How to Use a Wood Moisture Meter

A lot depends on ensuring the wood is below a specific moisture level before applying any paint or stain. In addition, you will get a better and more durable finish with dry surfaces. Thus, consider learning How to Use a Wood Moisture Meter for accurate measurements.

First, check the product manual and confirm the specific gravities for your wood type.

Then, wipe any visible water from the meter and surface.

Also, adjust the moisture sensor according to the lumber species before using it on the material.

A moisture meter helps ensure the lumber stays below the recommended levels.

However, we have various product categories. So, check out this article to learn more about these devices and get the best from them.

What Is a Wood Moisture Meter

Wood moisture meterA moisture meter is an essential device that detects the moisture content in various materials.

In addition, it measures the amount of water in the wood to help determine whether it is suitable for the desired purpose.

Indicator scales on the accessories vary but will all reflect the moisture content in percentage.

Further, some moisture meters give an analog scale while others read % MC digitally.

The accuracy of meter readings and the appropriate substrate scales vary per instrument.

They also depend on the brand and type. Hence, consider your material’s nature for a successful exercise.

Moreover, most moisture meters are more suitable for wood. Thus, you can expect relatively accurate readings of lumber moisture content.

Typically, the accessory’s scale ranges between five and 40%. However, you will use a broad scale of zero to 100 when testing moisture content in non-lumber materials like concrete. Zero is bone dry, whereas 100 shows saturation.

Moisture meters have visual LED indicators related to the scale for dry, moderate, and wet or saturated readings.

In addition, they may also deliver a third scale for gypsum readings.

These scale readings range from 0.2 to 50% moisture levels. Therefore, selecting a moisture meter that accommodates gypsum scale reading for sheetrock is advisable.

Color indicators on moisture meters come in handy in determining whether the material is dry or has a potential moisture problem.

Green shows dry, yellow moderate, and red indicates high water levels. This way, you experience minimum confusion when interpreting a %MC as dry versus a moderate one.

Besides, you will know when to investigate the material when suspecting moisture problems.

Pin and pinless moisture meters give limited moisture readings, requiring you to use additional accessory probes for areas deeper than 5/16 inches.

Also, consider interesting the instrument into substrates for a more accurate depth or core detection.

A good example is Exterior Insulated Finish Systems (EIFS) testing.

Moisture problems in EIFS are usually within stucco surfaces and come from poor sealant application around door and window frames.

You can use long-insulated contact pins for deep penetrations. Then, drill holes into the surface and insert the extra-deep pins to prevent false readings.

Alternatively, consider hammer probes to give the required depth without hole drilling.

They accommodate up to 1½ inches depth readings and are excellent for core and shell tests to detect moisture gradient.

Moisture meters estimate the moisture content and assist building inspectors, hobbyists, carpenters, and other woodworkers in determining whether the material can accommodate future humidity changes.

Home and building contractors depend on these accessories to identify potential issues and damage in structures from moisture build-up.

On the other hand, woodworking industries, including furniture makers, utilize wood moisture meters to ensure quality and durable structures.

Finally, flooring contractors use these devices to determine ideal conditions for installing floors over subfloors or concrete slabs.

Types of Wood Moisture Moisture Meter

We have three common moisture meter types for inspecting various structures and building materials: Pin, pinless, and all-in-one.

They offer specialized purposes and are unique to your applications.

Pin-Type Moisture Meter

Moisture Meter In How to Use a Wood Moisture MeterThese devices have two pins and penetrate the material at the desired depth.

They measure the %MC at a depth of the contact pins and utilize the electrical resistance principle.

Pin-type moisture meters measure the conductivity between the pins and usually read up to 5/16 inches deep.

These pins have relatively sharp and uninsulated tips to penetrate the wood for a sub-surface reading. 

Although the accessories use a wood-calibrated scale, they can measure moisture content in other materials and substrates.

For instance, you can use them in drywall, painted surfaces, concrete, and ceiling tiles.

The moisture content percentages range from five to 40. However, a lower-end reading ranges between five and 12 percent, while a moderate one is between 15 to 17%. Then, the saturated or high range is usually above 17%.

A pin-type moisture meter is the most suitable for identifying the exact moisture build-up locations.

Moreover, the insulated contact pins have exposed uncoated tips to guarantee accurate readings at various penetration levels.

Most woodworkers view the above as an invasive process, despite it giving the difference between core and shell moisture content.

However, you can also get an accurate estimate by touching the pins to the material under testing.

So, it remains an effective instrument for measuring moisture levels.

Pinless Moisture Meter

The instrument is non-invasive and relies on the electrical impedance principle.

In addition, it gives a non-destructive moisture content measurement strategy in wood, gypsum, and concrete.

Scales on the moisture meter are similar to those on pin-type meters.

They read MC at five to 30% and use a zero to 100 relative scale for non-wood materials, vinyl flooring, shower tiles, and other finished surfaces.

Besides, the accessories can read up to ¾ to one inch deep into a subsurface.

Thus, they are excellent for detecting moisture build-up problems where visual cues are not evident.

All-In-One Moisture Meter

This moisture meter utilizes the above moisture content measuring strategies.

Hence, you can use them to identify water problems and pinpoint moisture build-up or damaged areas.

The instrument uses the same %MC scales for wood and non-wood materials. So, it delivers the versatility necessary for a thorough inspection.

In addition, this versatility makes the meter perfect for indoor air quality specialists, flooring specialists, home building inspectors, and general contractors.

How to Use Pin Wood Moisture Meter

Pin moisture meters utilize the electrical resistance principle to measure the moisture content in various materials. 

Further, water is a conductor, while most substrates like cotton, gypsum, wood, and hay are resistors.

Therefore, the easier electricity flows through the material, the wetter it is.

However, it is advisable to calibrate the instrument for the material under testing to deliver more accurate results.

In addition, please note that different substrates have varying inherent resistance to electrical current.

Thus, you need the device to be in the recommended setting.

Pin-type moisture meters feature two metal probes that must penetrate the lumber’s surface.

Then, electrical current flows from pin to pin and measures any resistance.

These devices take advantage of the fact that water conducts electricity while wood does not.

They use electrical resistance to determine the moisture content in the material.

Bent and broken pins are a drawback to pin-type moisture meters.

The pressure applied when pushing the probes into the material weakens them. So, evaluate the instruments regularly.

Pin wood moistures are also sensitive to temperature. But most quality devices will come with a temperature correction chart.

Thus, you won’t have to worry about the specific levels required for your device.

The meters are also vulnerable to the lumber’s chemical makeup. And since different wood species have other compounds, adjust the device to the material.

Here’s How to Use Pin Wood Moisture Meter:

How to Use Pinless Wood Moisture Meter

Pinless moisture meters utilize electromagnetic radio frequencies to test for water presence in materials.

Further, the electromagnetic wave fluctuations are perfect for determining the sample’s moisture content.

The instrument’s accuracy depends on the material’s specific gravity. This attribute measures its density compared with other materials, requiring you to calibrate the meter to the wood’s SG value.

In addition, various wood species have different densities. Hence you need to set the meter to the correct density setting before measuring the material.

Lastly, these devices measure moisture content face down to 0.25 inches or from 0.75 to 1.5 inches for deep measurements.

Here’s How to Use Pinless Moisture Meter:

Can You Use a Wood Moisture Meter On Plaster?

You can use a wood moisture meter on plaster. But it is prudent to interpret the readings as an equivalent moisture value.

For instance, if this material were lumber, it would have this moisture percentage.

In addition, the meter does not know the difference in the material. So, it assumes you are working with wood and gives a reading.

An equivalent measurement is not quantitative or accurate to the moisture in the plaster.

Thus, write the results as Wood Moisture Equivalent WME (equivalent moisture value in the plaster if this were wood). 

Building materials like timber, plaster, concrete, and brick vary dramatically in their ability to absorb or store water and capillary makeup.

Therefore, it is difficult for manufacturers to design moisture meters specifically for them.

Ideally, a surveyor would calibrate an electronic moisture meter for each material. But this process needs multiple separately calibrated devices, making it highly impractical.

As such, masonry workers use wood-calibrated meters to give moisture equivalent readings.

What Is a Good Reading On a Moisture Meter?

A 0-15% moisture reading is the standard and causes no concern.

However, measurements above 15% call for further inspections, whereas levels between 25 to 30% show water ingress and require remedial work.

Wood reaches its equilibrium moisture content (EMC) once it acclimates to its surrounding.

Besides, at this level, the moisture in the lumber balances with the environment’s relative humidity and temperature.

Further, the wood remains in the above state as long as the temperature and RH don’t change.

For instance, it will attain an EMC under eight percent when the temperature is 68F, and RH is 40%.

Moisture meters measuring water percentage in wood are most valuable when water levels range from five percent to less than 30%.

Above this range, the instrument’s accuracy is significantly lower, and the readings are no longer helpful.

Wood in buildings features a five to 15 percent moisture content. In addition, the best moisture range for interior furniture work is six to eight percent, whereas interior softwood millwork tolerates a slightly higher MC.

Finally, naturally occurring minerals or chemicals, the wood’s density, and the type of moisture meter affect the accuracy of the readings.

How Do You Calibrate a Wood Moisture Meter?

Calibrating a meter is a crucial concern when taking moisture readings. Otherwise, you will get erroneous results.

Besides, being one or two percentage points off significantly impacts your work’s quality.

Below is a simple way to calibrate your device.

  • Ensure the serial number on the On-Demand Calibrator (ODC) matches your meter’s serial number.
  • Position the ODC on its legs on a non-metallic surface.
  • Turn the meter on and use the material or species button to put it in CAL mode.
  • Position the instrument on the ODC and correctly seat its sensor pad firmly in the recessed area. This way, you avoid inaccurate calibration.
  • Move the device slightly up and down and then sideways to set it firmly.
  • Apply some downward pressure and press the audio button three times. The moisture meter will make beeping sounds to confirm the calibration process.
  • Immediately remove the device from the ODC once it displays the word LIFT. Then, hold it in the air for about five seconds until it reads DONE.
  • Lastly, press HOLD/ON to return the machine to normal measuring mode.

It is prudent to know about different methods of checking moisture meter calibration. Not all meters are the same.

Some of them have built-in calibration tests, while others do not have the feature.

Here are a few tips for testing moisture meter calibration.

  • Evaluate Pin Moisture Meter Accuracy With Moisture Content Standard

We have two primary moisture testing tool types for quantitative readings in building materials:

Pin and Pinless devices. Each device needs a different calibrating testing instrument.

For instance, pin meters use a moisture content standard (MSC) tool to check their calibration.

Position the pins on the MCS’s metal contacts and turn on the meter. Then, review and compare the reading with the given values.

The moisture meter is out of calibration when it features a different reading than the MCS.

Also, low battery causes inaccurate testing results. Therefore, try replacing the battery and repeat the test.

  • Check Pinless Moisture Meter Calibration With a Sensor Block

Pinless moisture meters operate differently from their counterparts, so they do not use the same testing instruments.

Instead of using a Moisture Content Standard, the tools utilize a sensor block.

Hold the device to the sensor block and ensure the scanning plate makes contact with the block. Then, turn the meter on and compare the reading with the sensor block’s value.

The moisture meter needs recalibration if the reading differs from the given figure. Also, it is advisable to take it to the manufacturer for correction.

  • Assess Meter Calibration With a Second Moisture Testing Tool

This technique is less accurate than using a sensor block or a moisture content standard. But it is an excellent alternative if the meter does not feature an in-built calibration check feature.

You need an identical moisture meter as a reference, which is more expensive and inefficient than purpose-built testing devices or built-in checks.

Use the second meter only for reference checks, then test with a different technique every few uses. Here’s how to check the moisture meter calibration.

  • Push the meter pins being tested to their full depth.
  • Activate the device and record the reading.
  • Insert the reference meter’s pins into the material. Use new holes close to the first pair.
  • Turn on the reference meter and compare the readings.
  • Repeat the procedure at a different testing site.

The meters have an accurate calibration when they show similar readings. Otherwise, the device is off if it is consistently higher or lower than the reference meter’s readings.

Frequently Asked Questions

Here are some of the most common questions that you will come across when discussing this subject:

  • Which Moisture Meters Work Best for Water Damaged Structures?

Pinless meters are more suitable for quickly determining wet areas on floors and walls. They can test large areas faster and tell whether you need further testing in specific locations.

Alternatively, you can consider using a pin-type moisture meter to get the exact water damage location in subfloors and behind walls.

Besides, the key to finding hidden moisture is using an electrode with insulated contact pins.

They are also read-only at their uncovered pin tips, allowing you to drive them into the surface at various depths.

  • Can I Use My Moisture Meter to Check for Pest Infestation?

A moisture meter can tell whether surfaces are safe or in danger of pest infestation. Moreover, pin-type meters are the best way to determine the exact infestation point behind walls and ceilings.

The instrument detects moisture where pests can thrive and grow without human interaction.

In addition, while mold and fundi grow in lumber with a 20% moisture content, some insect species can survive with 12%MC.

  • Are Moisture Meters Affected by Surface Moisture?

Surface moisture in the lumber does not affect pin meters about 1¼ inches or longer pins with an insulated shaft. Only short pins with uninsulated shafts are prone to surface moisture.

However, a pinless meter is susceptible to damage when the surface moisture is above a certain level.

For instance, the instrument might detect moisture measurements ranging from ten to 20% higher. But this move works best when the lumber has a small condensation amount.

Fortunately, Wagner’s IntelliSense™ technology tries to solve the problem. These moisture meters minimize the impact of slight moisture amounts on the wood’s surface.

Also, the tool measures the wood’s moisture, not the surface.

  • Can a Moisture Meter Be Wrong?

A moisture meter can give a wrong reading depending on the product type: pin or pinless, the quality, and how you use it. Further, even the best instruments can give an inaccurate result when misused.

The meter will give a wrong result when not calibrated. In addition, most devices are factory set and ready for use. Therefore, it is advisable to confirm it is set for the exercise.

Pin type moisture meters are sensitive to temperature variations, requiring you to use temperature correction charts. In addition, they are susceptible to the wood’s chemical makeup.

On the other hand, pinless meters are sensitive to wood density or ‘specific gravity.

Thus, ensure that you set them to the correct wood density before taking a moisture reading. Otherwise, the result will not be accurate.

  • What Is a Normal Moisture Reading?

Cabinets, wood objects, furniture, and other indoor woodwork require a 6 to 8% moisture reading.

But the range can extend to 10% in high humidity areas or locations near large water bodies.

Microphones, bowling pins, wood musical instruments, and other specialty items need a 6-9% moisture reading, while hardwoods work with a 6-8% range.

The moisture content in hardwood flooring should be within 2 to 4% of the subfloor moisture level. And that of wood in framing, exterior furniture, and exterior construction ranges from 12 to 19%. 

Anything above 19% is prone to mold and decay.

  • How Do I Maintain My Moisture Meter?

Generally, manufacturers calibrate moisture meters used for inspection, and they recommend the following to keep the instrument in a good working condition:

  • Store the device in a clean, dry location.
  • Keep the electrodes clean. You can use a biodegradable cleaner on external parts.
  • Change the pins and batteries when necessary. Running the meter on low batteries can cause the meter to go out of calibration.
  • Return the moisture meter to the manufacturer or service center for repairs and recalibrations.

Conclusion

It is prudent to embrace a moisture meter for your work, regardless of being a hobbyist or a professional woodworker.

The tool helps you determine whether lumber is dry enough for use. So, check out the discussion above on:

How to Use a Wood Moisture Meter

Moisture meters vary depending on the type and manufacturer. In addition, there are specific instructions to adhere to for accurate measurements. Therefore, it is prudent to always read the product guide before using the device.

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Tyron Otieno

Tyron is an avid woodworker and writer. He founded this website to help other woodworkers, whether hobbyists or professionals by sharing his knowledge and experiencie after a decade of woodworking.

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