GALVALUME or ZINCALUME ROOFING: Aluminum-Zinc - Combine the chemical action of zinc and the barrier protection of aluminum. Galvalume was developed by the Bethlehem Steel Corp. and is described in ASTM A-792. This make-up is 55 percent aluminum and 43.5 percent zinc and 1.5 percent silicone. This product was a great improvement over galvanized material.  Zincalume is a registered trademark of BPI Steel.