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. The boards are simply cut with a utility knife. The gridlines, which are printed on the surface, are helpful for neat and quick cuts and installation.