Download PDF version (192.8k) Log In or Register to view the full article as a PDF document.
Q.Last spring, I installed floating engineered flooring over the original vinyl-covered concrete-slab floor of an old New York City apartment. Even though I followed the manufacturer's installation guidelines, the 8-inch-wide planks began to cup, and cracks measuring 1/32 to 1/16 inch opened up between some of them during the following winter heating season. I assume that the cracks and cupping were caused by this building's wide swings in relative humidity, and that the flooring will return to normal this summer. But my client is unhappy and claims that either the flooring or the installation is defective. Is there a way to remedy this situation, short of removing the flooring and starting over?

A.Tandy Reeves, a certified flooring inspector and CEO of Flooring Inspection Training Services in Tulsa, Okla., responds: Even though engineered hardwood flooring is more dimensionally stable than solid wood flooring, the wood-veneer layers that make up the face are susceptible to shrinking and swelling with changes in temperature and humidity. It's common for the top layer to face-check when the humidity varies as much as you describe, but most of that may disappear as the relative humidity elevates again over the summer.

As with all wood floors, one key to a successful installation — and to the long-term life of the wood floor — is to install and maintain the floor at a temperature between 60°F and 80°F, with the relative humidity measuring from 30 percent to 50 percent.

Another is to install the flooring when it has reached equilibrium with the room environment, which is when the moisture content of the subfloor and that of the new flooring are within 2 percent to 4 percent of each other. This should be checked using a good pin-type moisture meter, and the readings documented in case there are issues with the installation later on.

If the flooring doesn't return to its originally installed condition after seasonal humidity levels return to normal, you can replace the worst planks (rather than the entire floor). After cutting out and removing a plank, you may need to use a router and rasp to clean dried glue off the tongue-and-groove profile of the remaining sections of flooring. Then trim off the underside edge profiles on the ends and one side of the new plank so it can be slipped into position; apply yellow carpenter's glue to all of the edges; install the new plank; and weight the installation for at least three hours, or until the glue has cured.

Check with your flooring manufacturer for its step-by-step instructions for plank replacement.