With infrastructure demands rising across Africa and the critical need for more sustainable manufacturing, selecting the right materials for structural and roofing applications has become a key decision for engineers, architects and developers. The International Zinc Association’s (IZA) Africa desk highlights the enduring performance and versatility of hot dip galvanised structural steel and continuously galvanised roof sheeting, particularly in the face of tough environmental conditions.
“Whether you are designing for deep South African underground mines or the corrosive local coastline, galvanising provides a proven and cost-effective corrosion protection system that extends the life of steel by decades,” says Simon Norton, director of IZA Africa.
Hot dip galvanised steel, coated with a layer of zinc plus an organic coating, is especially valued in structural and roofing applications for its durability, low maintenance requirements and lifecycle cost benefits. When exposed to the atmosphere, zinc forms a protective patina of complex zinc carbonate that shields steel from corrosion, even in aggressive environments. Zinc offers cathodic protection to the underlying steel as well. “It is a double whammy of benefits,” says Norton.
Inland vs coastal applications
Norton advises that while standard hot dip galvanised steel performs well in inland areas with low to moderate corrosion exposure, additional considerations are necessary for coastal or industrial zones. Inland in South Africa, the extensive deep underground mining industry will benefit substantially from the use of galvanised steel for mine shaft steel and buntons, as these are exposed to very corrosive mine waters and conditions underground.
“In sea salt sprayed coastal areas, it is essential to use thicker zinc coatings on steel sheet or duplex systems, namely galvanising followed by paint, to withstand the increased corrosive impact,” explains Norton. A site-specific corrosion risk assessment using ISO 9223 should guide the choice of coating type and thickness for continuous galvanised roof sheeting, with SANS 121 (ISO 1461) as a benchmark for hot dip galvanising standards in South Africa.
Sustainability and the circular economy
Galvanised steel contributes to sustainability goals, aligning with global green building practices. Zinc is a natural, recyclable metal and galvanised steel can be reused or recycled without loss of the physical properties of the basic contents, namely steel and zinc.
“Galvanising supports Africa’s infrastructure development by increasing material lifespan and by lowering total environmental impact,” says Norton. “IZA Africa is committed to providing expert knowledge about appropriate zinc applications to ensure safe, economical and long-lasting infrastructure across the continent.”
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