A.Tandy Reeves, a certified flooring inspector and CEO of Flooring Inspection Training Services in Tulsa, Okla., responds: While there are several possible causes for the cupped flooring, condensation due to a lack of insulation probably isn’t one of them. Cupping is always caused by a moisture imbalance from the bottom up, either at the time of installation or over the life of the flooring. Because the cupping seems to be evenly distributed over the entire house, the most likely cause is that the moisture content in the subfloor was elevated before installation and the flooring wasn’t properly acclimated. To prevent such problems, the moisture content of the subfloor and the new wood flooring must be within 2 percent to 4 percent of each other prior to installation.

Another possible cause is that the plastic covering the dirt in the crawlspace isn’t sealed to the walls or doesn’t cover the ground completely, elevating the relative humidity underneath the floor. Inadequate cross-ventilation in the crawlspace would compound the problem; typically the area of the vents should equal 1.5 percent of the total...

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