Johns Manville’s XSPECT® ISOfoam APF board consists of a uniform closed-cell polyisocyanurate foam core bonded on each side with a foil facer. Polyiso provides one of the highest R-values per inch of any rigid insulation (R-6.0 at 1 inch). R means resistant to heat flow. JM XSPECT ISOfoam APF is produced with an EPA-compliant hydrocarbon-based blowing agent that has zero Ozone Depletion Potential (ODP) and virtually no Global Warming Potential (GWP); it also meets both CFC- and HCFC-free specification requirements. Polyiso is one of North America’s most widely used insulation products and has been cited by the EPA for its responsible impact on the environment.