DuPont™ Styrofoam™ Brand Roofmate™ Extruded Polystyrene (XPS) Foam Insulation is designed for installation above waterproofing or roofing membranes in protected membrane roof (PMR) or green roof applications. Engineered for use on heavyweight decks (e.g. reinforced concrete) with a ballast layer of gravel or concrete slabs, Styrofoam™ Brand Roofmate™ helps the roof membrane maintain a steady temperature, minimizing the harmful effects of freezethaw cycles, weathering and physical damage during and after construction.