Bare steel will rust in a couple days when expose to the elements. To prevent this, the surface of bare steel needs to be coated. The majority of steel building manufacturers use red-oxide primer on all structural steel components. There are some that use galvanized light gauge secondary steel as their standard material while leaving the heavy rigid frames with a red-oxide primer. So what is the difference between the two and are there any advantages to galvanized secondary steel?
For most applications red-oxide primer is better suited than a galvanized finish. This is why red-oxide is used in most commercial and agricultural construction from backyard sheds to the tallest skyscrapers. Of course there are some instances where galvanizing is recommended. Galvanizing can be useful in corrosive environments such as chemical plants or coastal roof systems. There are different grades of galvanizing with varying associated costs. Good quality galvanizing is expensive, and it turns a versatile material into a very unforgiving material. Galvanized steel cannot be painted, bent without cracking the finish, or welded without producing toxic fumes. Since a galvanized part can not be painted, any alterations can not be covered up. It is also extremely abrasive and must be handled carefully with gloves at all times. Galvanized steel is not resistant to oxidation when exposed to moisture. Typically galvanized steel will develop white rust which can be unsightly. Red-oxide primed steel can also develop surface rust when exposed to moist environments for extended time periods, but the color of the primer will hide any rust color.
Red-oxide primer is a water based paint and safe for the environment. Once applied to all the structural steel components of a steel building, surface rust is inhibited. The primer is very durable and can withstand the abuse of loading and unloading from a truck as well as all field handling while being erected. Primed steel will also hold up to the weather before the metal building is completed erected. With a primer finish, you have the option to paint the steel any color to match the interior of the building if needed.
Overall, red-oxide primed steel is the way to go for most every steel building application. Greater flexibly, lower cost and esthetically superior to galvanized steel, primed steel is chosen by most builders worldwide.