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Moisture meter reliability for detection of building leaks or moisture problems: this article explains the use and reliability of different types of moisture detection equipment to find water entry problems on buildings. We demonstrate where moisture meters work successfully and where (and why) they don't. We explain the differences between pin type moisture meters and electronic sensor moisture measuring devices.
Our page top photo shows our client pointing to flood lines on a heating system expansion tank, indicating that this building was subject to severe deep flooding. We learned from neighbors that a nearby river had flooded this home and others in its neighborhood repeatedly over the 60 year life of the building.
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Report on the Reliability of Moisture Meters to Screen Buildings for Hidden Moisture, Leaks or Mold Contamination
I am scheduling a pre-purchase home inspection and my real estate agent asked a question about moisture detection: he wants to know if the home inspector will check the moisture level in Sheetrock? - C.W., New York, NY.
Reply: ... it depends ...
Moisture meters, particularly pin-type probing moisture meters that detect moisture by sending an electrical signal between two probes inserted into a material (such as the time-tested Delmhorst™ twin-point electronic resistance moisture meter shown at left) are one of the first tools that many building inspectors purchase after a flashlight, ladder, and screwdriver.
Relying on any test instrument alone, as we discuss at GAS DETECTOR WARNINGS , is not a good substitute for a careful inspection. While using a moisture meter is a popular tool among home inspectors and building environmental inspectors or "mold investigators", and a useful one, the visual inspection of a building for leak history is much more critical than a general "check" using a moisture meter.
After all, the building could have had a history of leaks in the past, as well as hidden rot, insect damage, or mold, related to leaks or trapped moisture, but the leak spot could happen to be dry at the time of testing.
Absence of evidence of moisture when using a moisture meter in a building is not evidence of absence of a history of building leaks, and there is a long list of visual clues that readily tell the story of a building's leak history or the risk of building flooding. .
So properly a moisture meter is, in our opinion, useful principally to confirm that a leak is current.
We also find moisture meters useful, particularly radio-signal based non-probing moisture meters such the Tramex™ electronic moisture encounter, to check for hidden leaks behind ceramic tile walls in bathrooms and kitchens where probing is impossible. Our photo (above left) illustrates use of a Tramex™ moisture encounter to check for leaks into the EIFS stucco covering of a building's window sill. Details are at SIDING EIFS WALL LEAK POINTS.
And certainly "spot checks for moisture" done randomly at a building would be nonsense.
Study Comparing the Effectiveness of Moisture Detection Methods in Buildings
In a field study this author (Daniel Friedman) conducted in February 2004 we compared the effectiveness of various methods to test for moisture in the walls of a home reported to have suffered leaks from ice dams at its roof eaves.
We surveyed the inside surface of building exterior walls of the entire second floor front and rear building surfaces using the following methods:
Conclusions of Moisture Detection Equipment Study
Home buyers and home owners are right to worry about building leaks and moisture - water where we don't want it is at the top of the list of sources of building problems. If you have a particular reason to be suspicious about something be sure to let the inspector know.
Also see VISUAL PERCEPTION ERRORS - an exploration of the theory of vision and visual errors that illustrates to building inspectors that it is important to actually inspect, and to be aware of distractions that keep us from "seeing" critical clues even if we are "looking" right at them - inattentional blindness.
Watch out for "show and tell" tools that impress the client during a home inspection but are a poor substitute for doing a good job.
OPINION: Of these questionable practices, the most hilarious (and dishonest) use of thermography that we have found popular in some areas is that made by "mold inspectors" and a few mold remediation companies who claim that their IR camera is a "mold detector".
Like any good fib, there' s just enough truth in the statement to confuse things. Sure, a leak may show up under a thermographic scan, and a leak into building cavities are a high risk for mold. But what about old leaks, now dry, that launched a large mold problem?
What about air leaks that lose energy and show up on the thermographic scan, but have not led to moisture and mold contamination? [Perhaps some readers will recall the old replacement window scam that used light meters as "energy loss" meters. ]
Continue reading at MOISTURE METER ERRORS or select a topic from the More Reading links shown below.
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