Crowning

The opposite of cupping, crowning occurs when a board’s center is higher than its edges. A common cause is moisture exposure or imbalance. If the surface of the floor is left exposed to water or left in humid conditions for an extended period of time, the moisture can saturate the wood flooring and cause crowning. Another cause is that the floor was previously cupped, but was sanded before the moisture content returned back to its normal state. In this case the floor should be given time to dry before sanding. The sanding process can cause the raised edges of the board to flatten while lifting up the middle of the board if the floor is sanded while the boards remain cupped and moisture is still present.