Things You'll Need
Plastic vapor barrier
Powder actuated nailer
The subfloor separates a home's concrete slab from the finished flooring material: hardwood, laminate, carpet or tile. Because it is relatively inexpensive, durable and easy to cut, plywood is commonly used for subfloors. A plastic vapor barrier prevents moisture from seeping from the concrete and into the wood, while the plywood provides a smooth, flat surface on which to lay flooring material. Plywood can be attached to concrete using concrete nails and a hammer, but a powder actuated nailer is exponentially more efficient.
Cover the entire concrete area with the plastic vapor barrier. Cut the plastic with the utility knife so that it is flush with the walls, columns and corners.
Lay the first plywood sheet on the floor in a corner. Lay a second sheet at the end of the first and nail it to the floor with the powder actuated nailer, driving in a nail every 6 inches. Continue laying and nailing plywood, end to end, until you reach the opposite wall.
Cut a sheet of plywood in half. Lay it at the beginning of the next row, adjacent to the first row, and nail it to the concrete. Set the other half aside to use at the end of the row. Nail and lay plywood until you reach the opposite wall.
Begin the next row with a full sheet and continue alternating full and half sheets to begin rows until you have covered the entire floor.