Building envelope insulation is designed to reduce energy costs, but rarely is it formulated to contain no ozone-depleting compounds. GAF’s EnergyGuard PolyIso Sheathing is made without CFCs or HCFCs and boasts an R-value of at least 6 per inch, the company says. It is available in 4’ by 8’ boards at ½”, ¾”, 1”, and 2” thicknesses and is suitable for cavity walls, masonry walls, stud walls, exterior stucco, re-siding, and vaulted ceilings in new construction or retrofits.