Cupped floors is an indication of extreme moisture on bottom of the cupped wood. If the floor is over a crawlspace check the humidity level below the floor. If the cupping is a seasonal thing like it would be over a summer damp crawlspace. The cupping goes away during the winter months. Sanding the floor when cupped reverses the problem during the dry time of the year. Cupped wood floors may also have mold growth on the bottom.