There are two general types of moisture meters. The first uses sharp pin probes that are pushed into the material to be tested. The pin probe meter detects moisture by electrical conductivity, since wet materials conduct greater amounts of electricity than dry materials. This meter leaves pinholes in the materials being tested. The second type of meter sends an electronic signal into the material. The degree of moisture determines how the meter will register the returning signal.
Both types of moisture meters are battery operated and can be used repeatedly. The meters range in cost from about $200 to over $1,000 and can require some technical experience. For example, damp wood is measured with a different setting and scale than damp concrete or brick. Companies that specialize in fire and flood damage restoration are likely to have this equipment and be experienced in its use. If you decide to purchase or borrow a moisture meter, plan on spending some time becoming familiar with it and thoroughly reading the owner s manual and instructions. Keep in mind that hidden metals or salt deposits may falsely indicate that materials are wet when in fact they are dry.
Testing for Weathertightness
All homes are supposed to be weathertight but many are not. One simple method for testing is to literally water the house. You can specify that the exterior of the house shall be weathertight before any interior construction begins. Once the exterior is complete and the doors and windows are installed and caulked, spray the house with a hose so that every part of the house gets soaked for at least 15 minutes. Then inspect all areas inside the house for leaks. A moisture meter will be useful for this task.
This test should be performed only prior to the installation of interior sheathing or insulation so that leaks can be easily detected, dried out, and remedied. The test will be much more effective if a negative pressure can be created in the house while the test is being performed, as this will more accurately simulate pressure conditions that exist during a storm. A blower door is an excellent way to create a known negative pressure for this test. (See the section on blower doors below.)
