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November 16, 2023 | Posted by MICRO
Looking to add a moisture meter to your tool bag? Here’s what you need to know to find the right tool for you.
Moisture meters come in two varieties: pin and pinless. A pin moisture meter can provide quantifiable results but needs to pierce the surface to take measurements; a pinless moisture meter is faster and non-destructive, but only provides a relative reading.
Pin Moisture Meters
Pin moisture measurement requires the physical insertion of the two pin probes into the wall (or material in question). Then an electrical current is run between the two probes, and the material’s moisture content is determined by measuring the resistance the current encounters. Water, with its dissolved salts and impurities, conducts electricity while building materials such as wood do not, meaning dry walls and floors offer more resistance. The wetter the material, the more conductive it is.
Because pin meters are sensitive to temperature and the type of material being measured, a good meter should come with options to compensate for the temperature and material encountered. The FLIR MR55, for instance, comes with a built-in library of 11 different material groups and automatically compensates for ambient temperature.
The takeaway: pin moisture meters provide you with a quantifiable measurement of the percentage of moisture in a material, but require some damage to the material being measured.
The advantage of pinless moisture meters is they won’t damage your walls—but there’s a catch. A pinless meter is a “relative” or unitless measurement device. Unlike a pin moisture meter that measures resistance, the pinless meter measures an electrical property of the material called relative permittivity.
To fully understand this measurement, it needs to be compared to a known dry sample of the same material. The best way to use a pinless meter is to make a measurement of a material of a known dryness, then make a measurement of an item of the same material, thickness, and construction.
Any rise in reading indicates moisture, or the presence of some other conductor or high permittivity material (a metal stud behind the wall, for instance, would produce high readings). Because of this, taking multiple measurements over the suspected area is highly recommended.
Pinless moisture meters may have a flat sensor that needs to be placed flush against the surface of the material like the Tramex MEX5, a non-destructive moisture and humidity meter, ideal for surveying moisture and humidity conditions if building structures.
If you think you need both a pin and pinless moisture meter for your work, then the Protimeter Surveymaster BLD5365 provides both an integrated pinless sensor and an external pin probe.