Aluminium will corrode at the contact point whenever it touches a more noble metal in the presence of moisture. This is galvanic corrosion - also called dissimilar metal corrosion - and it is one of the most preventable causes of facade deterioration in Australia.
The principle is straightforward. When two different metals are in direct contact and an electrolyte (water, salt spray, condensation) bridges them, the less noble metal gives up electrons and corrodes preferentially. Aluminium sits relatively low on the galvanic series, which means it is the metal that loses in most pairings.
Understanding which combinations are safe, which are risky, and how to isolate where needed will save you callbacks and protect the long-term performance of the facade.
Which combinations cause problems?
Not all metal-to-metal contact is equal. The further apart two metals sit on the galvanic series, the greater the driving force for corrosion.
High risk:
- Aluminium cladding in direct contact with mild steel brackets. This is the most common issue on site. Without isolation, the aluminium corrodes at the contact point - sometimes noticeably within months in coastal or industrial environments.
- Aluminium cladding in contact with copper flashings. Copper is highly cathodic relative to aluminium. The potential difference is large, and corrosion can be severe. This combination should always be avoided or fully isolated.
Lower risk, but not zero:
- Aluminium cladding with stainless steel fixings (grade 304 or 316). The potential difference is smaller than with mild steel, and the contact area of a screw or rivet is small relative to the cladding panel. In practice, this is generally acceptable - particularly with coated aluminium - but in aggressive environments (coastal, tropical, industrial) it is worth adding isolation as a precaution.
Which combinations are safe?
Aluminium on aluminium is the simplest answer. Same metal, no galvanic potential, no corrosion risk from the pairing itself. Valmond & Gibson’s conneQt aluminium subframe system is designed around this principle - when you fix interloQ or element13 panels to a conneQt subframe, the entire cladding-to-subframe assembly is a single-material system. No dissimilar metal interface, no isolation required.
Aluminium on galvanised steel with an isolation barrier is also a reliable combination. The zinc galvanising reduces the potential difference, and a simple isolator closes the remaining gap.
How do you isolate where needed?
Isolation does not need to be complicated. The goal is to prevent direct metal-to-metal contact and to stop moisture bridging between the two surfaces.
Common methods that work well in facade assemblies:
- Nylon or EPDM washers and bushings between fasteners and the opposing metal. These are cheap, readily available, and effective.
- Isolating tape or isolating paint applied at bracket-to-cladding contact surfaces.
- Neoprene pads between brackets and panels, which also help with thermal and acoustic bridging.
- Aluminium fasteners where the fixing specification allows. Both interloQ and element13 can be installed with aluminium rivets, keeping the entire assembly in one metal.
The important thing is that the barrier is continuous at the contact surface. A washer under the head of a screw does not help if the shank is still touching bare aluminium.
What about run-off corrosion?
Direct contact is not the only pathway. Water running off one metal and onto another can carry dissolved ions that cause staining and surface corrosion on the downstream material - even without the two metals ever touching.
The most common culprits are copper pipes, weathered steel features, and lead flashings. If water from any of these drains across aluminium cladding, expect discolouration and pitting over time.
Plan drainage paths during design. Where dissimilar metals are unavoidable on the same elevation, ensure water sheds away from the aluminium, not across it.
Where does environment matter most?
Galvanic corrosion requires an electrolyte. In dry inland environments, the risk from minor dissimilar metal contact is low. In coastal areas with salt spray, tropical regions with persistent humidity, or industrial zones with airborne pollutants, the electrolyte is always present and the corrosion rate increases significantly.
In these environments, be more rigorous with isolation - even on combinations that might be acceptable in milder conditions.
Regular cleaning also helps. A quarterly wash removes salt and pollutant deposits from aluminium surfaces, eliminating the electrolyte film that accelerates corrosion between maintenance cycles.
The practical takeaway
Most dissimilar metal corrosion in facade assemblies is avoidable with simple, low-cost measures. Use aluminium-on-aluminium where you can. Isolate where you cannot. Plan drainage paths so run-off from other metals does not cross your cladding. And in aggressive environments, treat every metal interface as one that needs attention.
The 165CW curtain wall system, interloQ rainscreen, and element13 panel systems all use aluminium as the primary material. Pairing these with conneQt aluminium subframing keeps the assembly in a single metal family - the most reliable way to eliminate galvanic corrosion risk from the facade envelope entirely.
Related Reading
- Subframe Design for Aluminium Rainscreen Cladding
- Aluminium Facades in Coastal Environments: Corrosion, Durability, and Specification
- Aluminium Facade Maintenance: A Practical Guide for Building Owners
- Aluminium Extrusion Alloys Explained: 6060 vs 6063 vs 6005A
Last updated: 4 April 2026