DuPont™ Styrofoam™ Brand Plazamate™ Extruded Polystyrene (XPS) Foam Insulation is designed for installation above waterproofing membranes in commercial plaza deck applications. Styrofoam™ Brand Plazamate™ Insulation helps the roof membrane maintain a steady temperature, minimizing the harmful effects of freeze-thaw cycles, weathering and physical damage both during and after construction.