Vapour-barrier insulation. 8 ft. x 4 ft. x 2 in. Provides maximum insulation, eliminating heat loss. Retains insulating properties over the long term. Reduces the risk of mold. Maximizes the results of generated heat. Does not attract insects or small animals that can destroy insulation. Contains no HCFCs. Can also be used to insulate interior walls. Expanded cellular polystyrene insulation with built-in reflective vapour-barrier membrane. Combines all the advantages of rigid insulation with those of reflective vapour-barriers. Thermal resistance value: R-11. Installs quickly with 3-in. x 1-in. nailing strips.