Questions and Answers from the
Mold and Moisture Webinar
Table of Contents
Building Materials
Carpet Cleaning
Drywall
HVAC Units
Temperature
Building Materials
O: I live in the Southwest where most of the structures are built with stucco. In regards to mold and
moisture issues, what should we be looking for in comparison to brick buildings?
A: The principles of moisture drive are relatively the same in a brick or stucco building. The key
to mold control is placement of the vapor barrier (exact location is dependent on geographic
location and climate). To minimize water intrusion through cracks and joints of the plaster,
ensure that proper damp-proofing is installed directly behind the plaster surface.
O: What is the best way to search behind brick for mold?
A: We drop a small "pencil" camera down behind the brick. It is important to remove a few
pieces of brick high in the wall and ensure that there is enough space between the brick and
back-up to allow camera access.
O: Is fiberglass mold resistant?
A: Fiberglass does not, by itself, promote mold growth; however, the paper facer and dirt and
debris that collects in and on fiberglass does promote mold growth.
O: Do issues arise with moisture intrusion fi'om below the slab vapor barriers?
A: Yes. Depending on the type of flooring in place and the moisture content of the soil, moisture
seeping up through the slab or through below-grade walls can cause mold issues.
O: What is CMU?

-------
A: CMU stands for "concrete masonry unit" (cinderblock).
Q: Mortar build up behind walls seems inevitable at our school; what is your recommendation to
address this issue?
A: We have had great success with the use of mortar nets, which are approximately 12 inches in
height. In addition, we have stringent quality control procedures to ensure our contractor is
cleaning the back side of the brick.
Carpet Cleaning
Q: Those who don't use dry extraction methods put a lot of moisture into their building. Do you have
any experience with moldy carpet or humidity-removal issues due to the wet cleaning of carpet?
A: The flooring that we typically refer to as "carpet" is a non flow-through, bonded, vinyl-
backed and fiber surface product. This flooring is called vinyl cushion tufted textile (or VCTT).
The six foot seams are welded so water will stay on top of the floor. Cleaning and drying of this
type of flooring is easier and safer than cleaning and drying foam-backed flooring.
We also have truck-mounted steam cleaning equipment as well as smaller carpet cleaners. There
are several considerations with the use of both of these pieces of equipment: clean flooring
according to manufacturer recommendations, keep equipment in good operating condition, and
train every employee responsible for the use of the equipment and care of the floor.
We clean by zones in conjunction with the air conditioning zones and leave the air conditioning
operating overnight. We also use carpet fans in addition to the heating, ventilation and air
conditioning (HVAC) systems. If warranted, we place portable dehumidifiers in strategic areas.
If there is a breakdown in any one of these processes and the floor stays wet for 12 hours to 24
hours, the flooring may need to be replaced.
Heating, Ventilation and Air Conditioning (HVAC) Units
Q: How do you deal with the fresh air requirement in humid climates without overloading your
HVAC system?
A: The most common approach in humid climates is a dedicated outside air pretreatment unit
with separate time-of-day scheduling capabilities that allow for the conditioning of outside air
independent from the unit that supplies air to the occupied space.
Q: When running the HVAC unit on auto, do you also monitor carbon dioxide (CO2) levels?
2

-------
A: Yes. CO2 is typically only monitored when there is a demand-controlled ventilation sequence
that automatically modulates the volume of fresh air being introduced into the building based on
concentration of C02.
Q: Does the auto setting on the thermostat create a problem with limiting outdoor air and elevated
CO2 levels?
A: For systems that cycle off and on based on room temperature alone, there is a possibility that
the ventilation will be compromised. Appropriate measures are needed to make sure adequate
outside air is introduced during occupied hours across all outdoor temperature ranges.
Q: Do you think that cleaning the ventilation system (i.e., ducts) should be a higher priority than
simply cleaning the registers, return grilles and outside air intakes?
A: If the air devices look clean but the ducts are dirty, then the air system is not truly clean; all
components should be cleaned as they are of equal importance.
Temperature
Q: Should air conditioning units be running during the summer — when there are high humidity
levels and high temperatures — when school is not in session?
A: In the summer, buildings left completely uncontrolled can have many problems such as
sagging ceiling tiles and microbial growth on books, carpets and other porous materials.
Temperature setbacks are recommended for energy conservation, but relative humidity should be
monitored and controlled to not exceed 59 percent.
Q: Does the temperature of a room in any way affect the humidity of the room?
A: There is a non-linear correlation between temperature and humidity. In general, as the
temperature falls, the relative humidity rises. As the temperature rises, the relative humidity falls
for a given fixed indoor air volume. A room can feel uncomfortable due to elevated relative
humidity at any temperature, so just making a room colder can lead to that clammy feeling
unless proper dehumidification is achieved. Temperatures in schools should be maintained
between 70 and 74 degrees Fahrenheit and between 30 percent minimum and 59 percent
maximum relative humidity during all occupied hours.
3

-------