Abstract: A floor panel having a structural core and a finished surface layer disposed on a top side of the structural core. A substantially water-impervious sheet having a plurality of projections for providing an air gap between the core and a concrete foundation is affixed to a bottom side of the structural core. The finished surface may be carpet, carpet underlayment, or a finished wood or wood-like surface. The floor panel minimizes the effort required to construct a sub-floor whilst dealing with moisture problems typically encountered in installing wooden sub-floors over a concrete foundation.