Corrosion continues to pose a serious challenge for architects and builders. The Australasian Corrosion Association estimates corrosion costs the Australian economy roughly $78 billion every year. Costs include structural damage and the major remediation of works.
Fortunately, much of that loss can be avoided. It starts with better designs that avoid the chance of corrosion and choosing materials more wisely for long-term durability and performance.
Corrosion is the gradual breakdown of a material, typically metal, caused by chemical or electrochemical reactions with its surrounding environment. The important thing to understand is that refined metals are unstable by nature. Over time, they try to revert to a more stable, oxidised form. In the case of iron, that means rust.
Corrosivity refers to how aggressively an environment can degrade materials. It’s measured by the rate of deterioration over time and is a critical factor when assessing site conditions. The more corrosive the environment, the more durable your material choices need to be.
While corrosion can’t be eliminated, especially on exposed or untreated metals, it can be slowed dramatically through smart design. That means looking beyond individual components and considering how materials interact as a system. How do components work with one another? Where are the vulnerabilities? This kind of holistic thinking is key to achieving long-term performance.
Galvanic corrosion happens when two dissimilar metals touch while exposed to an electrolyte, such as saltwater. Because each metal has its own level of corrosion resistance or nobility, one becomes more vulnerable. The less noble metal (the anode) begins to corrode in favour of the more noble one (the cathode), setting off a galvanic current similar to what powers a battery.
Let’s take aluminium as an example. On its own, it’s quite corrosion-resistant, but bolt it to steel and expose the pair to saltwater, and the aluminium will deteriorate quickly. The bigger the gap in nobility between the metals, the faster the damage sets in. To assess compatibility, consult a Galvanic Series Table.
Crevice corrosion arises when water gets trapped between surfaces, forming a stagnant zone where localised corrosion thrives. It’s a hidden risk, often found behind washers, gaskets or beneath paint films – areas where inspection is difficult until it’s too late.
Uniform corrosion causes material to wear away evenly across a surface, usually from ongoing exposure to oxygen and moisture. It’s a slow, steady process. One of the most familiar examples is untreated mild steel left out in the open – it gradually weathers and thins as oxidation takes hold.
Coastal zones present the highest risk due to the presence of airborne salt. Accordingly, the Australian Standard AS 4312 categorises corrosivity into six zones:
Environmental corrosivity is assessed using ISO 9223, which tests material loss over a year using standardised metal plates. For instance, a C2 zone might show <25 microns of loss annually, while a C4 environment could exceed 80 microns.
Other aggressive environments include:
Each project site is unique. This is why a comprehensive approach is essential when determining how corrosion can be prevented in architectural design.
| First year corrosive rate of metals µm/year | |||||
|---|---|---|---|---|---|
| ISO 9223 Category | Corrosivity | Carbon Steel | Zinc | Copper | Typical Environment |
| C1 | Very Low | < 1.3 | < 0.1 | < 0.1 | Dry Indoors* |
| C2 | Low | 1.3 – 25 | 0.1 – 0.7 | 0.1 – 0.6 | Arid/Urban Inland |
| C3 | Medium | 25 – 50 | 0.7 – 2.1 | 0.6 – 1.3 | Coastal or Light Industrial |
| C4 | High | 50 – 80 | 2.1 – 4.2 | 1.3 – 2.8 | Sea-shore (calm) |
| C5 | Very High | 80 – 200 | 4.2 – 8.4 | 2.8 – 5.6 | Sea-shore (surf) |
| CX | Extreme | 200 – 700 | 8.4 – 25 | 5.6 – 10 | Shoreline (severe surf) |
| * Some indoor environments like swimming pools may be classified as C5 or extreme due to humidity, prolonged wetness and contact with chemicals such as chlorine used in pools. | |||||
One of the most effective ways to fight corrosion is to alter the surface itself. Harden it. Shield it. Make it tougher to penetrate. Surface treatments like plating, galvanising, anodising or powder coating can significantly boost resistance.
Material choice matters too. Opt for corrosion-resistant options such as stainless steel or coated aluminium where possible.
Even small adjustments make a difference. Something as straightforward as adding a nylon washer between two dissimilar metals can interrupt the electrical flow that triggers galvanic corrosion.
Ultimately, the question is: how can corrosion be prevented in architecture? It starts with thoughtful design. Small decisions, like specifying corrosion-resistant materials, avoiding crevices or breaking up dissimilar metals, can dramatically extend the lifespan of your project.
Explore our products to find architectural systems that combine visual appeal with long-term durability.
For architects focused on durability, material choice is crucial. Popular options include:
At Sculptform, our aluminium and timber battens, screens and aluminium cladding are engineered with corrosion resistance in mind — designed to perform in even the harshest conditions.
Explore our range of corrosion-resistant architectural solutions or contact us to discuss your project’s unique environmental challenges and performance requirements.
