How to Sand a Plywood Subfloor Prior to Hardwood Installation

Remove all loose debris from the subfloor. Use the wet/dry vacuum to vacuum up all the debris. If the floor has carpet glue or carpet padding stuck to the floor, use a razor blade or utility knife to scrape the stuck-on debris off the floor.

Choose the right sander for your job. Drum and floor sanders are larger sanders you can rent. These are good for large projects or multiroom projects. The smaller disk sanders work for small rooms, halls or entranceways.

Plug in the sander and load the sanding disk. The disks need to have a grit of 20 or 36. Large floor and drum sanders may have a vacuum hose port on the sander to attach the hose from the wet/dry vacuum.

Locate the uneven areas in the plywood subfloor. Put on the dust mask and goggles. Turn on the vacuum and the sander.

Go over the uneven areas once or twice with the sander. Pull the sander backward in straight lines across the floor. Check the floor with the level. If the floor is still not level, run the sander over the area once or twice again. Continue until the area is level.

Lean the floor sander on its back wheels and push it to the next location. Continue in the same manner as Step 5 on the rest of the uneven areas. Replace the disk if the sander stops sanding the plywood well.

Sand all corners or tight spots with a small disk sander.

Check the entire floor and make sure it is level. Touch up any uneven spots or bumps in the plywood.

Run the wet/dry vacuum over the floor to pick up any loose debris left from the sander.