Cupping

Over time, your hardwood flooring can develop a variety of issues, including cupping. Cupping occurs when moisture seeps into your hardwood flooring and the edges become higher while the middle section stays lower or sinks. Hardwood cupping could lead to other problems and even point you to a bigger issue that's creating this one.

cupping

Cause

Cure

Do not try to repair a cupped floor until all of the sources of excess moisture have been found and eliminated. This can only be proven with a moisture meter which takes readings of the subfloor underneath. As long as the wood is not permanently misshapen or damaged, the flooring should return to its initial shape and size once the excess moisture is eliminated. This may take weeks, months, or even an entire heating season.

Trying to sand a cupped floor while it is still moist may create additional cupping once the floor dries. Flooring which does not go back to its previous shape, even after an entire heating season, is likely permanently misshapen.

For flooring that has cupped from drying, relative humidity should be increased. Relative humidity below 20 percent is considered extremely dry for wood flooring; the best solution is adding humidification.