In solid hardwood flooring applications, cupping – when the sides of the floor boards are raised from the center – often occurs as a result of:
- Increased moisture in the bottom of the flooring
- Increased water vapor and relative humidity of the air
Eliminating the moisture source will typically resolve instances of slight to moderate cupping. The most effective way to dry wood involves the combination of heat, moving air and low humidity. For the best results, consider the assistance of a commercial drying service.
Engineered flooring – three to five layers of hardwood applied to a plywood backer - can cup if the moisture content is lowered. (The face layer pulls against the plywood base, curls upward causing the cup.) In cold regions of the country that are prone to long heating seasons, the condition can occur each year. And unfortunately, longer acclimation times usually do not lower the possibility that cupping will occur.
“It is so important that hardwood be installed under the proper moisture conditions and moisture content.”
- Ensure that the supplier/vendor is knowledgeable about the specific product, and how and where it will be used.
- Employ the services of professional, certified installers.
Information Source: National Wood Flooring Association and Andrew St. James, Ph.D.
“Technical Manual C200: Problems, Causes and Cures”