Hardwood Floors August/September 2019

than wood itself. When using a pin-type meter to test these products, depending on where the pins lie within the specimen, the electrical resistance can be less than that of dry wood. This means your moisture readings could be higher than the actual MC of the flooring sample. Fortunately, most moisture meter manufacturers have conducted a multitude of tests and can guide you through proper use of their meter when testing a variety of wood flooring products. Check with your meter manufacturer for testing protocol and appropriate species correction values when testing any engineered wood flooring product. Moisture Testing the Subfloor Your moisture

necessary when testing engineered wood flooring, it is highly probable your readings are not accurate. When moisture testing engineered wood flooring, you can’t simply set your meter to test the wear-layer species and then run the same testing you would on a similar solid board. The wear-layer species may not directly coincide with the conglomeration of material being tested. All of the materials within the depth of signal penetration can influence the readings the meter is taking. This can include the core and backing components (different species or composite materials), adhesives, and even substrate composition, which can all have different densities, specific gravities (pinless), or electrical resistances (pin-type). This will affect the accuracy of the end reading you are looking to acquire. A pinless meter will take into account all of the material it is affected by within the depth of the scanning range it can receive. When testing engineered wood flooring using a pinless meter, you will need to know the specific gravity of the entire piece of flooring itself. Check with your meter manufacturer to determine what setting it recommends for the flooring being tested. One useful method you can use to find an approximate specific gravity of the material is by the floatation method. The floatation method is a rapid method of determining the specific gravity of a piece of wood, although it is not extremely accurate, and the results of this test can be scrutinized. This test involves placing a board on end in a narrow vessel of water. The percentage of the total length of the board that is below the water line is numerically equal to the specific gravity of the specimen. This method may get you enough useful information to be able to determine what setting to use for your pinless meter. A pin-type meter can take readings of engineered flooring, when you are physically able to place the pins directly into the wear layer, and isolate your readings to that layer of wood, then change the species correction to test the core and backing. Accuracy comes into play when either of the pins comes into contact with the adhesives and varying core materials within the construction of the engineered floor. In general, the adhesives and resins found in engineered flooring (as well as plywood and OSB) are more electrically conductive

meter will also give you a reading when you test a wood subfloor. But again, is your reading accurate? When was the last time you walked onto a jobsite, looked at the OSB subfloor, and knew whether it was made of aspen or pine, and fromwhere it was sourced? Due to the variability in thematerials used in themanufacturing processes of wood subflooring, such as the different species of woods used (southern yellow pine and aspen), the location fromwhich

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the magazine of the national wood flooring association

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