Installing Plywood Flooring Over Concrete- any homes today are built over a concrete slab, rather than a full basement. While a basement is nice to have, it’s an added expense that many first-time homeowners just can’t afford. But when they want to upgrade their home later on, that concrete slab can be a problem. One way it is a problem is for installing hardwood flooring. Before hardwood flooring is installed over concrete, a plywood subfloor must be installed.