Detecting Moisture
Since a thermal imager measures temperature, how does it detect the
presence of moisture? The simple answer is, “It doesn’t.” However, in many
cases, when wallboard or other structural elements of buildings are wet, there
is evaporative cooling. As a result, wet building components appear cooler than
dry components of the same material and produce telltale cool areas on thermal
images.
Rod Hoff, a thermography instructor and thermal imager specialist
with Restoration Consultants in Sacramento, Calif., describes the process a
restoration contractor typically uses.
“When a customer has a flood situation, for example, or broken pipe,
the remediator will extract the standing water. Then the walls, ceiling, and
floors can be returned to an acceptable moisture condition,” Hoff said.
“Removing moisture from these areas requires evaporation which results in
surface moisture evaporating into the air. Due to evaporative cooling, there’s
generally going to be a lower temperature of about two to five degrees in the
wet areas.”
Hoff explains that when using the thermal imager, a contractor can
see where walls, ceilings and floors are cooler. That may be a place where
evaporative cooling is taking place. He refers to such spots as areas for
investigation.
“We’re careful not to define the problem using only the thermal
imager,” Hoff emphasizes. “We do not look through a thermal imager and say,
‘That’s moisture,’ because moisture and missing insulation may look the same on
a cold day.”
The primary tool for confirming that cool spots are the result of
evaporative cooling is a noninvasive moisture meter. Then, if necessary, they
use an invasive process using a borescope or penetrating moisture meter.
According to Hoff, moisture meter readings are generally based on the
resistance and conductivity of a material. It is effective because water
conducts electricity well.
“In fact,” Hoff warns. “One has to be careful to use a moisture meter
properly. Metal corner beads and nails also conduct well and can set off a
moisture meter.”
Saving Time and Money
Restoration contractors are reporting quick paybacks on new thermal
imagers. For example, Rusty Spearman at Acquired Home Services in Gainesville,
Va., reports his company bought a thermal imager less than a year ago, and it
has already paid for itself. In fact, the imager has provided Acquired Home
Services such a leg up against its competition, according to Spearman, that the
company plans to purchase another unit soon.
At Stanley Steemer of Ocala, Fla., John West reports that the
company’s thermal imager landed it an $850,000 contract to dry down a 600-unit
condominium following a hurricane, and a $349,000 contract the following year
for flooding in the same complex.
Water damage calls for fast responses, especially when dry downs are
an option. “Some molds and
microbes can start to grow on wet materials in just a few days,” West says. “If
we can locate the moisture and get it dried down before any growth can occur we
have saved the customer money and time.”
Consider what’s required of a restoration contractor facing
extensive flood or storm water intrusion. That contractor, Hoff points out,
faces a daunting task.
“If you have several thousand square feet of wall, ceiling and floor
and five percent of the areas are wet, but you don’t know where it’s wet, you’d
have to check all of that area with a moisture meter,” Hoff notes. “With a
thermal imager, you can quickly pan through and find the five percent that’s
wet. Once you find that five percent, you take a moisture meter and verify that
it’s moisture that’s causing the temperature differences.”
Dean Ragone of All-Risk Property Damage Experts in Summerdale, N.J.,
likes using a thermal imager because of the documentation it provides. “When we
have a large water infiltration,” he says, “we have the ability to document
conditions with the pictures, and then we just email those to the insurance
company. It makes everything so much smoother, and it’s the kind of validation
that the insurance company needs.”
After a contractor locates areas of wetness, the next step is to use
blowers, fans, desiccants, refrigerant dehumidifiers, etc., to dry down wet
areas. Of course, wet areas dry unevenly. If the only tool available to
determine what’s still wet and what’s dry is a moisture meter, there can be
“false positives” for dryness if a reading is taken between two dry areas. By
contrast, a thermal imager can reveal the wet areas.
Suppose a contractor were to walk away from a job and leave wet
spots in the walls, floors or ceilings, and the only documentation of the work
done is lists of moisture meter readings. Suppose further that, within weeks or
months, mold appears in a “restored” area. What defense would the contractor
have given the possibility of false positives?
By contrast, if the contractor had used a thermal imager, there
would be documentation of a thoroughly dry structure at job completion. “Having
before and after images, backed up by moisture measurements, is the best
documentation to protect yourself and provide proof to the customer that the
dry down was effective, whether the customer is a building owner or an
insurance company.” Hoff says. “Documentation is one of the biggest motivations
for using a thermal imager. If a contractor loses a law suit because of lack of
documentation, the amount of the loss probably could have paid for an imager
several times over.”
Securing a Competitive Advantage
Acquired Home Services’ Spearman estimates the number of mold
testing and remediation companies in his company’s service area at around 30,
up from only three or four just three years ago. “The competition is fierce,”
he says.
Spearman says that when a potential customer calls Acquired Home
Services’ office, company president John Taylor first asks whether any of the
other companies they have talked with use thermal imaging.
“Usually, people say, ‘No, what’s that?’” Spearman
said. “John explains to them exactly what the imager can do and how it’s used.
Nine out of ten times the people will go with us for testing because we have
that imager.”
Doing IR Detective Work
Dean Ragone at All-Risk refers to the use of the company’s thermal
imager for finding water in structures as forensic thermography. His company
actually invoices for thermal imaging using that description, and it is an apt
designation. In many cases thermography has discovered problems that otherwise
would have been overlooked.
Jason Redding of Horizon Restoration cites one such example.
Following an eight-unit apartment fire, the original scope of work issued by
the governing authority did not include removal of the drywall ceiling in one
of the lower units. Chris Rossi, one of Horizon’s certified technicians,
decided to check the ceiling of the lower unit. IR images showed temperature
differences in the ceiling, probably due to wetness.
“Using the IR photos and subsequent testing with
moisture meters, we were able to professionally demonstrate to the insurance
company that the ceiling was wet and had to be removed,” Redding says. “The
owner of the building subsequently issued a change order for the removal of the
drywall ceiling in that unit.”
Spearman provides another example of detective work performed using
a thermal imager. A theater room in the finished basement of a
7,000-square-foot home had mold on its walls, discovered by the owners upon
their return from a month-long vacation. The IAQ expert scanned the walls, used
borescopes in the wall cavities and took moisture meter readings. “Everything
was bone dry,” Spearman says. “The relative humidity was a little bit high,
which really concerned me because the air conditioner was on.”
Finally, Spearman scanned the floor, which was covered by a
tight-weave carpet. The imager
revealed a cool spot on the carpet—large, in the middle of the room, but
running diagonally across the carpet. “As it turns out,” Spearman reports, “one
of the water pipes going into this house went underneath the slab, and it had
ruptured. It was coming up through a minute crack in the concrete. The wetness
was invisible to the naked eye, but it was clearly visible to the imager. It
would probably still be a mystery if it had not been for the imager.”
