Galvalume roofing and siding panels are made of sheet steel coated with a mixture of aluminum and zinc. With its high corrosion resistance and heat reflectivity, it makes an excellent roofing material that lasts much longer than galvanized steel—as evidenced by its 25-year warranty. The matte finish works well with modern, industrial, and even rustic buildings where a more subdued look is preferred over the shiny look of galvanized steel.