How to Use a Moisture Meter & Other FAQs

Pin Moisture on plaster-1

What's the worst question about a professional moisture meter?

That's easy. It's the unasked one.

And no matter how long you've used a commercial moisture meter, there's always the chance that you'll have a new question about how the device works 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.

10 Professional Moisture Meter FAQs + Their Answers

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)

  1. How does a moisture meter work?
  2. How do you use a moisture meter?
  3. How do you calibrate a digital moisture meter?
  4. Can a moisture meter detect mold?
  5. Can a moisture meter read through tile?
  6. How much does a moisture meter cost?
  7. Are non-invasive meters affected by metal? 
  8. My pin mode reads high but my non-invasive mode reads low. What’s happening?
  9. When in non-invasive mode, my meter shows a reading in air?
  10. How do I break fewer hammer needles?

How Does a Moisture Meter Work?

A base-level question, but a great starting point. We'll tackle this one by meter type:

How Does a Pin-Type Moisture Meter Work?

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.

Further Reading:


How Does a Pinless Moisture Meter Work?

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:

  1. A fast initial inspection to determine the locations of potential moisture problems
  2. Identifying moisture presence in areas otherwise impossible to check, e.g. behind tile walls, underneath laminate flooring.

Keep in mind, a non-invasive meter's readings are qualitative and require further investigation with a pin-type meter to confirm moisture presence.

How Do You Use A Moisture Meter?

Another base-level question, but a good one.

Let's break this down by meter type again.

Using a Pin-Type Meter

Protimeter Surveymaster Carpet_2Giving 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.

Using a Pinless Meter

Protimeter Reachmaster Pro-displaya-1Measuring 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.

How Do You Calibrate a Digital Moisture Meter?

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.


Calibrating a Pin-Type Meter

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.


Calibrating a Pinless Moisture Meter

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.


Can a Moisture Meter Detect Mold?

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.

Can a Moisture Meter Read Through Tile?

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.

How Much Does a Moisture Meter Cost?

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:

  • Better diagnostics – Made with sophisticated and highly reactive sensor technology, professional meters can take more precise readings.
  • Reliability – With better readings, a professional meter provides accurate, consistent, and repeatable results every time.
  • Saving time – Having accurate and reliable results means you won't have to double back after an inspection is completed to re-measure.
  • Longevity – Professional-grade moisture meters are made with high-quality components and are designed to last decades.

Are Non-Invasive Meters Affected By Metal?


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.

My Pin-Type Meter Readings Are High But My Pinless Readings Are Low. What's Happening?

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.

When in Non-Invasive Mode, My Meter Shows a Reading in Air?

This is typical of a temperature condition that is outside of the calibrated range. Refer to your instrument’s instruction manual.

How Do I Break Fewer Hammer Probe Needles?

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.


What Are The Environmental Factors That Can Affect Moisture Meter Readings? 

Environmental factors like humidity and temperature can influence moisture meter readings because they affect the moisture content of materials. Higher humidity can lead to higher moisture readings, while temperature variations might impact the electrical conductivity within materials, thus altering readings.


How Do You Interpret Varying Moisture Levels Across Different Materials or Surfaces With a Moisture Meter? 

Interpreting varying moisture levels requires understanding the baseline moisture content of different materials, as each material responds differently to moisture. Comparison with known dry conditions of the same material is essential for accurate interpretation.


Can Moisture Meters be Used on All Types of Building Materials, and How Do You Adjust The Meter for Accurate Readings on Each?

Moisture meters are versatile tools applicable to a diverse array of building materials. However, to ensure precision in your readings, tailoring the device settings to match the specific material is key. Always refer to the user manual or the manufacturer's advice for detailed guidance on adjusting your meter appropriately for different surfaces.


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