Galvanized steel has long been considered the standard for corrugated metal roofing. This is because this particular material is relatively inexpensive and has excellent physical properties. Galvanizing the steel takes care of the one thing that untreated metals tend to lack – corrosion (rust) resistance. The zinc coating provides many advantages when it comes to keeping the roof rust free, but it also has its drawbacks. In order to keep the metal safe, the zinc preferentially reacts with oxygen in the environment to form a barrier against this nasty gas getting to the steel. This causes the exterior appearance of galvanized corrugated metal roofing to change over time, and not always in a way considered to be attractive. While it may not be the prettiest choice, galvanized steel’s excellent physical properties make it suitable for most jobs.
Stainless steel, while a little weaker than galvanized steel, provides far better natural corrosion resistance. This means that it doesn’t require any coatings which may change in appearance over time. Because of this, stainless steel corrugated roofs tend to retain their initial appearance for many years or decades. Stainless steel may not be suited for environments where harsh conditions are seen regularly, but it’s definitely an ideal choice if the look of the roof’s exterior is as important as its physical prowess.
Modern Engineered Materials
Modern engineered materials make use of advances in materials science to take advantage of specific alloys for the metal roofing and coating. While steel is still most often chosen as a base material, bonding it to planned coatings can provide additional corrosion resistance without detracting from the exterior look of the roofing. This effectively means that you can have your cake and eat it too. Engineered coatings and materials tend to be more expensive than traditional ones, and should be reserved for cases when they are truly required.