19 Construction boards, light weight construction boards, cementitious boards with a foam core, and including all the above for use as backer boards for tile and stone, for bathrooms, showers, and for walls, vanities, shelving, benches, surrounds and floors; Waterproofing membranes for floors and walls; Flooring underlayment for building purposes, namely, uncoupling membranes for use with ceramic, stone and tile floors; Sheathing board