The worst question about a professional moisture meter is the unasked one.
And no matter how long you've used a commercial-grade meter, there's always the chance that you'll have a new question about how the device works or some or what you'll encounter while inspecting for moisture.
To that end, we've rounded up the top FAQs – such as "how to use a moisture meter " – we field regularly.
Here are the most common questions we get when it comes to using a professional moisture meter: (click each question to jump to its answer)
A base-level question, but a great starting point. We'll tackle this one by meter type:
A pin-type moisture meter works by using electrical resistance to measure the moisture content of a material.
When the meter's pins (electrodes) make contact with the surface of the material being tested, they complete an electrical circuit. The meter then sends a small electrical current through the material between the two pins. The electrical current encounters resistance from the material's molecules, which varies depending on the material's moisture content.
In simplest terms: as water is conductive, the less resistance, the higher moisture readings are.
Pinless (or non-invasive) moisture meter uses radio frequencies that penetrate the material being tested within its depth of measurement. The waves cause the material's molecules to vibrate and produce a secondary electromagnetic field that is detected by the meter.
The strength of the secondary field is proportional to the amount of moisture present in the material, allowing the meter to identify areas where moisture concentration is higher.
Pinless meters serve a few purposes, allowing for:
Keep in mind, a non-invasive meter's readings are qualitative and require further investigation with a pin-type meter to confirm moisture presence.
Another base-level question, but a good one.
Let's break this down by meter type again.
Giving readings for actual moisture content, pin-type meters take measurements by direct contact with a material.
To take a reading, simply touch the meter's probes to the material being tested and wait a few seconds for the device to display a measurement.
The #1 thing about taking pin-type meter readings: Do not jam the pins into the material you're testing. Not only does that potentially damage the probes, but it also increases the chances of an erroneous reading.
Measuring for moisture presence, pinless meters using radio frequencies to determine a high likelihood for moisture within its depth of measurement.
To take a reading, place the meter to the surface of the area being tested and allow a few seconds for a reading.
Non-penetrating meter readings do not give 100% confirmation of moisture. Rather, they help you hone in on areas that should be investigated further.
An important part of meter maintenance to ensure accurate measurements, calibration is a quick and easy process. It should be done at least every six months.
Again, let's look at this by meter type.
A process that also takes a few seconds, you'll need a calibration device – a moisture content standard (MCS) – designed specifically for your meter to measure resistance. Most pin-type meters come with one.
To check the calibration of your pin-type meter, touch its pins to the contact points on the MCS and wait a few seconds. Your meter should display a reading for a wood moisture equivalency of +/- 18.3% (in Protimeter instruments).
If your reading is outside that range, there’s likely an issue affecting your meter’s ability to take accurate measurements.
For this, you'll need a sensor calibration block, which is a solid, small box the meter will make contact with, that's designed for your specific meter.
After you’ve turned the meter on, place the meter to the block. You should see a reading of 999 after a few seconds. When holding the meter in the air and taking a reading, it should display a reading of 0% or three dashes.
If you don't have a calibration block, your hand will do just fine.
No matter the meter type you're using, it's always a good idea to verify it's functioning properly after calibration. Like calibration, verification is simple.
To check, take measurements with your meter and compare them against readings from a second, identical meter testing the same materials or spots. As long as the readings are identical, your meter is calibrated and ready to tackle a home moisture inspection.
An interesting question, to be sure.
In short, no.
However, a moisture meter – both pinless and pin type – is helpful in identifying where mold can be. Mold loves moisture and thrives in its presence. Using a moisture meter, you can zero in on areas to investigate where mold has already made a home or is likely to.
Yes! But only a pinless meter can because it uses radio frequencies to measure beneath the surface of the area being surveyed.
And again, be mindful of the type of reading you'll get – it's qualitative and would require further investigation to confirm moisture presence.
A professional moisture meter is indeed an investment. They can run several hundred to even several thousand dollars – a far cry from the $20 meters a homeowner might buy to have in their toolbox.
But an investment in a professional-grade meter shouldn't be looked at through solely the lens of money. Why? Because you're also investing in a few other important things:
Because moisture normally has a gradient from high to low, you should survey the area carefully and look for changes with a pinless meter. If you are getting consistently high readings, this could be caused by metal below the surface.
Always confirm the presence of excessive moisture with a pin-type meter or deep wall probes.
Typical behind-the-surface metals include corner beading and metal tile lathing.
This is typical of a condensation problem. Condensation is one of the major causes of moisture problems in buildings and is typically a surface moisture problem.
Non-invasive measurements give an average reading across the depth of measurement (up to ¾”), and pins give the highest reading for the depth of measurement (surface).
In the case of surface condensation, non-invasive mode will only show a slight increase in readings, and the pins will read high.
This is typical of a temperature condition that is outside of the calibrated range. Refer to your instrument’s instruction manual.
To maximize the life of the electrode, and stop them from snapping, ensure that you drive the probes in straight, and most importantly, use the slide hammer action to drive the probes out straight.
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