Hardwood Floors December 2018/January 2019

Tips to Manage Your Moisture Meter AT THE SITE

It is highly recommended to perform the two tests described in addition to using the calibration check blocks.

that there is so little water in the wood that the meter has reached the limit to indicate a lower moisture level. The dry wood blocks all measurements. Some pinless meters can measure lower moisture contents than some pin meters. Next, make sure your meter is actually reading. Touch the pins with two fingers or put the measuring plates on your forearm, push the “READ” button and you should be able to get a value above 12 percent.

It may sound easy to take moisture measurements: just stick the needles in the wood, or place the meter on the board. However, there are some essential variables installers and inspectors need to be aware of, to correctly measure the moisture of a wood floor. CHECKING YOUR MOISTURE METER: You can check the primary functions of your meter by performing the following simple tests: PIN OR PINLESS: First, hold the meter in the air and take a reading with nothing touching the pins or the measuring plates. The meter should show the lowest possible measurable value. Depending on the make of the meter, the meter may indicate “LOW” or “MIN.” It is important to be aware of this low limit because your meter cannot indicate a lower moisture content.

Follow the manufacturer’s instruction. The tolerances allowed are between 0.5-1 percent. Meter, cable, hand probe, all connections and the calibration are checked with the external test blocks.

MEASURING WITH YOUR PIN MOISTURE METER: Pin meters measure the electrical resistance between 2 (or 2 plus) pins. If there is more water in the test sample, the resistance gets lower, and the meter indicates a higher moisture value. Less water and the electrical resistance gets higher; the meter indicates a lower moisture value. Measurements are obtained from the space between the pins. If pins are Teflon-coated, the meter measures moisture where the tips of the pins are placed. This is the only way to obtain core measurements, measurements from a subfloor, or moisture gradients within the entire system without removing the floor planks. THREE FACTORS AFFECT THE INDICATED MOISTURE VALUE BY A PIN METER: 1. Differences between different boards of the same wood species. Each

For a quick confirmation before testing starts, touch both pins at the same time and turn the meter on. Displayed value should be above 12 percent. Even though most meters internally check the circuitry, cable connections, cable and hand probe can only be checked externally from the tip of the pin to the display by hand or by an external calibration check block. It is also recommended to use a calibration check block provided by the meter manufacturer. You cannot check a pin and a pinless meter with the same check block. Based on the different measuring technology, two different check blocks are required. Meters from different manufacturers also use different check blocks.

All photos courtesy of Grete Heimerdinger.

Pinless meter indicates the lowest measurable value with no material behind the measuring plates. This meter shows 5.4 on setting #50 as the lowest moisture percentage. Wood can have a very low (many times non-measurable) moisture level in high desert areas such as Colorado, or in the cold winter months in places like Minnesota. The theory behind it is

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