We poured a concrete floor for our structure. After leveling the space by digging down a bit, we put up 8" forms. For the next step we put down recycled 3" closed-cell foam and covered it with poly. We left the center open for drainage and brick so we could access the power and water if repairs are needed. The pipe next to the shovel is the hydrant.The floor tilts to center 1"/3' to keep water from freezing the walls loose from the base.