However, before any of these items are selected and installed, we take the extra and necessary step to inspect and properly prepare your floors – the floor you see and the one beneath it you can’t see. Substrate floors are the foundational layer below your visible flooring that essentially hold your room in place. Substrate flooring must be stiff and strong enough to carry the room’s load – including heavy tubs, vanities, cabinetry, appliances, tiles, etc.