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Galvanic Corrosion: What It Is and How to Prevent It
When working with metal fasteners in construction — especially in coastal, humid, or mixed-metal environments — galvanic corrosion is a real threat that can cause premature failure, unsightly rust, and long-term structural issues.
At Builders Stainless, we specialize in stainless steel fasteners and hardware. But even stainless can contribute to corrosion if it’s paired with incompatible materials.
In this guide, we’ll explain:
• What galvanic corrosion is
• Why it happens
• Which materials are most at risk
• How to prevent it in decks, railings, fences, enclosures, and more
What Is Galvanic Corrosion?
Galvanic corrosion occurs when two dissimilar metals are in contact with each other in the presence of an electrolyte (like water, especially saltwater). The less noble metal becomes the “anode” and will corrode faster, while the more noble metal (like stainless steel) acts as the “cathode” and remains unaffected.
In other words: When stainless steel fasteners touch galvanized steel, aluminum, or zinc, those other metals can corrode even faster than they normally would.
Common Problem Scenarios
Here are real-world places where galvanic corrosion shows up:
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Stainless Screws in Galvanized Joist Hangers
• The zinc coating corrodes rapidly around the screw heads
• Causes discoloration, streaking, or total hardware failure
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Stainless Cable Hardware on Aluminum Posts
• Aluminum begins to pit, corrode, or oxidize at contact points
• Especially problematic in coastal decks and railings
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Mixing 410SS Screws with Coated Steel or Brass
• The wrong fastener pairing can cause discoloration or fastener decay
• Especially with concrete, wet wood, or chemically treated lumber
What Metals Are Most at Risk?
Corrosion Risk When in Contact with Stainless:
Zinc (galvanized steel)
Very high — fast corrosion likely
Aluminum
High in wet or salty environments
Carbon steel
Moderate risk, especially with moisture
Brass or copper
Minor — but can still stain or pit
Another stainless grade
Safe if grade is compatible
5 Ways to Prevent Galvanic Corrosion
1. Use the Same Metal Whenever Possible
The best way to avoid galvanic corrosion? Don’t mix metals. If you’re using stainless steel fasteners, try to pair them with stainless connectors, brackets, or anchors.At Builders Stainless, we sell only stainless hardware to avoid compatibility issues altogether.
2. Use Plastic or Nylon Isolators
When you have to mix metals (like mounting stainless onto aluminum posts), insert plastic washers, bushings, or sleeves to create a physical barrier between the metals.
This stops the electric current that causes corrosion.
3. Seal Contact Points
Apply corrosion-inhibiting compounds or sealants where two metals meet. This limits the moisture that acts as the electrolyte and slows down corrosion.
Example products:
• Dielectric grease
• Tef-Gel or Lanocote
• Anti-seize compounds with insulating properties
4. Use the Right Grade of Stainless
Some stainless grades, like 316, are much better for wet, coastal, or chemically exposed environments. 410SS (while strong and magnetic) has less corrosion resistance and can worsen galvanic interactions if not paired carefully.
Need help? Contact us — we’ll recommend the best fastener for your material combo.
5. Design for Drainage & Dryness
Galvanic corrosion needs an electrolyte — usually trapped water. Ensure water doesn’t pool around fasteners or connections.
Best practices:
• Drill drainage holes
• Use stainless spacers
• Avoid tight joints that trap moisture
Pro Tip: Galvanic Corrosion Happens Faster on the Coast
Saltwater = Electrolyte on steroids.
In coastal regions like Florida, galvanic corrosion accelerates dramatically. Stainless steel is the only reliable material for decks, railings, fencing, and outdoor enclosures.
But even stainless needs to be used smartly — and with compatible materials.
Your Stainless Steel Experts
At Builders Stainless, we help builders, contractors, and fabricators avoid costly corrosion mistakes. We stock only marine-grade stainless hardware and will always guide you to the safest, most durable option.
Need help avoiding galvanic corrosion in your next build? Contact us here, or explore our corrosion-resistant products below:
