How to Replace Plywood Subflooring

Putting in a new plywood subfloor is a good way to start off a new flooring project.

Over the years, a plywood subfloor can incur damage and warp, requiring replacement. Once you have removed the flooring in a room, you can evaluate the state of the subfloor and take steps to remove and replace it. The largest benefit of replacing a subfloor is that is creates a clean canvas from which you can redecorate a room with new flooring, breathing life into a tired-out space. With a few simple tools and a little time, removing the old one and installing a new plywood subfloor is remarkably easy.

Things You'll Need

• Pry bar
• Chalk line
• Utility knife
• Chisel
• Plywood as needed
• Wood putty
• Construction adhesive
• 20-ounce straight claw framing hammer
• Circular saw
• Tape measure
• Galvanized flooring nails (#6 or #8) or drywall screws

Instructions

1. Remove the existing flooring. Use a pry bar to loosen trim from walls and detach tack strips if the old floor was carpeted. Place a piece of plywood behind the pry bar to protect the wall for the trim, and do the same for the flooring when removing tack strips. Wedge the pry bar underneath trim and tack strips and use the leverage it creates to detach it from the wall or floor.

2. Measure the area with a tape measure. Measure the width and the length of the room to obtain a square footage for the area. Obtain enough plywood to facilitate the installation of a new floor based on these measurements. You can purchase plywood from local home improvement stores or lumberyards; it most often comes in sheets. Cut the plywood to account for any doorways and closets in the room before installation using a circular saw and the measurements from the room.

3. Cut out the old subfloor using a circular saw. You can rent a circular saw from a home improvement store if you do not already own one. Be sure to cut only 1/8-inch deeper than the subfloor to avoid hitting plumbing or electrical wiring and to avoid damaging floor joists. Once the bulk of the floor has been cut out, knock the remaining subfloor out of place using a hammer and chisel, being careful to not hit floor joists or walls.

4. Lay a bead of construction adhesive on the floor joists before laying the new plywood. The floor joists are wooden 2-by-4s that are exposed when the subfloor is removed. Lay each sheet of plywood on the floor joists and nail them in place using galvanized flooring nails or drywall screws. Nails can pop loose over time, causing floor squeaks, thus the benefit to using drywall screws is the smaller chance for floors to move and squeak over time. Repeat this installation process for the entire subfloor. Once all of the plywood is put in place, the floor is ready to be prepped for the installation of the selected new floor covering.

References

• Online Tips: Replacing Plywood Subfloor
• I Can Fix Up My Home: Plywood Subfloor