Hardwood Floors February/March 2025

AT THE SITE Unlimited Moisture Protection/No Need to Moisture Test (Continued)

The only way to learn about the moisture condition of the slab is through moisture testing. Moisture testing is a crucial step in ensuring the success of any wood floor installation. To “become aware” of what the moisture condition of the slab is, is to “understand” how to properly prepare the slab for installation, and to decide what systems to use. The issue is that learning about the moisture condition of a concrete slab takes time, money, and energy. Just as it would have taken time, money, and energy to check that the wall was not load-bearing before cutting into it. THE CHALLENGES OF MOISTURE TESTING CONCRETE To assess the moisture condition of the slab, flooring contractors rely on various testing methods, including calcium chloride tests, relative humidity in-situ tests, and electrical moisture meter tests. The calcium chloride (CaCl) test (ASTM F1869) is an invasive test that requires adequate preparation of the test area, grinded to a CSP 1-2, 24 hours prior to placing the test, then setting the test and coming back within 60 to 72 hours to measure the results. The in-situ relative humidity (RH) test (ASTM F2170) is an invasive test that requires identifying slab thickness, drilling holes in the slab to a designated depth based on that slab thickness, then placing the sleeves in the holes and letting them sit for 24 hours before taking readings. The electrical moisture meter test (ASTM F2659) is quick and easy (just like testing wood products), but has not yet been accepted through ASTM as providing quantifiable data to justify whether the moisture condition of the slab is acceptable or unacceptable for installation purposes. Each of these test methods are specific and unique in what they are testing, at the location they tested, and at the precise time of the test. Whether it’s the accuracy of the data provided by each test, or the time necessary to acquire that data, each has its strengths, and each has its limitations. As a friend taught me several years ago, the most accurate perspective you

Calcium chloride (CaCl) test

in-situ relative humidity (RH) test

Electrical moisture meter test

PHOTOS COURTESY OF NWFA

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