What is a water damage moisture test & why is it important?

Posted by Matt Buchanan

A moisture test is a procedure used by water restoration professionals to indicate the amount of moisture intrusion or water damage a property has sustained.

Flood Damage Moisture TestWater damage restoration professionals use moisture tests to establish drying goals for the restoration work they are carrying out. They will compare moisture content conditions in the areas they are working to restore with moisture content in unaffected parts of the building to make sure their cleanup process is thorough and complete.

The signs of moisture intrusion are often hidden. Just because you can’t see or feel the moisture, however, doesn’t mean it isn’t there. Moisture intrusion can escalate the structural damages caused by flooding, and end up costing homeowners thousands of dollars in repairs.

Many real estate professionals and others in the housing industry now believe that moisture tests should be performed regularly as part of a yearly inspection, even on homes that haven’t sustained flood damage.

Moisture Tests and Wooden Structures

Water Damage Moisture TestingMoisture tests are particularly important in the structural drying and dehumidification of wooden buildings. The optimal moisture level for a wood structure is between 7 and 13 percent. A moisture level that is over 13 percent indicates the presence of moisture intrusion. Elevated moisture content in wood can lead to microbial growth, and may even cause wood to decompose.

How Are Moisture Tests Performed?

When moisture tests are performed as part of the inspection process for a home that’s being sold, a technique called exterior probe testing is used. Two small holes, approximately one inch apart and 3/16ths of an inch in diameter, are drilled through the exterior siding. Pins are driven into these holes. Electronic meters are then used to measure the electrical resistance between those pins. This data is fed into an algorithm that produces the moisture reading.

In homes that are being restored after flooding, however, interior probe moisture testing is most commonly used. Holes are punched through a wall’s interior sheetrock. Test probes are inserted six inches into the wall, and then the probe holes are sealed with a spackling compound.

Other Types of Tests That Measure Moisture Content

Several other procedures may also be used in conjunction with moisture testing to assess the risk of moisture intrusion in flood damaged homes.

• Radioscopic scanning: Radioscopic scanning doesn’t measure moisture levels per se; rather, the technique indicates areas where moisture may be present. Radioscopic scanners measure density rather than moisture. Scanner readings are not always accurate because electrical, plumbing, HVAC and other systems will also affect wall density.

Radioscopic scanners can be used on vinyl, wood and exterior insulation and finishing systems, but they cannot be used on stucco because scanners only penetrate half an inch.

• Infrared photography: Infrared photography will reveal temperature differentials that exist in walls, roofs and ceilings. While temperature variances often correlate with moisture levels, that correlation is far from exact. In fact, most professionals say infrared photography will only pinpoint 25 percent of existing moisture issues.


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About Matt Buchanan

I grew up in Irving, TX and left for Nashville, TN for college. After college I lived in Washington, DC and then in Cairo, Egypt. After coming back to the states, I spent a couple of years back in Dallas before moving with my wife to Denver!
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2 Responses to What is a water damage moisture test & why is it important?

  1. cool I didn’t know that there was a way to check for moisture like that.

  2. Pingback: Moisture tests | Bigicedesign

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