FOAMULAR® 604 & 604 RB extruded polystyrene insulations are specially designed for use in Protected Roof Membrane Assemblies (PRMA), where the insulation is placed directly over the membrane. The compressive strength of FOAMULAR® extruded polystyrene insulation provides the integrity needed for long-term roof performance. Extruded polystyrene is the type of insulation recommended for PRMA applications. Owens Corning offers four specific types of FOAMULAR® extruded polystyrene insulation for this use: FOAMULAR® 404 and 604; and FOAMULAR® 404 RB and 604 RB. Both the 404 RB and 604 RB extruded polystyrene insulations feature drainage channels running the length of the panel. These are excellent extruded polystyrene products.
