How do home inspectors measure for moisture – and how SHOULD they measure for moisture?
The most prevalent but least accurate way home inspectors measure moisture is through a moisture meter. Essentially, this meter measures SURFACE moisture. This is the quick and easy method used by most home inspectors to measure moisture inside a home. Please note: If utilized to measure moisture on the surface of a foundation wall, the moisture meter must be used in conjunction with a complicated mathematical formula that is usually beyond the expertise of most home inspectors.
The second way to measure moisture is with the same moisture meter, but using a ½ or ¾ inch probe to check inside walls or floors. While this probe can identify moisture issues in the substrate material, the probes only go so deep. As a result, moisture issues can be present deep inside the wall cavity without this probe showing elevated moisture levels.
The third way to measure moisture is with a deep wall probe.
Most home inspectors never use a deep wall probe, even if they identify potential moisture issues. This probe can be used to measure moisture deep inside interior and exterior walls and provides a more accurate assessment of water intrusion than the surface moisture meter. A deep wall probe can also be used to measure moisture inside stucco and stucco-like material called EIFS that has been known to result in moisture issues and rotting.
If water penetrates these exterior surfaces, your home could be rotting from the inside out – without your even knowing it – until a major, expensive repair is required. After conducting a thorough inspection and checking for potential moisture intrusion through the foundation walls, an experienced, highly-trained inspector may also use the deep wall probe to check the wall plate in areas of potential water intrusion.
Before hiring a home inspector, ask if he or she will be using a moisture meter, a moisture meter with probes, or a deep wall probe to measure moisture within the home. Also ask if your inspector will measure moisture inside the wall plate – where and why. Asking these questions will tell you a lot about your home inspector, his or her level of training, and overall quality of inspections.
Knowledge is power!