Hardwood Floors February/March 2024

By Jeremy Waldorf

So, you’ve performed your testing according to ASTM test methods and discovered moisture (or the potential for moisture) in your substrate, but what are your options to deal with it? The answer is not always simple because there are a lot of variables, including subfloor type, installation method, and more. Of course, the most important thing you can recommend is to stop the moisture at its source whenever possible. Assuming that has been attempted, and the situation hasn’t improved, the industry has several different ways to mitigate or slow the passage of moisture, so let’s start with the simplest remedy of high moisture adhesive. unfortunately, discovered that moisture was the culprit. For some professionals, managing substrate moisture can be a mystery. Let’s unravel some of it here. Many years ago, a customer of mine called me to look at her mother’s hardwood flooring. She told me there was some serious buckling and warping, but nothing could have prepared me for what I was about to see. The solid hardwood was installed by a general contractor who did not account for moisture. As a result, this wood floor looked like the waves of Lake Michigan. In some areas, this floor buckled 10” off the floor. The force of the hardwood buckling actually broke the wall base in some places. I performed some moisture testing (applicable ASTM test methods), and

Modern adhesives can be an answer to moisture present in a substrate, especially concrete. Sometimes special trowel notches are used, or spacers are embedded in the glue to help to achieve a certain film or layer thickness during the installation process. However, certain care must be taken to understand if this application will achieve the results you’re hoping for. Some high moisture adhesives claim to control moisture, while others simply tolerate it and don’t offer protection to your hardwood flooring itself. It also is important to read the instructions and the warranty literature to make sure the concrete slab is prepared properly, does not require profiling, and the application techniques are correct before you commit to this method. High moisture adhesives generally are more expensive than standard adhesives, but could be part of your solution. When it comes to concrete substrates, true moisture mitigation often is considered the best line of defense against moisture vapor emissions coming from the slab itself. This is especially true of the older slabs where an under slab vapor barrier may not be present or has degraded due to age, or even a new concrete slab where the added moisture content, drainage, or grading, as well as environmental conditions, could contribute to the problem. Some products advertise easy application without the need for grinding or shot blasting to achieve a profile, but this can be misleading. Once again, make sure you read all the installation details, including the cleaning instructions because there are many contaminants and impurities on the surface of a concrete slab that will prevent a moisture mitigation product from doing its job properly. The process of moisture mitigation application can range from simpler to more involved, but generally, they’re all teachable if you’re willing

the magazine of the national wood flooring association

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