Standing Seam: Steel, Aluminum, Zinc, and Copper.
Steel: Steel is the most common and least expensive metal. It can be an excellent choice for roofing, because it is very strong and durable.
Galvanized steel has a fair level of protection against the natural elements so that it will not rust under normal environmental conditions. Two methods are used to galvanize steel. G-90 steel has been hot dip galvanized with a coating of zinc.
Galvalume is an alternative coating that offers a higher level of protection, which is composed of a blend of aluminum and zinc. Both coatings can prevent corrosion and rust very effectively, and can usually enable properly-installed steel roofs to last for upwards of 50 years.
G-90 steel is created by dipping sheets or coils of steel in liquid zinc, so that a protective layer of 0.9 ounces or more of zinc is formed. This layer can prevent the steel from becoming corroded or oxidized, which creates what is generally known as rust. G-90 steel is very well protected, even when it is cut or scratched.
Galvalume steel is a better option for roofs that are exposed to a somewhat salty area such as the marine environment. Although G-90 steel provides excellent protection against the elements, which is also enhanced by a cool Kynar coat paint finish, it is not as effectively protected against the corroding properties of salty air as galvalume steel.
Aluminum: Aluminum is another common material used in metal roofing, although it is not used as often as steel, largely due to its higher cost. Many contractors prefer to use steel roofing because it is cheaper, so it can be more difficult to find someone who will install aluminum roofing. Aluminum is naturally resistant to corrosion and rusting. It can therefore be a good choice for roofing in areas that are exposed to salty air. Aluminum is also much lighter than steel, so it can be much easier to handle and install.
Aluminum may not be suitable for panels measuring 35 feet or longer.
Aluminum is generally not as structurally strong as steel. While this is usually not a problem, it can become an issue if you need panels of 35 feet or longer, when it may be necessary to use a stronger metal, or higher gauge material such as steel.
In terms of longevity, aluminum roofs will generally last longer than steel ones, and they will not corrode, even when install in close proximity to the coastal area. Another argument in favor of using aluminum is that the difference in the cost of the materials is almost negligible between the two.
Zinc: As regards the material zinc, the double standing seam is seen as a further development of the original hollow seam or the simple standing seam. First mentioned in the relevant literature in 1899, it is the preferred choice over other systems for roof pitches under 25°. The minimum pitch here is 3° (approx 5.2%). The term “double lock standing seam” characterises one of the classic longitudinal joint types used for panels installed next to each other forming a rainproof layer. On international markets it is the 25mm high double standing seam manufactured with pre-profiled panels that has established itself as the market leader.
The Zinc profile is folded and closed manually or mechanically using hand formers or seam closing machines. Special shapes such as convex and concave curves or tapered panels can be produced without any problem. Traditional architecture or modern design will be enhanced by the elegant lines of the double standing seam thanks to its wide range of details.
Copper: Copper is a roofing alternative that can be attractive to many homeowners, because copper can be such a beautiful material. However, it usually tends to be used more for decorative details rather than for the whole roof, mainly because it is very expensive. Copper can also be used to roof a small section, such as a roof of a bay window to provide an attractive trim, or for flashing on an asphalt shingle, or slate roof. A copper roof can last for hundreds of years, although there is a very minor concern that they may be subject to some damage from acid rains, which could reduce their lifetime.