Moisture is the single most important factor which affects the quality of wood and many other building materials. If moisture is left undetected, it will ultimately cause major problems such as, severe structural damage, dry rot and mold. The only definite way to determine is excess or hidden moisture is present is to use a moisture meter.

Being educated on the types of moisture meters on the market, how they work and what information they provide is crucial to your success as a specialist. There are two types of technologies available, electrical resistance technology and capacitance technology. Electrical resistance technology requires the operator to penetrate the material being tested. The conductivity of the material between the points of contact, which is influenced by the presence of moisture is measured and displayed by the meter.

Pin-less meters, on the other hand, use capacitance technology to detect moisture. The sensor pad, which makes surface contact with the material being tested, sends a radio frequency signal into the material.

Which meter should I use?

A pin-less moisture meter is an excellent tool because it can scan the surface and determine if moisture is present, however it is important to remember if moisture is detected, the signal weakens as it moves further away from the sensor, limiting this meters ability to locate the source of moisture. For example, if moisture is present in insulation behind sheetrock, a pin-less meter cannot detect it. This in mind, it often becomes necessary to use a pin-less meter for a quick, overall evaluation of the job-site, and then use a pin-type meter to locate hidden moisture.

Pin type meters are capable of detecting precisely where moisture is coming from by being able to penetrate through the surface at different depths. While some people are concerned about making holes in the material, this limited damage is a non-issue considering the excess damage that could occur if this moisture were left undetected.

Pin type meters also have various accessories that can be attached to provide further information about moisture conditions in hidden areas. So, the question becomes, “which meter should I use?” Many professionals recommend using both types of meters for the best overall detection and evaluation of moisture conditions. Ideally, using a pin and pin-less meter together will give you the fastest and most accurate results. If you are currently not using a meter at all, the meter that will give the most information on hidden moisture would be a pin-type meter.


Here are some accessories that can be used with a pin type meter, making them even more useful for checking materials such as studs, insulation behind drywall, sub floors, behind baseboard mold and trim, in books or documents, and behind ceilings. The list goes on. Most of these attachments have insulated probes or blades with exposed tips, allowing the end-user to penetrate different depths only picking up moisture at the exposed tips.

Slide Hammer – The contact pins on the slide hammer have insulated shanks so that only the tips are exposed.  The pins make contact with the material at their uncoated tip and provide much more accurate readings of moisture content at various levels of penetration.  This feature allows you to penetrate through flooring to a concrete or plywood sub floor.

Deep Wall Probe – Features 4″ insulated pins for use on insulation or any tests where deeper penetration is required. This probe is also an effective tool for checking EIFS clad structures.

Blade-type Electrode – Two 5” long blades, bent to a 35° angle PTFE coated w/ exposed tips to check behind trim and baseboard molding. This type of electrode is also a great tool for checking moisture in books and documents.

What’s next in Moisture Meters?

Manufacturers of moisture meters and thermo-hygrometers are constantly looking for ways to improve products that provide information which the specialist needs to make good drying decisions. This information is ultimately brought to the customer, instilling confidence that their home or work place is a healthy, safe environment.

As the awareness and education continues, look for manufacturers to make continued improvements to their assortment of meters. These products will be feature rich, user friendly, and have the ability to capture and record key data.


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For home inspection services in the Sacramento and Bay Area please contact Golden State Home Inspections at 800.441.0804 or visit

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