AlinO-Backer Board is ideal to use over any substrate or construction. It is your all-in-one solution to create partition walls, insulate floor for electrical underfloor heating, or make panels in shower room, steam room or in any wet area. It's strong, light and waterproof. High density extruded polystyrene (XPS) is used as the core material which is reinforced on both sides with fiberglass mesh and special mortar