooling Ducts Are in Your Attic,
Seal Them While in the Attic
Leaky and poorly-insulated ducts (especially in attics) severely compromise the
performance of your heating and cooling equipment. Sealing and insulating your ducts
can increase the efficiency of your heating and cooling system by 20% and greatly
increase airflow.
Checkthe duct connections for leaks
by turning on your heating and cooling
system fan and feeling for leaks - seal the
joints with mastic or foil tape (household
duct tape should not be used).
Pay special attention to all the duct
penetrations going through the attic floor.
Seal these with foam.
Ducts should also be insulated - if your
ducts are uninsulated or poorly insulated
(i.e.,you see gaps ortorn insulation), seal
them first, then add insulation to keep the air
in your ducts at your desired temperature
as it moves through the system. Use duct
insulation material rated at least R-6.
Materials Checklist
for Attic Duct Sealing
• Duct sealant (mastic) or metal-
backed (foil) tape
• Duct insulation material rated at
least R-6
• Zip ties to hold duct insulation
in place
• Gloves, safety glasses, mask,
flashlight
NOTE: Duct sealant, also known as duct mastic,
is a paste which is more durable than foil duct
tape. It is available at home improvement centers.
Traditional grey duct tape fails quickly and
should not be used.
Caution: Check for Carbon Monoxide to keep your house safe. After making energy
improvements that result in a tighter house, there can be an increased opportunity for CO
to build up if your gas-burning appliances are not venting properly. Have your heating and
cooling technician check your combustion appliances (gas- or oil-fired furnace, water heater,
and dryer) for proper venting. For additional information on Indoor Air Quality (IAQ) issues
related to homes such as combustion safety, indoor air contaminants, and proper ventilation,
visitwww.epa.gov/iaq/homes/hip-front.html.
1.12 SEALING ATTIC AIR LEAKS
2.1 ADDITIONAL SOURCES OF AIR LEAKS
-------
ADDITIONAL SOURCES OF AIR LEAKS
SEALING BASEMENT AIR LEAKS
Recessed "Can" Lights: Big Source of Air Leaks,
But No Easy Solution
Recessed "can" lights (also called high-hats or recessed downlights) look great, but
when they protrude into your attic space, they can make your home less energy-efficient.
These recessed lights in a one-story house or in the ceiling of a second-story create
open holes into your attic that allow unwanted heat flow between conditioned and
unconditioned spaces. In the summer, hot attic air can make the rooms warmer, and in
the winter can lights draw warm air up into your attic. Both the warm air leakage and the
heat from the lights can cause problems. In cold climates, the heat melts snow on the
roof and forms ice dams (water re-freezes at the roof edge). This is more likely to happen
if the "can" light is close to the roof deck. Recessed "can" lights in bathrooms also cause
problems when warm, moist air leaks into the attic and causes moisture damage. Here
are some suggestions for improving the recessed can lights in your attic:
Call a Professional to Properly Seal
Recessed lights can be sealed, but it is difficult
and can create a hazard if not done properly with
non-combustible materials. Since any old-style
lights need adequate air space around them to
vent the heat they create, it's best to consult with
a professional before sealing them. Also, see
"Caution" below. Alternatively, recessed lights
can be replaced with ICAT (Insulated Ceiling Air-
Tight) rated lights, which insulation can touch and
are sealed to reduce air leaks.
When Replacing or Adding, Buy
ENERGY STAR with ICAT
Look for ENERGY STAR qualified recessed fixtures
that reduce energy use as much as 75%. However,
it's importantto checkthat any fixture selected
meets your light output expectations since fixtures
come with widely varying wattage bulbs and
optics. Also, make sure fixtures have an ICAT
rating to minimize heat loss.
2.2 ADDITIONAL SOURCES OF AIR LEAKS
Switch to More Efficient Bulbs
When keeping existing recessed lights, you
can still reduce lighting energy use as much
as 75% by installing ENERGY STAR qualified
compact fluorescent light (CFL) bulbs. This
includes CFL bulbs specifically designed
for recessed lights with built-in reflectors
matching the appearance of traditional
incandescent reflector bulbs. As with new
fixtures, it is importantto make sure any
CFL bulb selected meets your light output
expectations. Also, checkthe packaging of
the CFLto ensure that it may be used in an
enclosed fixture. However, switching to CFL
bulbs will not solve the air leakage problem.
Caution: Keep all insulation 3 inches
from "can" lights, except those rated
1C (insulation contact). You can use
a piece of circular metal flashing or
wire mesh around the light as a dam
to keep the insulation away from the
light (see photo 2, Page 4.3).
Stopping the Chimney Effect
Outside air drawn in through basement leaks
is exacerbated by the chimney effect created
by leaks in the attic. As hot air generated
by the furnace rises up through the house
O and into the attic through leaks @, cold
outside air gets drawn in through basement
leaks to replace the displaced air©. This
makes a home feel drafty and contributes
to higher energy bills. After sealing attic air
leaks, complete the job by sealing basement
leaks, to stop the chimney effect.
Locating Basement Air Leaks
A common area of air leakage in the basement is along the top of the basement wall
where cement or block comes in contact with the wood frame. These leaks can easily be
fixed in portions of the basement that are unfinished. Since the top of the wall is above
ground, outside air can be drawn in through cracks and gaps where the house framing
sits on top of the foundation. This perimeter framing is called the rim (or band) joist. In the
basement, the above floor joists end at the rim joist creating multiple cavities along the
length of the wall, and many opportunities for leakage (see illustration on Page 3.2).
3.1 SEALING BASEMENT AIR LEAKS
-------
SEALING BASEMENT AIR LEAKS
Seal All Gaps and Cracks around Rim Joists
Though you may not be able to see cracks in the rim joist cavities, it is best to seal up
the top and bottom of the inside of the cavity. Also, rim joist air sealing is especially
important at bump out areas such as bay windows that hang off the foundation. These
areas provide greater opportunities for air leakage and heat loss. Caulk is best for sealing
gaps or cracks that are 1/4 inch or less. Use spray foam to fill gaps from 1/4 inch to about
3 inches. We also recommend you seal penetrations that go through the basement ceiling
to the floor above. Generally, these are holes for wires, water supply pipes, water drain
pipes, the plumbing vent stack (for venting sewer gases), and the furnace flue (for venting
furnace exhaust).
Materials Checklist for
Basement Sealing
• Silicone or acrylic latex caulk and caulk gun
• Expanding spray foam
Areas to Foam or Caulk
Caution: When sealing the furnace
flue (which will be encased in a
metal sleeve) use high-temperature
caulk. Run a bead of high-
temperature caulk around the pipe
sleeve and around the metal frame.
Along the gap between the sill
plate and the foundation
At the bottom and top of the rim
joist on each end of the house
All electrical, water, or gas
penetrations and any venting
ducts that pass to the outside
ILLUSTRATION BY DALE HOFFMEYER
3.2 SEALING BASEMENT AIR LEAKS
What About Insulating the Rim Joist?
After air sealing the rim joist area it is relatively easyto insulate each cavity with rigid
foam insulation or fiberglass batts. If using batts, just cut the insulation to fit and place
against the rim joist without compression, gaps, or voids. If using rigid, foam into place.
This could also be done in conjunction with finishing the basement, when you would
insulate the basement walls floor-to-ceiling. Attic and basement air sealing will go
a long way to improve your comfort because your house will no longer act like an
open chimney.
ADDING ATTIC INSULATION
Now that you've air-sealed your attic and basement, check your attic insulation levels
and add more if necessary. The attic is the easiest place to add insulation to improve your
comfort and the energy efficiency of your home.
Do I Have Enough?
No matter what kind of insulation you currently have in your attic, one quick way to
determine if you need more is to look across the span of your attic. If your insulation is
just level with or below your floor joists (i.e., you can easily see your joists), you should
add more. If you cannot see any of the floor joists because the insulation is well above
them, you probably have enough and adding more may not be cost-effective. It is
important that the insulation be evenly distributed with no low spots; sometimes there
is enough insulation in the middle of the attic and very little along the eaves. To see how
to add insulation out to the eaves, see Installing Rafter Vents (on Page 4.4). If your attic
insulation covers your joists and is distributed evenly, you probably have enough.
How Much Should I Add?
Insulation levels are specified by R-Value. R-Value is a measure of insulation's ability
to resist heat flow. The higher the R-Value, the better the thermal performance of the
insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14
inches, depending on insulation type.
4.1 ADDING ATTIC INSULATION
-------
ADDING ATTIC INSULATION
A Note about Natural
Attic Ventilation
At first it may seem odd to add insulation for warmth
and then purposely allow cold airto enterthe attic
through vents, but this combination is the keyto a
durable and energy-efficient home. Here's why: in the
winter, allowing a natural flow of outdoor airto ventilate
the attic helps keep it cold, which reduces the potential
for ice damming (snow that melts off a roof from an
attic that is too warm and then re-freezes at the gutters,
causing an ice dam that can damage the roof). Proper
insulation and air sealing also keeps attics cold in
winter by blocking the entry of heat and moist air from
below. In the summer, natural air flow in a well-vented
attic moves super-heated air out of the attic, protecting
roof shingles and removing moisture. The insulation will
resist heat transfer into the house. The most common
mistake homeowners make when installing insulation
isto blockthe flow of air at the eaves. NEVER COVER
ATTIC SOFFIT VENTS WITH INSULATION - use rafter
vents and soffit vents to maintain airflow (See Pages 4.4
and 4.5).
A Note about Attic Fans
Attic fans are intended to cool hot attics by drawing
in cooler outside air from attic vents (soffit and gable)
and pushing hot air to the outside. However, if your attic
has blocked soffit vents and is not well-sealed from the
rest of the house, attic fans will suck cool conditioned
air up out of the house and into the attic. This will
use more energy and make your air conditioner work
harder, which will increase your summer utility bill.
You don't want your unfinished attic cooled by your air
conditioner. To prevent this, follow the air sealing and
insulation strategies in this guide and make sure the
attic is well-ventilated using passive vents and natural
airflow.
Use a blowing machine to blow in loose
fill insulation.
Photo courtesy of Green Fiber
Add the Right Kind
of Insulation
When adding additional insulation, you do
not have to use the same type of insulation
that currently exists in your attic. You
can add loose fill on top of fiberglass
batts or blankets, and vice-versa. If you
use fiberglass over loose fill, make sure
the fiberglass batt has no paper or foil
backing; it needs to be "unfaced." If you
choose to add loose fill, it may be wise
to hire a professional, as the application
requires the use of a blowing machine,
although some home improvement stores
offer rentals of this machine.
Doing the Job
Laying fiberglass rolls is easiest for a DIY job. If you have any type of insulation between
the rafters, install the second layer over and perpendicular to the first (again, the second
layer of roll insulation should be unfaced-with no vapor retarder). This will help cover
the tops of the joists and reduce heat loss or gain through the frame. Also, when laying
down additional insulation, work from the perimeter toward the attic opening. Never lay
insulation over recessed light fixtures or soffit vents. Keep all insulation at least 3 inches
away from "can" lights, unless they are rated 1C (Insulated Ceiling). If you are using loose
fill insulation, use sheet metal to create barriers around the openings. If using fiberglass,
wire mesh can be used to create a barrier.
1. LAY FIBERGLASS ROLLS
2. CREATE A BARRIER
Layer fiberglass roll insulation perpendicular
to the joists.
Photo courtesy North American Insulation
Manufacturers Association
Use sheet metal or wire mesh to help create a
barrier around fixtures or vents.
4.2 ADDING ATTIC INSULATION
4.3 ADDING ATTIC INSULATION
-------
ADDING ATTIC INSULATION
Installing Rafter Vents
To completely cover your attic floor with insulation out to the eaves you need to install
rafter vents (also called insulation baffles). Complete coverage of the attic floor along
with sealing air leaks will ensure you get the best performance from your insulation.
Rafter vents ensure the soffit vents are clear and there is a channel for outside air to
move into the attic at the soffits and out through the gable or ridge vent (see Attic Air
Flow graphic on Page 4.5).
To install the rafter vents, staple them directly to the roof decking. Rafter vents come
in 4-foot lengths and 14-1/2 and 22-1/2 inch widths for different rafter spacings.
Rafter vents should be placed in your attic ceiling in between the rafters at the point
where your attic ceiling meets your attic floor. Once they are in place, you can then
place the batts or blankets, or blow insulation, right out to the very edge of the attic
floor. Note: Blown insulation may require an additional blockto prevent insulation from
being blown into the soffit (see Page 4.5). A piece of rigid foam board placed on the outer
edge of the top plate works very well for this.
3. PLACE RAFTER VENTS
4. ADD INSULATION
Place rafter vents in between the rafters where
the ceiling meets the floor.
Photo courtesy of Doug Anderson
Add insulation around the rafter vent and out to
the edge of the attic floor.
Photo courtesy of Doug Anderson
Attic Air Flow
The outside air flows through the soffit,
along the rafter vent and out through
the gable or ridge vent.
^ RAFTER VENT
(3 SOFFIT VENT
Q RIDGE VENT
NOTE: Gable vent not
shown in this diagram.
ILLUSTRATION ©FAMILY HANDYMAN MAGAZINE
For additional information on Indoor Air Quality (IAQ) issues related to homes such as combustion safety,
indoor air contaminants, and proper ventilation, visit: http://www.epa.gov/iaq/homes/hip-front.html.
GLOSSARY
ENERGY STAR - ENERGY STAR is a government-backed
program helping businesses and individuals protect the
environment through superior energy efficiency. To learn
more about the wide variety of energy-efficient ENERGY STAR
products and processes visit http://www.energystar.gov.
ENERGY STAR Home Sealing-A process recommended by
the ENERGY STAR Program for improving the envelope of
a home to make it more comfortable and energy-efficient.
The process includes sealing air leaks and adding insulation
where cost-effective.
Air Duct-A hollow conduit or tube (square or round) that
circulates air from a forced-air heating and/or cooling system
to a room (supply duct) or returns air back to the main system
from a room (return duct).
Air Leak-A hole, crack, or gap where air can leak in or
out of a house. Air leaks can make a home feel drafty or
uncomfortable and waste energy (See Page 1.3).
Gable Vent-A screened vent installed at or near the peak of
a roof gable that allows warm attic air to escape.
Insulation - A material that is designed to slow down the flow
of heat in or out of a building structure.
Joist-A beam used to support floors or roofs (See Page 3.2).
Kneewall-A short wall in a room with a sloped ceiling. It is
usually formed when the room ceiling follows the roof line of
a house (See Page 1.3).
Rafter Vent-A vent leading from the soffit into the attic
through the space between the attic rafters. This vent allows
air to correctly flow past insulation into the attic space (See
Pages 4.4 or 4.5).
Recessed "Can" Light-A metal light fixture (or can) that is
in-set into the ceiling. These fixtures can be a big source of air
leaks when installed in the upper floor of a home (See Pages
1.6 and 4.3).
Ridge Vent-A screened vent installed along the top ridge of a
roof that allows warm attic air to escape (See Page 4.5).
Sill Plate-A wood plank that lays flat on top of a concrete or
masonry foundation or wall that supports a floor or ceiling joist
(See Page 3.2).
Soffit-The underside of a building overhang, beam, or arch,
especially the underside of a stair or roof overhang (See
Page 4.5).
Soffit Vent-A screened vent in a house soffit that allows air
to flow into the attic or the space below the roof sheathing.
This helps keep the attic cool in the summer and allows
moisture in the attic to evaporate (See Page 4.5).
4.4 ADDING ATTIC INSULATION
4.5 ADDING ATTIC INSULATION
------- |