Home Depot has subfloor system

which is a 2 feet by 2 feet wood and 1/4 feet think with plastic underneath . Put the subfloor system underneath the hardwood. It works beautifuly. We finsished our basement with subfloor systems over the concret without a single nail, and then stabble the hard wood on the top of the subfloor system. The subfloor system keeps out the moinsture so that hardwood does not get wet. Good luck.