Healthy
Homes Grantee Conference Call
Mold and
Moisture Issues
Summary
Notes
December
20, 2002, 1:00 pm EST
There were 32 lines on the
call. A list of participants who
registered to participate on the conference call is included as an attachment
at the end of the notes.
Ellen Tohn served as moderator for
this call. She described the purpose of
the call and explained that the goal is to provide Healthy Homes grantees and
partners with access to technical experts on issues of interest to grantees,
and allow grantees to interact with each other.
Ellen Taylor, from HUD’s Office of
Healthy Homes and Lead Hazard Control, then welcomed everyone to this first call
of the series. She invited the
participants to provide feedback on the call as part of a larger information
dissemination and networking strategy.
The current plan is for the calls to be bi-monthly events, with
potential future topics including asthma triggers, carpeting/flooring,
community capacity building, and other tools for long-term implementation.
Related activities include:
$ Holding satellite conferences
about two times per year.
$ Encouraging use of the Healthy
Homes Grantee Electronic Exchange. The
Exchange is an interactive tool for grantees to communicate and share
information. (Bi-weekly updates on what
is on the Exchange are currently being sent out, and participants should
contact Sonya Ravindranath (Sravindranath@icfconsulting.com)
if they are not receiving them or have questions.)
$ Forming working groups amongst
the grantees on topics ranging from asthma to training to moisture
control. The conference calls will help
form the working groups and inform the topics to be addressed.
$ Sharing ongoing conference
activity. Participants are encouraged
to alert HUD about interesting conferences they plan on attending.
Background About Speaker
Ellen Tohn introduced Terry Brennan, who served as the technical expert for the call. Terry owns a small company, Camroden Associates, that provides forensic, analysis, research and training services to the building community, the research community, the public health community and owners and occupants of buildings. Recent work includes healthy building training with Joe Lstiburek of Building Science Corporation for the Boston Region HUD Healthy Homes project; analysis of fungal dynamics in crawlspace homes in North Carolina for AEC’s Crawlspace Characterization Pilot Study of sealed and vented crawlspaces; teaching four moisture and mold workshops in the Pacific Northwest for Washington State University and the University of Alaska.
Terry presented his thoughts regarding mold and moisture
issues to the call participants and responded to participant questions. The discussion focused on three topics:
Prevention
Terry emphasized that the key to
prevention is to keep building materials dry,
particularly those vulnerable to mold.
He presented four levels of material vulnerability to mold.
$ The
most vulnerable materials are those that contain starches or sugars, such as
paper covered products, like gypsum, and suspendable ceiling tiles (dropped
ceilings). (An indication that these
materials are vulnerable is that one drop of water every 12 minutes could
produce visible mold in two days.)
$ The
next level of vulnerability includes materials that produce mold when exposed
to humidity levels of approximately 95%, such as medium density particle-board
and fiberboard.
$ Sapwood
and hardwood lumbers are relatively mold resistant.
$ The
most resistant materials are porcelain, ceramic tile, PVC, and rubbers.
$ There
is a new gypsum board covered with fiberglass (such as “Dens Guard” by Georgia
Pacific http://www.gp.com/gypsum/index2.html
) which appears to be good at resisting mold growth.
In places where keeping the
material dry is impossible, use resistant materials that are easy to clean. For example, mold cannot grow on porcelain,
but it can grow on dust on porcelain. A
common example is the backside of toilets: paper fiber sticks there when the
surface is wet, and mold can grow.
Terry stated that the two worst
mold growth situations are:
$ A
big flood in a home that makes everything wet.
$ A
small, hidden leak that humidifies a cavity over time.
The hidden leak is potentially the
most dangerous, because it is difficult to detect. To combat mold growth in hidden spaces, Terry suggested:
$ Install
plumbing where it is visible to the greatest extent possible. He noted that a vulnerable area is the trap
under sinks. He estimated that 3 in 50
sinks have leaking traps, with enough moisture to grow mold.
$ Avoid
placing pipes in insulated walls and ceilings.
Condensation also presents a
problem, particularly in the southeastern part of the country, but the issue is
spreading to other areas with the increased use of air conditioning. Installing air conditioning in old buildings
can damage them by fostering mold growth, often in hidden placed like behind
wallpaper. Ventilation will dry moisture
in a non-air conditioned building, but in an air-conditioned building,
intentional and accidental ventilation is wetting the building.
Assessment
When investigating mold growth Terry stated that you need to know:
$ What
is the moisture dynamic?
$ What
containment/protection is required during cleanup?
There is not a lot of research on
this subject. The best guidance available is from
These resources focus mostly on
remediation, not investigation. The
best course of action is to act prudently.
When preparing investigation
reports, you should include:
$ A
description of the moisture dynamics in the building
$ Recommendations
for intervening
$ Specific
location/square footage of mold growth
$ Recommendations
for appropriate containment and protection
In general, Terry did not
recommend taking air samples during an investigation. He stated that it is more helpful to collect building history
from a knowledgeable person, and then go look for mold in the places where the
building is likely to be getting wet.
He emphasized that it is necessary to move things around during this
type of investigation. This method
is tedious and a lot of work, but provides greater certainty than air
sampling.
To augment his ability to find
mold, Terry uses a stand microscope like those used in the printing
industry. At 100X you can see some mold
not visible with the naked eye.
Especially in buildings with high humidity, you can use this to find
Aspergillum or penicillin. Also, Terry
carries a HEPA vacuum with him and simply vacuums up anything questionable, and
notes the location.
Making holes is the best way to
get into contained places, unless there is an access panel behind the bathtub
or in the ceiling. Be prepared to
cover holes quickly as you might find a lot of mold. Only make a hole when you have reasonable belief that mold is
present in the contained area.
$ The
best method is with a hole saw because the cut can be easily replaced, and it
creates the least amount of dust.
$ The
hole should be approximately 3 inches in diameter.
$ Look
at the back of the sample removed from the surface- mold may be growing
there.
When thinking about where to put
holes, think about wet places, such as near plumbing, under windows, and in
exterior corners, particularly behind baseboards. Helpful tip: When possible, remove mop-boards and make
holes behind them. It’s usually the
wettest spot, and then less repairs are necessary.
Moisture meters can help you determine moisture levels inside a wall
cavity, which is valuable when you’re trying to decide where to make a hold or
if a hold is needed. Caution:
There is a fair amount of uncertainty in the readings provided by moisture
meters. They work by measuring the
electrical conductivity of a material, so sometimes bits of metal can appear to
be moisture. They are valuable though
because they enable you to do tracing in the field, while with sampling you
have to send materials to a lab. They
aid in identifying locations where further investigation is needed.
There are two kinds of moisture
meters.
$ Meters
with steel pins that are pushed into a material to measure its conductivity.
< Benefits-
good for both accessible surfaces, and getting deep into a material
$ Meters
with electromagnetic wave between two pads pressed against a surface.
< Benefits-
non-intrusive, can trace things quickly.
Both types are generally
calibrated for wood. The most versatile
model is the Tramex Moisture Encounter,
which has three scales- one calibrated for wood, one for plaster, one for
masonry. It can penetrate up to one
inch in depth (valuable because a surface may be dry, but there could be
moisture inside.) The cost is
approximately $300. (http://www.tramexltd.com/)
Another model is the Protimeter- it doesn’t go as deep, but
uses a combination of pins and electromagnetic radiation. The cost is approximately $500-$600. (http://www.protimeter.com/)
If you need to know moisture
content of concrete there is a specific meter for that purpose.
Most people, with some basic
training, can use moisture meters when they are provided with training. Terry noted that most people without
specialized knowledge or training should be able to use moisture meters
effectively with proper guidance and oversight. He commented that, “If someone can use a video camera
effectively, they should be able to use a moisture meter effectively.” The University of Minnesota’s website http://www.dehs.umn.edu/iaq/moisture.html
is
helpful for learning to use the Tramex device.
Terry commented that, in his view,
there is little use for commercially available mold test kits- they act
as a settling place and have too much uncertainty. Analysis in the field is best done with tape lifts and microscopes. Nothing can be said from samples alone, but
they can usually confirm what has already been found through inspection.
Responding to a question from a
participant, Terry stated that sometimes sampling is necessary because of
liability concerns, so you have to do it anyway. In that case, you need to have someone who can identify what
you’ve found with your tape lift.
Medical mycology labs may not always be appropriate (although the
Cuyahoga County grantee uses a medical lab and was satisfied with the relationship).
Terry recommended using a good indoor mycologist. He said it is difficult to know what to look for when choosing a
lab, as accreditation doesn’t tell you a lot.
Terry works with several labs and maintains an ongoing dialogue over
time in different projects. He did
recommend two labs for culture sampling:
Treatment
Terry discussed some modest
interventions that can be performed to minimize mold in an existing building:
$ Protect
exterior cladding of building:
< Put
something on the inside walls that can handle moisture leaking through
< Install
a vapor barrier on insulation
< Give
an air vent on back of claddings
$ Landscaping:
< Have
landscaping flow away from building
< Create
an underground awning- around the outside of the building dig down 20 inches-
put roofing material against foundation and in trench to keep the soil below it
dry (i.e., the Bill Rose technique)
$ Install
gutters and downspouts in arid climates
< One
inch of rainfall can cause damage to foundation- poorly managed rainwater
causes foundation problems more often than the water table
There are articles related to the
health effects of mold on Terry’s website- www.camroden.com
How do you ensure that mold spores aren’t dispersed?
Answer: The EPA,
ACGIH and NYC guidelines provide a break down for containment issues:
·
For less than 10 square feet of contamination only limited
containment is needed
·
For more than 100 square feet containment similar to lead
abatement is appropriate
·
In between, use your judgment
Terry stated that simple barriers
afford a lot of protection. The other
way is pressure management so that air flows to workspace, not out of
the workspace (i.e., negative pressurization).
Does cleaning have to extend to non-moldy surfaces (especially carpets)?
Answer: This is
difficult to judge because there’s mold everywhere. Damp wipe all hard surfaces as a precaution and HEPA vacuum other
surfaces.
What is the age distribution of affected homes?
Answer: Mold
problems are present in homes of all ages, but more in new homes/new
renovations because of widespread use of paper covered gypsum and widespread
use of air conditioning. In older
buildings, the problems are often found in the roofing and foundation.
What type of recourse is available for tenants whose landlords don’t provide mold remediation?
Answer: More
landlords are recognizing the liability issues involved in mold issues- more
and more lawyers are becoming involved.
Terry relayed a difficult type of situation in which he will find a rental apartment unit with moisture/mold on the roof. The landlord doesn’t want to replace the roof, so to fix the situation Terry is forced to clean up the mold and then replace things in such a way that it can get wet and not grow mold. The practical reality is that you can’t always correct the moisture problems first.
A variety of moisture issues did
not get addressed, but will be addressed in subsequent email communication or
conference calls. Participants
suggested the following issues as needing more attention:
< Interpretation
of samples
< Working
in rental buildings
< Issues
with facades and roofing
< Retrofitting
mechanical ventilation systems
< Rental/public
housing renovation for other purposes
< Recommendations
for affordable steps for the individual homeowner
< Renovation
of larger buildings
< How
to make the most use of a limited budget
< When
to use biocides
< When
to tear it down instead of fixing it
Gypsum board covered with fiberglass