... ,sun-resistant,anti-aging, tear proof.3.antifreeze, corrosion-resistant, 4.Waterproof, mildrewproof, tear Resistant, acid Resistant , UV Resistant, shrinkproof ... Roof Insulation Foil is made of five layers of materials.The surface is metalized pet film,middle layer is polymer ... StrengthN/25mmInterior layer3.3Exterior layer3.7Permeability2000mm water column,2hImpermeable aluminium foil roof insulation