Galvanic Corrosion Between Dissimilar Metals in Facades

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Galvanic corrosion occurs when two dissimilar metals are in electrical contact in the presence of moisture and an electrolyte, causing the less noble metal to corrode faster. In facades it is prevented by choosing compatible metals, isolating contact points with non-conductive barriers, and keeping water from bridging the joint.

What galvanic corrosion is

Galvanic corrosion is an electrochemical reaction. When two metals with different electrode potentials touch and a conductive film of water, condensation or salt is present, current flows between them. The less noble metal, called the anode, sacrifices itself and corrodes, while the more noble metal is protected.

The effect is strongest where the electrolyte is persistent, such as rain runoff, salt-laden coastal air or water trapped in a crevice. Dry, well-sealed joints rarely suffer, which is why detailing matters as much as material choice.

Metal pairings that need attention

Not every combination is a problem, but some pairings deserve a closer look in facade work:

Carbon steel or hot-dip galvanized steel fixed to stainless steel
Aluminum in direct contact with carbon steel or stainless steel
Copper or copper alloys draining onto aluminum or galvanized surfaces
Stainless steel fasteners in aluminum profiles without isolation

Check the relative position of each metal in a galvanic series table before specifying, and treat any pairing with a large separation as high risk.

Detailing connections to prevent corrosion

The most reliable protection is physical separation. Use non-conductive washers and sleeves, such as nylon, PTFE or neoprene, to isolate fixings from the more noble metal. Specify insulating tape or gaskets between aluminum and steel brackets.

Also design joints so water drains away and does not sit in the contact zone. Avoid lap joints that trap moisture, and provide weep paths or sealed overlaps where dissimilar metals meet.

Finishes and coatings as a barrier

Coatings help by breaking the electrical path. Hot-dip galvanizing gives steel a sacrificial zinc layer, and powder coating or anodizing can seal aluminum. However, coatings are only effective when they are undamaged, so specify coating at cut edges, drilled holes and welded zones.

Touch-up after installation is part of the detail. A scratched coating on one component can concentrate corrosion at the exposed spot, so plan for careful handling and repair.

Working with the fabricator early

Galvanic problems are easiest to solve in the drawing stage. Share the full list of materials, fixings and finishes with the fabricator so that isolation, fastener type and coating sequence can be coordinated. Mention the exposure conditions, including distance from the sea and wind-driven rain, because these change the risk.

Exact values for thickness, fastener grade and standard compliance should be confirmed with the structural or facade engineer for each project.

Maintenance and inspection over time

Even well-detailed facades need periodic checks. Inspect connection points for staining, white or rust-colored deposits and swollen coatings. Clean salt and debris from drainage paths, and reseal gaskets when they harden or crack.

Look at fixings and contact faces at regular intervals
Repair coating damage promptly
Keep drains and weep holes clear

Frequently asked questions

Can stainless steel and aluminum be used together on a facade?

They can, but the aluminum is more likely to corrode when in direct contact with stainless steel in wet conditions. Use isolating washers, sleeves or tape at every contact point.

Do I need isolation if the metals are painted or coated?

Coatings reduce the risk but do not remove it, especially where they are scratched or cut. Isolation at the contact point is still recommended for reliable long-term performance.

Is galvanic corrosion common in facades?

It is one of the most frequent causes of premature failure in metal connections when dissimilar metals are not detailed correctly. Good design and isolation prevent most cases.

Who should confirm the final connection details?

The architect and structural or facade engineer should confirm the details for each project, including materials, isolation method and fastener grade, before fabrication begins.

Common mistakes to avoid

Specifying different metals at the same joint without isolation, or leaving cut edges and drilled holes uncoated, are the most common causes of galvanic damage. Water that stays trapped in a crevice makes the problem worse.

Our recommendation

Specify isolation at every dissimilar metal contact, choose fasteners that match or are compatible with the parent metal, and design drainage so water never sits in the joint. Involve the fabricator before the drawings are final.

Summary

Galvanic corrosion between dissimilar metals is avoidable with compatible material choices, physical isolation, good drainage and protected coatings. Early coordination between architect and fabricator gives the most durable facade connections.

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