The Problem
I was called to inspect an engineered floor because there were individual cupped boards randomly located throughout the floor.
What Happened
The 1⁄4-by-5-inch engineered planks were stapled to OSB over a crawl space with foundation vents in a new home in South Carolina. The owners noticed the cupped planks immediately after installation.
After communication problems, the retailer replaced some but not all of the cupped planks, and the homeowners decided to live with the floor. After a few years, they asked the retailer: If they replaced the flooring, would the same problem happen again? The retailer contacted the manufacturer, and instead of answering the question, a claim against the flooring and installation began. An inspector determined the problem was moisture from the crawl space due to two closed vents, although moisture measurements were within industry tolerances. After the inspection, the homeowners again asked if the problem would reoccur with new flooring, but got no response.
The Inspection
I was hired by the homeowners. By then, they had gone from wanting an answer to a simple question to assigning blame and requesting full replacement. I found, out of hundreds of planks, approximately 35 (randomly located) that were cupping. No high levels of moisture were measured in the wood, subfloor or crawl space joists. There was no end-joint checking from wet mopping, no end-joint peaking, no gaps at the end joints and no checks. The flooring, except for the cupped planks, looked good.
RELATED: How to Prevent Cupping and Worse in Summer Months
Moisture will not affect one plank but not the plank next to it, and in this house, moisture did not cause the planks to cup—at least, not site moisture in the home or crawl space. Engineered wood flooring is, simplistically, plywood. If the construction of the engineered flooring is unbalanced, it can warp, or cup, as some of the boards did in this case. Cupping from unbalanced construction can be caused by moisture differentials in the plies during pressing, species used as veneers with significantly different shrink/swell characteristics than other layers, veneers not turned correctly and/or juvenile wood.
How to Fix the Floor
The cupped planks should be replaced.
In the Future
It's difficult for most people to know ahead of time if the flooring is unbalanced. What's interesting in this case is that, if anyone had simply answered the initial question from the homeowners, this situation would have been avoided. Remember Cool Hand Luke? "What we got here is failure to communicate."
To read the publication "Some Causes of Warping in Plywood and Veneered Products" from the U.S. Forest Products Laboratory, click here.
