The structural steel of a pre-engineered steel building is divided into two categories, primary structural steel and secondary structural steel. All secondary steel, roof purlins, walls girts, and all corresponding clips are provided as G-30 galvanized with acrylic coating.
The primary structural steel is the main steel frames of the structure as well as other components depending on the building design. Typically, the primary steel is given one coat of primer paint and that serves as the final finish of the steel. Since all the primary structural steel is within the building and not exposed to any weather, the primer coat is sufficient to keep the steel protected. In specialty application, the primary structure will require additional protection. The available options are as follows:
In addition to the primer coat, the steel is painted with a specialty paint, such as an epoxy, urethane, plural, fire resistant or standard architectural coating. The specialty paint is chosen based on the buildings end use. If there are chemicals being used within the building or if the building is open and near the ocean or if a manufacturing processes within the building make corrosive materials airborne, a specialty paint will provide further protection for the primary structural steel. Structural steel is also painted for architectural reasons allowing the steel to be painted any colour the customer requires.
To galvanize the primary steel of a steel building, the completed components are dipped in a tank of molten zinc providing a protective coating, called hot dip galvanizing. There are many advantages to galvanizing the structural steel of a pre-engineered steel building. The dipping process ensures the entire component is coated, unlike painting where areas can be missed or unevenly applied. The dripping process also results in a thicker coating in corners and alone welds, areas where the greatest protection is desired. Galvanizing can have a higher initial cost than some painting options, though it can be the cheaper option depending on the building, but, as it requires no maintenance, is cheaper over the long term; and generally has a longer life span. Galvanizing also saves time compared to painting. Where an entire building can be galvanized in 1 day, painting it could take a week. Galvanizing also provides LEEDS points due to the higher recycled content of the zinc material used.