Manufactured with an extruded polystyrene foam core and a special coating on both sides, JACKOBOARD® construction boards form an ideal base for tiling. The surfaces of the JACKOBOARD® system provide an extremely strong bond and can be used on virtually any substrate. The boards are waterproof, thermally insulating, lightweight and very strong. Jackoboard Plano Insulated Tile Backer Boards - 1200x600x4mm X10 boards