We purchased 3/8" Brazilian Cherry from Lumber Liquidators in the summer of 2007. We took the old floor up all the way to the 2x8 tongue and groove Doug Fir. 3/4" AC (sanded) plywood was then placed on top of the tongue and groove. Then 15# felt tar paper was then placed on top of the plywood. The hardwood was stapled to that subfloor. We are having slight cupping problems that I had begun to notice about 6 months ago. It has gotten worse over the last months. What is going on? I contacted Lumber Liquidators and they indicated that it was a moisture problem. Where is the moisture coming from? We have black plastic on the floor of our crawl space and insulation in the floor. Could you please advise.

Thank you.

cupping of hardwood floor