SchluterÂ®-KERDI-BOARD is a multifunctional tile substrate and building panel, which can also be used for creating bonded waterproofing assemblies with tile coverings. It consists of an extruded polystyrene foam panel, with a special reinforcement material on both sides and fleece webbing for effective anchoring in thin-set mortar.KERDI-BOARD allows the installer to prepare and create a broad range of substrates and building elements for the installation of ceramic and natural stone tile that are flat, level, plumb, square, and dimensionally stable. With suitable preparation of the abutting seams and joint areas, the panel may be used for bonded waterproofing assemblies.The boards are simply cut to size with a utility knife. The gridlines, which are printed on the surface, are helpful for neat and quick cuts and installation. Tiles can be installed directly over KERDI-BOARD using the thin-set method.