Residential metal roofing is generally made of copper, aluminum, or steel. Aluminum sheets do not require a metallic coating but actually do get painted. Request a FREE Roofing Estimate Copper, often thought of as a natural metal product, isn’t painted or coated, being that it weathers without any corrosion. Energy Efficient, Wind Resistance, Low Maintenance. Copper is at times used for special features, such as the roof of a special bay window. Steel roofing products are coated with either galvanized zinc or a mixture of aluminum and zinc called galvalume or zincalume. Out of the two, galvalume offers a longer service. The coatings are typically offered in several thicknesses the thicker the coating means the longer the service.