When determining if a structure has subterranean termites or whether there is a potential for subterranean termite infestation, moisture meters are commonly used. Moisture meters provide a moisture reading of building materials so that the inspector can determine if there are conditions which might lead to termite infestation. Subterranean termites thrive in conditions where the moisture level in the building material exceeds that of the levels commonly found in these materials. Elevated moisture levels can be from leaks, condensation, or from termites bringing the moisture with them to the feeding and infestation site. Dried wood is typically about 12% moisture; levels in the 20 plus range can lead to decay. Termites can prosper in wood from as low as 12% to well over 20% but uncharacteristically high levels of moisture may mean a hidden infestation.
There are several types of moisture meters, but the two most common are the pin and the pad moisture meet. A pin type moisture meter is a digital or gauge type of meter which has two sharp pins protruding from the unit. The pins are placed into the substrate to be tested and the reading registers on the gauge. The reading is quick and accurate and the price of the unit is reasonable (less than $200 typically). The disadvantage is that the unit only works with wood and not other building materials and is a surface reading only. It can also leave marks on the surface of the substrate tested.
The pad type of moisture meter is about twice the price of the pin type. The unit has a pad on the back of the unit and the unit is placed on the substrate. Multiple types of materials can be tested including masonry and concrete to see if there is a moisture leak which might soak into wood. There is no damage to the material being tested.
A moisture meter is a valuable tool and some states require that moisture readings be taken as part of an inspection.