Hardwood floor installers often use the term “level” when referring to subfloors. While it’s desirable to have a level floor, most homes have a variance of a room. Hardwood floors do need a flat subfloor surface in order to prevent them from buckling after installation. Creating a flat subfloor involves lowering the high spots and raising the low ones. Each requires different processes to accomplish.
Check for levelness
- Remove any obstacles from the floor. Clean it well with a wet-dry vacuum. Pound nails into the subfloor with a hammer and set screws slightly below the surface of the subfloor with a screwdriver.
- Pass a long carpenter’s level or straight board across the floor in all directions. Get down on your knees and look for daylight under the level or board.
- Mark the high and low spots on the subfloor.
Remove High Spots
- Cover the openings to the other rooms of the house with plastic sheeting held in place with painter’s tape to prevent dust from going everywhere. Cover heating vents as well.
- Open windows to allow adequate ventilation. Put on a dust mask.
- Place medium grit sandpaper on a hand sander. For large areas, you can use hardwood flooring edger to make the job go faster. Models with dust catchers help minimize dust in the house. Sand off the high spots on the subfloor. Remove any rough edges between plywood subfloor joints with the sander as well.
- Vacuum the dust away.
Raise Low Spots
- Stir pre-mixed cementations leveling compound with a trowel. Spread the leveling compound over the low spots with a trowel. Feather the edges to blend with the surrounding subfloor.
- Sand any rough edges of the leveling compound after it dries overnight, using medium grit sandpaper.
- Vacuum away any dust.