For filling and leveling surfaces prior to the installation of carpeting, vinyl floor tile or sheeting as well as ceramic or mosaic floor tile. Use to fill cracks, fasteners or knotholes, and level low areas in plywood subfloors or concrete surfaces. Remains flexible allowing the plywood subfloor to flex without cracking the filled-in areas. For plywood subfloors and concrete. Crack resistant. Can be feather edged. One quart fills 3 to 4 sq. ft. 1/4 in thick.