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Using continuously galvanized steel for light steel frame building

Light steel frame building (LSFB) is not the same as prefabricated or ‘kit’ buildings, as it is rather a building method. Another term is ‘off-site’ construction, due to the fact that a lot of the manufacturing takes place in factories, whereafter the components are transported and assembled on-site. LSFB consists of structured wall panels, trusses and floor joists that are assembled using cold-formed steel sections, which in turn are made from thin-gauge high-strength continuously galvanized steel sheet.

Hot-dip galvanized substrate is produced on continuous zinc coating lines from either cold-rolled (thickness range 0.27 mm to < 2.0 mm) or hot-rolled (thickness 2.01 mm to 3.0 mm) steel substrate in coil form. It is produced to the requirements of EN 10142, EN 10147, EN 10143, ASTM A924, SANS 4998 or SANS 3575. On the other hand, rolled zinc products such as Rheinzink and Verozinc, which include the alloying elements copper, aluminium and titanium, and conform to standard EN 988, are only suited to roofing and cladding of buildings. These products are made from near pure zinc sheet, as opposed to continuously galvanized sheet, where the molten zinc is coated onto thin steel sheeting. Rolled zinc can be used in façades, cladding, roofing, gutters and drain pipes, as well as for ornamental applications, and even as flashing. Rolled zinc products have a long service life and can be recycled and reused. However, with LSFB structures, the material of choice is continuously galvanized steel sheet that subsequently gets shaped and formed into the elements that make up the building skeleton. Zinc generally corrodes at a low rate due to the protection offered by the resilient zinc patina formed by the reaction between the metallic zinc surface, the oxygen in the air and carbon dioxide. This compact, bonded and insoluble patina layer blocks exchange between the atmosphere and the zinc. Zinc is used extensively to galvanize steel to prevent corrosion. Speak to an expert if you want to apply galvanized steel or roofing close to the sea, within 1 km to 2 km of the high-water mark, as care must be taken when used at the coast under very corrosive conditions. Read more: Using continuously galvanized steel for light steel frame building