STYROFOAM™ Brand Ribbed ROOFMATE™ Extruded Polystyrene Foam Insulation is designed for use above waterproofing membrane in protected membrane systems (PMR) that include pavers or patio stones as primary ballast. STYROFOAM™ Brand Ribbed ROOFMATE™ Insulation incorporates ribs on the upper surface that extend the length of the panels. Drainage channels are also incorporated into the lower side edges of the panels. In paver/patio stone applications, it is recommended that a drainage layer, which normally takes the form of a paver/ pedestal arrangement, be incorporated between the insulation and ballast to facilitate moisture dissipation. The ribbed configuration eliminates the need for expensive pedestals. STYROFOAM Brand ROOFMATE Extruded Polystyrene Foam Insulation is a type VI extruded polystyrene foam insulation designed for use above waterproofing or roofing membranes in protected membrane roofing (PMR) applications. It helps the roof membrane maintain a steady temperature, minimizing the harmful effects of freeze-thaw cycles, weathering and physical damage during and after construction.