PLAYING HIDE AND SEEK WITH MOLD
-How an infrared thermographer and a mold inspector
can partner in their search for mold
Rachelle Dobbs
Dobbs Enterprises, Inc.
2945 Waumpi Trail
Maitland, FL 32751
(407) 629-4820
http://www.molddetectivesrus.com/
Greg Stockton
Stockton Infrared
Thermographic Services, Inc.
(800) AIT-SCAN
http://www.stocktoninfrared.com
Abstract
Four hurricanes hit the
State of Florida in six weeks in 2004: Charley, Frances, Ivan and Jeanne.
Charley, struck on Friday, August 13th, Frances followed three weeks
later, Ivan came ashore on September 16th and Jeanne on Sept. 26th.
Huge amounts of rain coupled with wind gusts over of 100 miles per hour caused
tremendous damage. More than one in five Florida homes suffered some sort of
damage, according to news reports. Insurance claims topped 2 million. State
officials estimate insured losses at $18 billion.
The damage from these
hurricanes provided very good conditions for water intrusion and in some cases,
mold growth. Infrared (IR) thermographers and mold inspectors can be effective
partners in quantifying damage and detecting mold, as long as both understand
the advantages and limitations of their respective fields. The expertise of
both is enhanced with microbial sampling, which scientifically establishes the
presence or absence of mold. Understanding construction, water intrusion and
mold behavior all help selecting the best location for obtaining accurate mold
levels, remediating the mold and in repairing the damage.
Keywords
Infrared, thermography,
building infrared thermography, water damage, water intrusion, water leaks,
hurricane, mold, mold detection, mold inspections, mold remediation, microbial
sampling.
Introduction
Interestingly, new homes
built since 2000 seemed to have had the most water intrusion and moisture
problems in both frequency and severity. A 2003 survey conducted by The Orlando
Sentinel newspaper and WESH-TV found that 60 percent of homes built in the Orlando area in 2001 had cracks around windows and
doors, in the foundations and in the stucco or stucco-like finishes on the
block walls.¹
Two main types of water
intrusion occurred during the hurricanes. One came from the top, and one from
the side. Leaks coming from the top came from compromised roofs when shingles
or parts of the roof were blown off and relentless rain poured into homes.
Water intrusion from the sides, soon termed “water seepage” came
mostly from concrete block walls (especially in the direct path of the
hurricanes) and from around windows that were not properly sealed or flashed.
Most water intrusion problems were caused by either improperly painted/sealed
exterior walls, by cracks in the stucco-like coating applied on the walls or by
sloppy mortar joints between the blocks. [Seepages through improperly sealed block walls happen naturally because of the capillary
action of the concrete block itself.] The combination of large amounts of rain
and high winds pounding at a 90° angle, resulted in rain water pouring into
homes by the gallon; flooding living rooms, bedrooms and kitchens, warping
walls, cabinets, wood floors and soaking carpets.
Within a few days some
victims of the 2004 Florida hurricanes noticed a musty smell. Within weeks, mold
inspectors and mold remediators were inundated with phone calls. Often, the
owners of new homes called their builders to complain about their “leaky
houses” to the point that many the builders refused to answer their
phones. A few homeowners took it upon themselves to obtain proof of water
intrusion by hiring infrared thermographers to document the location of the
moisture inside the building structure. With irrefutable proof in hand, they
felt that they could convince their builders to correct building defects. But
generally, the builders brushed off their complaints, claiming an “Act of
God”. Homeowners then turned to their insurance companies, which
categorically turned down the claims on the basis that construction defects
were not covered. When they turned to city and county governments – which had issued building permits, they
found no help since there were not provisions in the building code for
waterproofing. Since then, some cities are instituting an ordinance to force
homebuilders to waterproof homes.²
Mold is a Four-Letter Word
Mold is a
microscopic fungus known to destroy building materials and cause health
problems for many individuals. Molds help in the decomposition of dead organic
materials. Mold is truly everywhere and is essential for life on earth, however
mold can become a problem in buildings when producing spores for reproduction,
when breaking down building materials and when it grows in large quantities.
Mold only needs four things in order to grow: a surface to grow on – practically
any surface, a food source, moisture and time. Where conditions are right, mold
can begin to grow and propagate in as little as 24 to 48 hours. There is no set
standard for mold levels in buildings in the United States. The samples are
evaluated by comparing the inside air to the outside air. The inside mold spore
concentrations and species should be similar to those in the outdoor
environment. Common spore counts, such as Penicillium/Aspergillus,
Cladosporium, and Basidiospores, should be less than the outside air, and both
indoor and outdoor samples should consist primarily of the same species. Mold
spores that are rarely found outdoors, such as Stachybotrys or Chaetomium, should be nonexistent
indoors. Their presence inside – even
in relatively low numbers, is a clear indication that a mold problem exists.
To understand
the basic life cycle of mold, a simple analogy with a dandelion can be made.
Generally, dandelions have a root structure, a stalk and a seed releasing body at
their top. Similarly, mold will have a stalk-like structure with a
spore-releasing body at the end. Mold even has root-like structures, although
they act more as a digestive lattice than the benign roots of a dandelion. As
wind blows across a dandelion, it releases its seeds to propagate itself; so
too with mold – the least amount of disturbance will cause the release of
spores into the air. Some mold spores do not even need any breeze and just fall
around the mold. When airborne spores land in a suitable environment, they
start to germinate much like the seeds of a dandelion. The root-like structures
of mold, called hyphae, then emerge, anchor themselves into the substrate, and
secrete enzymes to help it rot, so that it can be absorbed. This cycle then repeats,
ad infinitum.
There are three
broad categories of mold:
Allergenic, which causes allergic or asthmatic
reactions, but does not usually
cause permanent health effects in most healthy, active people.
Pathogenic, which can cause serious health problems
in those with suppressed immune systems.
Toxic, which can cause serious health problems in everyone.
Life Cycle of Mold (See Figure 1):
1. Mold spores come into a good
environment.
2. They germinate and hyphae emerge from the
spores and they start to grow.
3. These hyphae secrete enzymes into the
substrate to help it rot so that it can be absorbed.
4. Mold creates spores for reproduction.
Figure 1) Life Cycle of Mold³
Water Intrusion and Moisture
We must differentiate
between water intrusion and moisture in relation to mold and water damage.
Water intrusion implies that the building has been compromised and water is
coming from somewhere, either from the roof, the walls, the basement or from a
mechanical or plumbing leak. Moisture inside the structure is a result of any
one or a combination of factors, i.e., a water intrusion problem, a thermal
envelope problem, a ventilation problem and/or an HVAC system problem. The
swift action of the homeowner or building owner can make a huge difference
after an event, like a hurricane. Drying out the building should be done
immediately because mold problems only compound with time. If mold has already
settled in, using powerful fans to dry structures will only spread mold spores and
cross-contaminate other areas of the building. Water vapor can increase
moisture content in the building materials, thus encouraging mold growth. The
faster the infrared thermographer performs the survey after the event, the more
accurate the assessment will be in relation to water damage. Same with the mold
inspection. The faster the mold inspector performs their assessment, the less
severe the mold contamination will be.
Infrared Thermography Cannot Be Used To Detect Mold
IR thermography can be used
to find moisture in building materials, see thermal and moisture envelope
problems that can create the right conditions for mold growth in buildings, and
to see if the active HVAC system is creating problems that can contribute to
mold growth in buildings. In extreme cases where the building materials are
deteriorated to the point where the mass of the material is affected, IR can be
used; however a very sensitive IR imager and advanced IR techniques are usually
required. Infrared thermographic surveys work well to find moisture in building
materials when there is good thermal contrast due to the evaporative cooling
effect and when temperature differentials are at their peak, but diminish as
soon as the materials dry. Read these
words and heed them: Infrared thermography cannot be used to detect mold.
Mold does not exhibit an exothermic reaction that can be seen with an infrared
camera walking around a building (See Figures 2a, 2b, 2c, 2d). Clear
thermographic images of water intrusion and moisture problems were made
possible shortly after the hurricanes, due to the moisture still being present
on building surfaces. One big advantage is that large and inaccessible areas
can be surveyed quickly and efficiently. Moisture problems in ceilings, which
are not readily accessible with hand-held moisture meters, can be readily seen
even with no stains present. Large areas of walls, windows and doors can be
well-documented with infrared images. In a report, visual and infrared images
are much more convincing than, say, “the moisture meter registered
‘red’ around the window”. The old adage “a picture is
worth a thousand words” is true.
Infrared thermographers
helped detect moisture in building materials and provided clients with a visual
record of anomalies consistent with moisture intrusion, but as the months went
by and building materials dried out, thermographic surveys were less useful and
more difficult to perform. Infrared surveys are not effective when materials
that were previously wet are dry, since there is no longer any temperature
differential to detect. Some thermographers had to resort to ‘flood
testing’ methods [wetting the walls with a water hose on the outside,
while taking thermal images inside]. One might believe that by locating
moisture, mold can be located. This is not always the case. Here are a few
scenarios that occurred shortly after the hurricanes:
Scenario 1
Water/moisture came from
the roof onto the ceiling and ran down the inside of the walls and came out
onto tile flooring. An infrared survey showed hardly any moisture on the
ceiling. The homeowners had sponged up the water/moisture right away and used
fans to dry out the wall. The building materials dried quickly before mold had
a chance to grow.
Scenario 2
Same conditions as above,
except that the homeowners had carpeting and had not used a fan. Water/moisture
in the carpet kept the environment damp for a long time and as a result the
drywall wicked up water/moisture from the carpet and stayed moist long enough
to allow mold to grow. Mold then grew on the back of the drywall and on the
baseboard. Mold was also apparent from inside the room.
Scenario 3
Water/moisture came from
the roof, ran along the side of a cathedral ceiling then down the inside of the
wall. An infrared survey showed that the ceiling was wet as well as the bottom
of the wall, but IR could not see the behind the walls, where the mold was
growing. Also, the carpet kept the drywall moist and mold was found growing
about two feet up from the bottom of the drywall.
Scenario 4
Water/moisture came from
the roof onto the ceiling only and for some reason the water/moisture was able
to pool. A water/moisture stain could be seen. An infrared survey showed that
the ceiling was wet. Damp insulation kept the environment wet and mold started
to grow on the ceiling and the blown-in insulation.
Mold detection is complex
because mold can hide in the most inconspicuous of places and its behavior is
sometimes unpredictable. Infrared thermography is a great tool to detect wet
media. However, it has limitations in mold detection, mainly:
·
If the medium was
once wet and is now dry, no anomalies will be seen even though mold might have
grown on the other side.
·
If the wet area
dried within 48 hours, the chances for mold to grow will be minimal.
·
A wet spot may
only be a wet spot. Water/moisture, taking the path of least resistance, may
end up far away from the original source and mold may therefore grow far away
from the point of the original moisture intrusion or on a surface.
Pre-existing Condition
Some of the water damage
and mold growth existed long before any hurricanes visited Florida this year.
High relative humidity (RH > 80%) is common, as are badly designed, poorly
constructed and poorly maintained buildings. Preventive/predictive maintenance
in buildings is uncommon. First, all buildings should be kept dry during the
construction process. Then, all buildings should be also be tested within a few
months after construction or major renovations to the structure, the thermal
envelope, the moisture envelope and/or the HVAC system as outlined below:
·
Measure the rate
of ventilation and pressure (positive or negative) in the building. In many
cases, damage to the building is caused by insufficient ventilation and/or an
under- or over-designed HVAC system.
·
Take mold samples
from the air and the surfaces for microbial analysis.
·
Monitor the
structural integrity by using infrared thermography.
·
Check the
structure for air and water leaks using blower-door testing and IR
thermography.
Figure 2a) Visual image with no visible
signs of mold.
Figure 2b) Infrared image with no moisture
indicated.
Figure 2c) Visual image with mold present.
Figure 2d) Infrared image with wallpaper
removed…there are still no signs of moisture.
Mold Inspectors Detect Mold
Mold inspectors deal with
the results of moisture in buildings, namely mold. They qualify and quantify
the air quality in relation to mold. It is always easier to prove a positive
– the presence of a mold problem, than to prove a negative – that
there is no mold problem. An IR survey can reveal areas with a high probability
of mold presence and narrow the search, which is a tremendous help. But even if
moisture is not detected, the thermographer cannot guarantee that mold does not
exist. Mold detection is not an exact science either. A distinction should be
made here between a mold inspector and a mold remediator. They perform two
entirely different functions. The remediator is a contractor, not a consultant,
hired to clean mold from contaminated areas (and not to spread the mold to
other parts of the building). Mold inspectors are more scientists/consultants,
hired to assess the mold damage and recommend and specify remediation. In no
instance should a remediator perform mold inspections or collect microbial
samples, as this creates a conflict of interest. These are different fields of
expertise and should be kept separate.
The way mold behaves
sometimes baffles even the best of mold inspectors. Mold inspectors are faced
with four basic scenarios when dealing with a known mold problem:
·
They know the
source of water/moisture intrusion, but do not know the location of mold.
·
They do not know
the source of water/moisture intrusion, but can see mold.
·
They do not know
either the source of water/moisture intrusion or the location of mold.
·
They know the
source of water/moisture intrusion and the location of mold.
Knowing the source of
moisture in a building can help the inspector follow the trail to the mold
colony. Infrared surveys are useful; however, sometimes no thermal signs of
moisture or leaks can be seen. In this case, the mold inspector needs to work
backwards from the visible mold to the water/moisture source, be it wet or
previously wet, and now dry. In some cases, when the homeowner is getting sick
and there are no visible signs of mold or water/moisture stains, the mold
inspector needs to do some hard detective work.
When performing
a mold survey, most mold inspectors use a moisture meter to test the walls for
moisture. Whether there are visible signs of
mold and/or moisture presence or not, the mold inspector should always collect
microbial air samples to assess air quality. If a mold colony is present behind
a wall, it releases spores into the air. These spores are like microscopic
seeds that will usually (but not always) percolate through the semi-porous
drywall into the room. With the help of a vacuum pump (See
Figure 3), a precise volume of air is pumped through a canister (See Figure 4). The spores floating in the air will stick
to a slide located inside the canister. An outside air sample is also collected
as a control (baseline) and both are sent to an accredited laboratory. Once in
the lab, the microbiologist unseals both canisters and places the slides under
a microscope for analysis. The species of mold are identified and the quantity
of mold spores established for both samples. Then the microbiologist writes his
report and shows a comparison between the mold spore levels found indoors and
outdoors. With this information, the mold inspector learns whether there is a
mold problem in a particular room. If the level of mold spores found inside the
building is greater than or different than the levels found outside the
building, the next step is to find out which exact area, wall, ceiling, or
building component is contaminated. The mold inspector must rely on the
laboratory findings, but he/she must make sure that no other unusual conditions
are present. Mold sampling is not as simple as of setting up a pump apparatus
in the middle of a room, pumping a precise volume of air into a canister,
sending it to the laboratory and VOILA–you have the results.
Figure 3) Vacuum pump apparatus to collect air samples
Figure 4) Sample canister, etc.
Figure 5) Collecting surface samples.
The following are the
factors that influence the accuracy of a mold sample:
·
For some reason,
the mold is not sporing at the time of sampling.
·
Some molds may be
present but may take a long time before they spore.
·
Some molds
require an active disturbance in order to spore.
·
A lack of air
movement may prevent mold spores from going through the wall or ceiling into
the ambient air of the room, where the sample is collected.
·
Multiple
independent sources of mold may be present.
·
Large rooms with
high cathedral ceilings can dilute the spore levels because of the large volume
of air involved.
The experienced mold
inspector keeps all the above factors in mind during his/her investigation and
when collecting mold samples. Like a detective working on a case, experience
has taught him/her that only prudence and diligence will find mold wherever it
may hide (See Figure 5). The amount of money that the building owner is willing
to pay will create its own problem because it dictates how many samples the
client is willing to purchase…the more samples that are taken, the
greater the accuracy, but the greater the cost. From homeowners to corporate
board members, the decision makers are not very well-informed consumers, often
interested only in the bottom line – how much will it cost us? The
competent inspector has to suggest an adequate number of samples without
jeopardizing accuracy, or losing the project in the bidding stage to a novice
or unscrupulous competitor.
Time is of the Essence
Immediate action should be
taken following water intrusion; first, to prevent any further water damage to
the building by covering the affected structure (with tarps) and second, to
minimize mold growth. Considering that mold can start growing within 24 to 48
hours after water intrusion, the sooner action is taken, the better. A simple
thing, like removing all wet carpet immediately will greatly reduce the chance
for mold contamination.
The proper way
to protect a building and check for water/moisture damage and mold,
specifically after an event like a hurricane is shown below:
·
The
builder owner quickly assesses the damages and contacts his insurance company.
·
The
building owner hires a contractor to protect the building from further damage
and has him remove all wet carpeting and building materials immediately.
·
The
infrared thermographer is hired to survey the building and produce a complete
report with infrared and visual images and recommendations.
·
Using
the information from the IR thermographer, the mold inspector performs four
main tasks: conduct a mold
inspection, collect mold samples, evaluate and reconcile the laboratory
findings results with the mold survey, and write a protocol (if necessary).
§
The
inspection helps document visible signs of mold-like substances and the
‘red flags’ that often lead to mold growth. The inspection, along
with the IR images obtained from the thermographer indicates the best location
for sample collection.
§
Samples
are collected and sent to an accredited laboratory for analysis to determine if
a mold problem exists based upon the species and relative amounts of mold
present.
§
Laboratory
results are evaluated to provide the client with a summary report reconciling
the laboratory results with the mold survey to identify the area(s) with a mold
problem.
§
Write
a protocol per the guidelines of the New York City Department of Health (or
similar) to describe the scope of mold remediation and outline the steps to
remove contaminated materials safely while protecting the occupants and
workers.
·
A
mold remediator will follow the safety precautions outlined in the protocol in
removing the mold-contaminated medium while preventing the emission of fungi
and dust contaminated with fungi from leaving the work area and entering an
occupied or non-abatement area.
·
48
hours after remediation is completed, the mold inspector will perform a
post-remediation sampling to determine if all remediated areas are acceptable,
both in terms of species and spores levels compared to conditions found
outdoors.
Conclusions
Infrared thermographers
must recognize the limitation of infrared surveys in mold detection. It is
always best to recommend that the client also hire an expert mold inspector. In
all types of buildings, moisture information gathered by an infrared
thermographer is extremely valuable to the mold inspector because it narrows
down the search for mold, so long as the IR survey is performed quickly after
the event. This saves the client time and money. Experts in both fields are
needed – one dealing in moisture detection and the other in mold
detection. The final objective is to help the client determine whether and
where water damage has occurred and if so, whether there is a mold problem in
the building. The cost of hiring both experts is minimal when the owner
considers the preservation of structural integrity of the building and
safeguarding the health of its occupants.
References
1.
Tracy, Dan.
“City Looks To Tighten Rules for Builders” The Orlando Sentinel,
11 Nov. 2004, final edition: sec. A: 1, 8
2.
Tracy, Dan, et
al. “Home Builders Are Told To Add Waterproofing” The Orlando
Sentinel, 12 Nov. 2004, final edition: sec. B: 3
3.
Harriman,
Brundrett & Kittler “Humidity Control Design Guide”, p.102.,
ASHRAE, American Society of Heating, Refrigerating and Air Conditioning
Engineers, Atlanta, GA., December 2001