The detection of moisture intrusion into the building is probably the most common thing we do as home inspectors. For this reason, the meters which are used to find moisture penetration are fairly sophisticated, and expensive.

There are two basic types of moisture meter. The first is an electric resistance meter. This meter has two steel pins which are driven into the test material. The electrical resistance between the pins is measured and interpreted to give a % water content.

The second type of meter is a radio frequency scanning meter. This type of meter is non-destructive. Surfaces can be scanned using this meter to fin damp or wet areas. The meter reads approximately .5 inches into the surface, and gives a  % water content. These meters can be fooled by the presence of metal in the underlying material. For this reason, the pin type meter is often used to provide conclusive proof that moisture is present where the scanning meter indicates. On some surfaces, such as ceramic, the pin style meter cannot be used.