There are two generic types of metal roofing systems for residential use: concealed fastener systems and exposed fastener systems. Generally, exposed fastener systems cost less than concealed fastener systems. Depending on the aesthetic look you are tying to achieve, your trained professional contractor, or Lyon Roofing & Supply can help you choose the system right for you and your roof design.
Galvanized steel is coated with zinc for corrosion resistance. Galvalume steel is coated with a predominantly aluminum alloy, also to achieve corrosion resistance. Both galvanized and Galvalume are available in various grades. The grade is determined by the thickness of the zinc or aluminum coating applied to both sides of the steel. G-60 is the recommended minimum grade of galvanized steel and AZ50 is the recommended minimum grade of Galvalume if it is to be painted. AZ55 is recommended for Galvalume if it is to be mill-finished or have a clear coat.
Other metals being used include aluminum, copper, zinc, stainless steel and terne. Aluminum is used for its corrosion resistance and malleability -- such as its ability to be formed into detailed wood shake profiles. Aluminum roofing always has a paint finish or anodization applied to it for color and extra durability. Copper, zinc and stainless steel more commonly are used without additional coatings.
Copper is used for its durability and characteristic patina. Zinc also is used for its corrosion resistance, malleability and low-gloss gray look. Stainless steel is used to achieve a lasting, bright, silver metallic look or to meet the demands of an exceptionally corrosive environment.