In the arsenal of high tech equipment available to home inspectors, electronic moisture meters remain highly reliable tools in the quest to detect moisture penetration.
However, it wasn’t too long ago when many home inspectors shunned the technology. By their reasoning, utilizing moisture meters exceeded the standards of practice and thus increased liability – the perceived risk exceeded the potential benefit. But that was then and this is now. In our technological age, I suspect that very few home inspectors would venture into a home without a high quality moisture metering device even though its use still remains outside the scope of practice.
The application of this technology is fairly straightforward: First there are non-invasive devices which can detect hidden moisture without damaging the finished surfaces that may be concealing the moisture. Second there are pin type models which detect moisture after sticking pins from the instrument through the finished surface to the substrate being tested. Finally, there are instruments which perform both functions.
Depending upon the sophistication of the tool and whether testing is invasive, or non- invasive, moisture meters may be able to detect hidden moisture anywhere from depths of about ¼ inch to more than 4 inches beneath the finished surface. Obviously, an inspector must use their discretion with regard to the testing method as one cannot simply poke holes in finished surfaces.
That being said, it is important to understand the limitations of the technology: A moisture meter cannot detect rot, mold, insects, insect damage, heat loss and so on. It can only detect moisture. Certainly moisture is the precursor of rot, mold and many insect infestations, but lacking other evidence, hidden moisture alone does not necessarily mean such conditions are present – at least not yet. The meter, by itself, cannot identify what the source of the moisture is; it can only indicate the presence of moisture. A professional inspector will try to identify the moisture source, but their success will depend upon the equipment they use as well as their training, experience and expertise. Much of this goes back to being able to discern false readings from actual readings and one’s skill at using specific forensic inspection procedures to track the moisture trail. In the end, destructive discovery performed by a contractor may be the only, “proof positive”, way to determine where hidden moisture may be coming from.
Remember that a moisture meter is not a silver bullet. It is not a tool to be used randomly like some sort of sci-fi scanner, but rather a device designed for use with a specific direction and purpose and in a specific way. Residentially, this will commonly include testing suspect water stained surfaces and areas where hidden moisture is
likely to be present such as under the finished flooring by the toilet, tub, or dishwasher and behind tiled tub and shower surrounds.
If you are in the process of looking for a home inspector, having a clear understanding about what they will and will not be doing is critical. During your interviews, be sure to ask each inspector if they will be using a moisture meter as well as how and where they will be using it. The day of the inspection will be too late to discover your inspector lacks this most important inspection tool.
Larry owns and operates Cameo Home Inspection Services and is a former home inspector instructor. He can be reached at 360-459-1632