Common Moisture Meter Mistakes
Moisture meters ensure the longevity and quality of wood flooring and other wood projects. Correctly using these tools can help you prevent moisture-related problems and make informed decisions about finishes and adhesives. However, common mistakes can compromise the accuracy of your moisture readings.
This article will guide you through the different types of moisture meters, their proper usage, and how to avoid the most common pitfalls when using these essential tools.
When to Use a Moisture Meter
When trying to diagnose or prevent moisture problems in wood flooring and other wood projects, the obvious tool to use is a wood moisture meter, and it follows that the first obvious mistake is not to use one. But there are several factors to consider when choosing the right meter and using the meter you’ve chosen.
Your choices can mean the difference between accurate moisture content (MC) reading and a potential problem down the road.
Moisture Meter Types
There are two basic types of wood moisture meters: pin-style and pinless. Read more about the top differences between a pin-style vs pinless meter.
Pin-style meters use two narrow metal probes inserted into the wood product you are testing. An electrical signal is passed between the tips of the two probes, and the resistance measurement is then interpreted into a moisture level content read on the meter. Large hammer probes can be attached to a hand meter for deeper measurements as the probes are driven in by force, or shorter pins are most commonly pushed in by hand.
As this common name suggests, a pinless meter does not use pins or probes. Instead, it uses radio or electromagnetic signals that will change characteristics depending on the moisture level in the tested wood.
So, while the meter types are fairly easy to understand, several mistakes still prevent these tools from being an asset on the job site. Some are problems that are inherent to certain meter types, but others can be easily avoided with little knowledge. What should you watch for?
Common Moisture Meter Mistakes
Not Knowing the Reading Depth
For a pinless type of meter, not knowing the meter’s reading depth is important. For example, if the meter you’ve chosen takes readings up to 1 1/2” deep, but you’re taking readings on already installed 3/4” thick flooring, the reading you get will be somewhat affected by the MC of the subfloor. Not necessarily a helpful set of moisture readings from which to make decisions.
Using Too Little Pressure
Pinless meters can produce improper readings if the correct pressure is not applied. Too little, and the air gap under the meter’s sensor can impact the reading it takes. Some lower-end meters are even skewed by the position of the user’s hand and can vary depending on the hand’s position. Applying more than three pounds of pressure for most pinless meters is unnecessary.
The obvious risk of over-stressing a pin-style meter is that pins can bend or break. Most pin-style meter manufacturers are clear that pounding or banging on the meter is not the correct way to insert the pins into a pin-style meter. Hammer probes are built to withstand more force, but even these more rugged pins can break over time, especially in hardwood applications.
Improperly Driven Pins
Pin-style meters (and even the hammer probe type) take considerable pressure to reach the proper pin depth. In softer woods, the effort exerted is often minimal. Still, when working with many hardwoods, especially some very dense tropical species, inserting the pins to depth properly can become quite a challenge – if not virtually impossible – particularly if your meter is not constructed to take that type of force.
Bent or broken pins or even cracked meter housings become more common with increased wood types density. The temptation is not completely to insert the pins, but obviously, the reading will not be taken at the correct depth. A reading taken with pins close to the surface will never accurately reflect the moisture conditions deeper in the wood.
Trying to Take a Shortcut
Because of the effort to insert pin-style meters or their tendency to bend or break, it can be tempting to shortcut the testing process. This will speed up the testing but not give any sense of the moisture conditions of the wood or wood flooring used.
When testing large quantities of wood, or multiple parcels, it can be tempting to only test a few representative boards from the edges of the bundle.
Even in acclimated wood, moisture conditions can change in areas with more restricted airflow. Handheld moisture meters, like the Orion® 930, let you “scan” lumber or wood stock to quickly gauge the moisture conditions in much of the wood. But if a representative number of boards aren’t tested, the potential for trouble will still be high.
Overlooking General Maintenance
Any meter will suffer when exposed to high temperatures, overly wet conditions, being dropped, or other circumstances that compromise the integrity of the housing and the circuitry. But even something as seemingly minor as peeling insulation on the insulated pins of hammer-style probes can skew the meter readings.
Because the signal is not restricted to a certain depth of the wood (at the tips of the probes), readings will not be precise depthwise. They may represent a composite reading of the signal along the length of the probe or simply read too shallow based on where the signal is strongest.
Pinless meters may also give skewed readings if their sensors become scratched or damaged. Lack of regular maintenance can also upset the calibration of the meter. Only the Wagner Meters Orion line of moisture meters provide an On-Demand-Calibrator to recalibrate the meter almost instantly.
Not Using the Correct Species Settings or Species Adjustment
Most moisture meters use either user-programmed species settings or species adjustment tables. A piece of oak will have different properties than Douglas fir, so different species settings would be needed for these two.
But if your meter doesn’t allow for those differences, the readings it takes will mean poor decisions about applied finishes or its readiness to be installed. Be sure you’ve read and understood the settings for your meter.
Free Download – Is a Pin or Pinless Moisture Meter Best For You?
Can a Moisture Meter Be Wrong?
A moisture meter can be an invaluable tool for advising finish and adhesive options or for avoiding moisture-related problems in a finished project. But if improperly used, a moisture meter will not do the job it is designed to do. Know your meter, follow the manufacturer’s instructions and be sure you are choosing the meter that best suits your purposes. Then you’ll easily avoid those costly mistakes.
As Sales Manager for Wagner Meters, Ron has more than 35 years of experience with instrumentation and measurement systems in different industries. In previous positions, he has served as Regional Sales Manager, Product and Projects Manager, and Sales Manager for manufacturers involved in measurement instrumentation.
Last updated on May 2nd, 2023
Hello, Would magnetic magic paint make a pinless metre do high readings?
If there is a metallic component in the paint, then it would cause high readings on both pin-type and pinless moisture meters.
The pinless moisture meter is only going off on the studs of the interior wall board of an exterior block wall? Is this likely real moisture or just it reading some sort of metal?
Kristen, the meter is not just reading the surface of course, but actually reading through the wallboard, and every time it sees a stud, the density alone of the stud being there is causing the reading to escalate, probably. Metal would have an even greater effect on the reading. With a pinless meter, you generally need an air gap behind the material that you are actually trying to measure.
Can a moisture reading be done on drywall? We had an inspector get a 100% moisture reading on a ceiling but when we opened the ceiling- it was completely dry inside. The wood and insulation was all dry. Can you tell us how/why the reader would possibly give a 100% reading? There was no metal in the ceiling and the meter was set to “wall”.
Ty, yes a moisture meter can be used on drywall but depends on the type of moisture meter. For instance, Orion moisture meters need to be set in the relative mode for non-wood materials such as drywall. What type (pin or pinless) and manufacturer of meter is it? Makes no sense to get a reading that high, ever.
Greetings. I am getting a few very isolated spots on my (already installed) hardwood floor showing moisture but dry everywhere else (using a fairly inexpensive pinless moisture meter).
I am wondering if those are possibly false positives? or if it is possible for a hardwood floor to have very small isolated moist (ie 35% moisture, which is where the meter maxes out) spots while the remainder of the board could be dry?
Let me know if you have any thoughts! Thanks!
I would contact NWFA.org to have a certified flooring inspector come out and determine what the issue is. It is possible there is something going on below the floor and an inspector would find this for you. Thank you for writing in. Best of luck!
I’m getting a discrepancy between moisture readings and I am confused. Yesterday, I had a 3rd party certified mold inspector find high moisture readings in my bathroom floor using a pinless meter. Today, the building maintenance personnel found only low moisture readings with his 5/16in pin style meter. He kept putting it to his finger to “show us how sensitive it was” before taking a reading in the floor and surrounding drywall. Ive looked up the meter he used and it has different settings for different materials. He never changed the setting between drywall and subfloor. Could he have purposely skewed the readings to benefit his company?
Unless the pin meters are a quality, calibrated pin meter, you cannot know for sure what quality of results you are getting.
Regarding the maintenance personnel meter, you really do generally need a specific setting for the material you are measuring. Putting his finger across the pins is not the way to check a meter’s viability.
NOTE: Wagner does not manufacture pin-type moisture meters.
i use a moisture meter to get general readings of moisture in different building materials.
what do you recommend as a general purpose moisture meter for this use?
If you are just trying to get ‘relative’ moisture readings (rather than absolute; I assume that is what you meant by ‘general readings’), then every Orion model has a Relative setting that you can use. I would recommend the Model 950 if you are in the Restoration or Inspection field.
For solid wood, every Orion has the capability to provide absolute Moisture Content (MC) % values. We do provide a few settings for non-solid wood-based materials to also provide absolute MC% values.