DIY Laying a Plywood Subfloor

Nail the plywood directly to the floor joists.

Plywood subflooring is the foundation that is nailed directly to the floor joists. After the subfloor is in place, a layer of particleboard is nailed to the plywood, and the final tile, carpet or other flooring is placed on top of that. The subfloor must be installed flat, with no inconsistencies, or problems will occur when the particleboard and tile are installed later. You can install your own subfloor with a hammer, nails and a circular saw.

Things You'll Need

• Plywood
• Hammer
• Nails
• Circular saw

Instructions

1. Lay one full sheet of plywood across the joists parallel to the floor. Push the corner of the plywood hard into the corner -- kick it with your foot or use a hammer to get it into the corner and flush against the wall. The side of the plywood opposite the wall should be parallel with the edge of another floor joist, with half of the floor joist showing. The other half of the joist will be where the next piece of plywood will butt against the first one. The edges of the plywood should always be supported by joists.

2. Check the alignment. If the plywood hangs over the side of the joist, you will need to trim it back with the circular saw so that it shares half of the joist with the next piece of plywood.

3. Nail the plywood to the floor joists around the perimeter of the plywood. Space your nails at 8-inch intervals. Hit the nails just hard enough to bury the head just below the surface of the plywood, creating a small divot where the nail head is.

4. Lay the next piece of plywood beside the first piece. The edge of the plywood should butt up against the first piece, sharing the floor joist together, the single joist supporting both pieces. Nail it down around the perimeter the same way you did the first piece.

5. Lay down all the consecutive pieces of plywood. Trim the edges so that all of the plywood edges are supported by a floor joist. Cut pieces to fit around walls if necessary with the saw. Make sure that all pieces are supported on the edges.

Tips & Warnings

• You can use construction adhesive on the plywood if you like, but it's not necessary.

• Always wear safety glasses when working with plywood.