Walk around the subfloor to ensure it is stable. If the subfloor flexes under your foot, fix or replace the subfloor before using Fix-It-All. Fix-It-All will not stabilize the floor, and can create more damage.
Sweep the floor to remove any dust and debris. Mop the subfloor with soap and water to remove any grime and dirt. Allow the floor to dry thoroughly.
Place a level or straight edge over the subfloor to look for uneveness, or valleys.
Mark the low valleys in the subfloor with a pen.
Attach a mixing hook to a cordless drill to mix the Fix-It-All and water together.
Pour the Fix-It-All compound into a clean bucket. Mix 6 1/2 oz. of water with 1 lb. Fix-It-All, or add enough cool water to the desired amount of Fix-It-All to form a heavy, paste consistency.
Pour the Fix-All mixture into the circled, low areas of the subfloor.
Smooth out the mixture into the low areas with a squeegee. Allow the mixture to set for 30 minutes; don't walk over the set mixture for two to four hours and don't replace the flooring for 12 to 24 hours.
Rinse the Fix-All from the drill, bucket and squeegee immediately.