All-purpose foam panel insulation for masonry and other applications. Owens Corning FOAMULAR extruded polystyrene insulation is ideal for wall furring, perimeter/foundation, cavity wall, crawlspace, pre-cast concrete, under slab, sheathing and other applications (Not approved for roofing). Owens Corning's patented Hydrovac process technology makes the unique closed-cell structure of FOAMULAR extruded polystyrene insulation highly resistant to moisture, retaining its long term R-value year after year even following prolonged exposure to water leakage, humidity, condensation, groundwater and freeze/thaw cycling.