How to Construct Concrete Floors Using Concrete Panels

Excavate the ground to a depth of 6 inches plus the thickness of the concrete slabs, adding or removing soil as necessary to create a level surface. If patching a section of the basement floor, excavation may be unnecessary, but you'll need to use a concrete saw to cut the area to 1/4-inch larger than the concrete panel.

Spread 4 inches of crushed rock or gravel over the soil and pack it down with a plate compactor or hand tamper until level. For basement patches, a base layer of gravel probably is already present, but you might need to pack it back down with a hand tamper.

Spread a 2-inch layer of masonry sand over the gravel layer and use a 2-by-4-inch board to level it. For basement patches, add sand up to the bottom of the existing concrete floor. Pack the sand down with a plate compactor or hand tamper.

Cover the sand with a vapor retarder material, such as polyethylene film, overlapping the seams 6 inches. This prevents water from seeping into the concrete, which could weaken the concrete and increase the risk of cracks.

Set the concrete panels in place in the desired pattern, starting from the inside corner of the patio floor and working your way out. Leave a 1/4-inch gap between each panel to allow room for expansion and contraction so the panels do not crack. When you get to the outer edge of the floor, you might need to cut the panels to fit with a concrete saw.

Push polymeric sand into the crevices between slabs in a patio floor; a push broom makes it easy to pack all the crevices. Moisten the sand with a gentle mist from a garden hose to pack it down slightly, add more sand to fill the crevices to the top, then spray the patio again. Polymeric sand is a mixture of masonry sand and cement mix that hardens as it dries to bond the panels together, but is not so rigid that it prevents expansion and contraction as a result of temperature fluctuation.

Insert an expansion joint between basement panels or between a patch and the existing concrete floor, and then fill with wet concrete mix or pure silicone sealant. Use a masonry trowel to apply the concrete and smooth with a hand float. Expansion joints allow the concrete to expand and contract without cracking.