RoofRunner® AIR is a breathable synthetic roof underlayment with a multilayer coated structure that promotes rapid roof deck drying. Unique permeable layers allow moisture to escape and help to prevent mold, rot, and structural damage. Use as a water-resistant layer beneath asphalt, slate, wood, metal, or tile to help defend against wind driven rain and trapped moisture. This lightweight underlayment is designed for easy installation and walkability in any weather. It remains flexible at all temperatures and lays flat with strong adhesion to prevent wrinkles and buckling. The RoofRunner AIR Advantage With innovative technology woven into each layer, RoofRunner AIR is an important component of a properly ventilated, dry, and healthy roof. Optimal permeability of 15 perms High Strength to Weight Ratio: Light weight with high durability. Remains Flexible: Easy to install in freezing or extremely hot conditions. Excellent grip to roof deck: Helps walkability on the roof deck. Reduced Replacement: Minimize stretching around fasteners with no blow-offs. UV Stabilized: 180 Days UV Exposure. Peace of Mind: Protected by CertainTeed Lifetime Limited Warranty. Versatile: For use under asphalt, slate, wood, metal, or tile.