Q: My hardwood is in a convex shape; meaning, the two sides of the wood are up, but the middle part is down. A “C” shape. What is going on and how can I fix it?
A: This is called “cupping”. When the centre is raised it is called “crowning”.
Both are caused by excess moisture in the wood. It can be caused by extremely high humidity, dampness under the floor in a crawl space or a water leak from somewhere in or about the house. It could be from the roof or a window with large amounts of water seeping inside the wall and under the floor. Or could be from a leaking dishwasher, bathtub etc.
Find the source of moisture and eliminate it. A dehumidifier may help. When the moisture in the flooring is within normal range (you need a moisture meter) and it hasn’t flattened out on it’s own, it would have to be sanded flat.
Related Q: Our sink clogged and our dishwasher had leakage in the kitchen, which has tile flooring. On the other side, in the living room, our hardwood floor started cupping – the next day. Even though we had cleaned up all the water. Does cupping happen this soon after water leakage or could it be from previous flooding?
A: Water has likely gotten under the floor. Cupping occurs when the bottom side of the wood is wet and the edges curl upward. Crowning, when the center of the board raises is from excess water on the surface. This seems clear. The dishwasher leaked and the water ran onto and under your wood floor. Unless it actually heaves I would let it fully dry out and see what it does. You can’t do a thing with it until then unless you intend to replace the floor, in which case removing it as soon as possible will help the drying of the sub floor along.