There are many claims in the flooring world related to moisture testing. Can you trust what is being purported? Is there any difference in the type and brand of moisture meters?
A few years ago, on a wood flooring inspection, I observed different moisture readings from two different brands of moisture meters testing the same area.
Is this typical? Or is one more accurate?
Take a further look at the technology and find answers to these questions.
How do moisture meters work?
There are two basic types of electronic devices on the market for measuring moisture in wood: pin-type and pinless (surface meter). A third type measures relative humidity (RH) in concrete and is a separate discussion.
Technically, these meters do not actually measure moisture. The pinless or surface meter uses a flat sensor pad to measure electromagnetic frequency of the returning waves from those transmitted. Pin meters measure electrical resistance between two conductive pins inserted into the wood.
So how do these qualify as testing moisture?
The answer is gravimetry.
Gravimetric testing determines the gravity or weight of water in a material by separating out the water. The electronic meter uses this data to measure the moisture equivalence.
Do all brands of moisture meters use this technology as a baseline?
Surface meters can measure up to 3/4″ into the flooring, depending on the meter’s design. Pin meters with an extension attachment can measure up to several inches.
The big question is, “Which one is better?”
Both a pin and pinless meter have their place in an installer’s toolkit. Hardwood flooring should never be installed before checking the moisture content.
A surface meter is ideal for this as it can quickly test a number of boards without causing any pin hole damage. If there is a spike on the readout of the meter, a more precise pin meter can be used to determine the extent of moisture penetration into the wood and or subfloor (if already nailed down). Surface meters are great for fast and easy, “general” checks, but if not on the correct settings, can lead to incorrect readings.
The best meters are designed to be programmed for a variety of species and their individual gravity. The more precise the species setting, the more accurate the results.
In the earlier example, two meters had given two different readings. The surface meter showed high moisture, but when the pin meter was used in the same location at 1/2″ to 3/4″ depth, the moisture reading was within normal range.
In this case the high moisture reading from the surface meter was just that, on the surface. This issue was found to be excessive humidity levels in the home, which a simple thermo-hygrometer was able to detect. A hygrometer is a simple but very useful tool when used in conjunction with moisture meters.
So, is there a difference in the moisture readings from different brands of meters?
Accuracy of test results vary, based on these factors:
Pin-less/Surface Meters
- Setting to correct species
- Proper factory calibration
- Well charged batteries
- Sensor must be flat against surface
- Correct setting on dual-depth meters
- Correct down-pressure applied during testing
- Extreme temperature of wood can alter reading
Pin Meters
- Setting to correct species
- Proper factory calibration
- Well charged batteries
- Undamaged pins, especially if insulated
- Correct settings when using attachment electrode
- Align pins with the grain, not across the grain
- Extreme temperature of wood can alter reading
Moisture meters and hygrometers are effective and essential for every flooring professional. Using them properly will instill confidence in everyone involved – from builder to homeowner – that moisture issues are to be taken care of before installation.
Use Your Moisture Meter to Prep Your Subfloor
Moisture testing isn’t just something to do with the flooring, it’s also an important part of prepping a subfloor for installation. Find out the best way to prep a subfloor and how to use a moisture meter to take readings on our subfloor prep guide.