Understanding Corrosion Zones in South Africa and Their Impact on Roofing Fasteners

Corrosion is a critical factor when it comes to the durability of buildings, especially in regions like South Africa, where diverse climate conditions can accelerate the deterioration of metal structures. From coastal areas to inland regions, understanding the corrosive potential of the atmosphere is key to selecting the right building materials—especially roofing fasteners. Let’s explore the various corrosion zones in South Africa, how they affect building materials, and what fasteners offer the best solutions for each environment.

Corrosion Zones in South Africa: What Do They Mean?

South Africa’s atmospheric corrosion map divides the country into distinct zones based on environmental factors such as proximity to the ocean, humidity, and pollution levels. These zones offer crucial insights into how fast and aggressively materials like metal roofing and fasteners will corrode over time.

• CX Zone (Extreme Corrosion): Found within 150 meters of the coastline, this zone is characterised by high humidity and exposure to salt spray, making it one of the harshest environments for metal.
• C5 Zone (Very High Corrosion): From 150 meters to 1 km from the coast, this zone sees reduced, but still high, salt exposure. Industrial areas also fall into this category due to the presence of pollutants.
• C4 Zone (High Corrosion): This zone extends from 1 km to 30 km inland and includes regions exposed to moderate atmospheric pollutants and humidity.
• C3 Zone (Moderate Corrosion): Inland areas far from industrial pollution or coastal influences fall into this category, experiencing lower levels of corrosion.
• C2 Zone (Low Corrosion): The least corrosive zone, often found in arid regions like the Karoo and Kalahari, where humidity is minimal and atmospheric conditions are dry.

The Impact of Corrosion on Roofing and Fasteners

Corrosion primarily affects metal roofing materials and the fasteners that hold them in place. Without the right materials, fasteners can weaken over time, leading to structural failures. In extreme cases, they can compromise the entire roofing system, which is why selecting the right fastener for each corrosion zone is essential.

For instance:

• In coastal regions (CX and C5 zones), salt spray accelerates the corrosion of metal fasteners, so materials with high corrosion resistance, such as stainless steel or class 4 coated fasteners, are recommended.
• In industrial regions (C5 zones), pollutants in the atmosphere interact with metal surfaces, making protective coatings vital to prevent degradation.
• In inland areas (C3 and C2 zones), while corrosion is less aggressive, exposure to humidity and occasional pollution still requires durable, coated fasteners to ensure longevity.

Choosing the Right Fastener: Class 3 vs. Class 4

When it comes to roofing fasteners, the classification system provides clear guidance on which fasteners are best suited for different environmental conditions.

• Class 3 Fasteners are typically used in moderate to low-corrosion environments, such as inland regions (C3 and C2 zones). These fasteners have a zinc-aluminium coating that offers a basic level of protection against corrosion, making them a cost-effective option for areas where atmospheric corrosion is less severe.
• Class 4 Fasteners, on the other hand, are designed for high-corrosion zones like coastal areas (CX and C5 zones) or industrial environments. These fasteners come with a superior corrosion-resistant coating, typically made from advanced alloys, which ensures long-lasting performance even in the harshest conditions.

For instance, Corroshield’s range of Class 4 fasteners is specifically designed to withstand high humidity, salt spray, and atmospheric pollutants, making them the top choice for roofing systems in South Africa’s coastal and industrial zones.

Best Fastener Solutions for South Africa’s Corrosive Environments

According to Corroshield’s Everyday Roofing Fasteners, different environments demand different fastener solutions. Here are some top recommendations for fasteners based on the corrosion zones:

• For CX Zones (Extreme Corrosion): Stainless steel fasteners or Class 4 fasteners with advanced corrosion-resistant coatings are critical.
• For C5 Zones (Very High Corrosion): In both coastal and industrial areas, Class 4 fasteners should be the standard. These fasteners provide the necessary resistance against salt spray and pollutants. Additionally, using fasteners with protective coatings that can resist both moisture and industrial chemicals ensures that the roofing system remains secure over time.
• For C3 and C4 Zones (Moderate to High Corrosion): Inland areas that experience moderate corrosion will benefit from Class 3 fasteners, though Class 4 options provide added security for regions closer to industrial activities or coastal influences.
• For C2 Zones (Low Corrosion): In dry, arid regions, Class 3 fasteners are typically sufficient to ensure long-lasting performance. However, opting for Class 4 fasteners can provide extra durability in the event of unexpected weather changes or humidity increases.

Can South Africa’s Coastal Infrastructure Survive Corrosion?

The battle against corrosion is ongoing, particularly in South Africa’s coastal regions, where infrastructure is constantly exposed to harsh environmental conditions. As Coatings World discusses, the sustainability of coastal infrastructure depends on using the right materials and protective coatings to resist corrosion. Roofing fasteners, often overlooked, play a pivotal role in this battle. By choosing high-quality, corrosion-resistant fasteners, such as those recommended by Corroshield, builders and architects can ensure that roofing systems in even the harshest environments stand the test of time.

Conclusion

Corrosion is a formidable challenge in South Africa, especially in coastal and industrial regions. Understanding the corrosion zones and selecting the right roofing fasteners—whether Class 3 for moderate environments or Class 4 for extreme conditions—can make all the difference in prolonging the life of a roofing system. By using the correct fasteners, architects and engineers can ensure that their projects remain structurally sound, no matter the environment.

For more information on South Africa’s corrosion zones, you can refer to the detailed research by Sibiya L. on the atmospheric corrosivity map of South Africa, available here.

Need the best fastener solution for your roofing system? Contact Corroshield today for expert advice and to explore their range of corrosion-resistant fasteners. Whether you’re working in high-corrosion coastal zones or inland areas, Corroshield has the right fastener to ensure the longevity and stability of your roofing project.