Upgrading an aging staircase is one of the most effective ways to improve facility safety, and retrofitting existing steel stair stringers with aluminum STEADY-STEP Anti-Slip Stair Treads is a very common use case for our customers.
However, mixing metals requires a bit of planning. You cannot weld aluminum to steel, meaning mechanical fastening is the only way to go. More importantly, bolting bare aluminum directly to bare steel creates a chemical reaction that can degrade your brand-new treads over time.
Here is exactly how to execute this retrofit safely, securely, and permanently.
The Hardware: Mechanical Fastening
Since welding is off the table, you need heavy-duty mechanical fasteners. We recommend 3/8” diameter stainless steel hardware for the best balance of strength and weather resistance.
For each mounting point, you will need:
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3/8” Hex head bolt
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3/8” Flat washer
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3/8” Split lock washer
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3/8” Hex nut
The Hidden Enemy: Galvanic Corrosion
When two dissimilar metals physically touch in the presence of an electrolyte (like rainwater, snowmelt, or even high humidity), it creates a microscopic battery. This process is called galvanic corrosion.
In this pairing, the aluminum stair tread acts as the anode (the sacrificial metal), and the steel stringer acts as the cathode. If left unprotected, the steel will literally pull electrons from the aluminum, causing the end plates of your STEADY-STEP treads to corrode and weaken over time.
Fortunately, preventing this is simple: you just have to stop the metals from touching.
3 Ways to Isolate Your Treads
By placing a non-conductive, insulating barrier between the aluminum end plate and the steel stringer, you break the electrical circuit and completely halt galvanic corrosion. Here are three effective ways to do it:
1. Galvanic Isolation Tape
One of the easiest and cleanest methods is to use a specialized galvanic isolation tape (such as those made by Heskins).
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How to apply: Cut the tape to size and apply it directly to the outside face of the aluminum end plates before maneuvering the tread into place.
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Pros: Easy to apply, zero gap created, and ensures 100% surface coverage.
2. The Nylon "Stand-Off" Washer
If you want to physically space the tread away from the stringer, a thick nylon washer (with an inside diameter of ~3/8") works perfectly.
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How to apply: Sandwich the nylon washer between the stringer and the tread end plate by sliding it onto the bolt during installation.
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Pros: Creates a slight physical "stand-off" gap that allows water and debris to wash straight through, reducing moisture buildup.
3. EPDM or Neoprene Gaskets (Bonus Option)
For heavy-duty industrial or highly corrosive environments (like coastal areas), you can cut custom squares of 1/16" or 1/8" EPDM rubber or Neoprene.
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How to apply: Punch a 3/8" hole in the center and use it exactly like the nylon washer.
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Pros: Rubber compresses slightly when bolted down, creating a watertight seal around the bolt hole that prevents water from weeping into the joint.
Pro-Tip: Isolating the Fasteners Stainless steel is also dissimilar to aluminum. While the corrosion risk is much lower than steel-to-aluminum, you can eliminate it entirely by using a nylon shoulder washer (a washer with a small sleeve) on the inside of the aluminum tread to prevent the stainless steel bolt threads and flat washer from touching the bare aluminum.
The Perfect Installation Stack
When you are ready to bolt the treads in place, assemble the hardware in this exact order from the outside in:
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Hex Head Bolt: Inserted from the outside of the steel stringer.
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Steel Stringer: The existing stair frame.
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The Isolator: Your chosen barrier (Galvanic Tape, Nylon Washer, or Rubber Gasket).
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STEADY-STEP End Plate: The side of your new aluminum tread.
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Flat Washer: Placed on the inside of the tread.
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Split Lock Washer: To prevent loosening from foot-traffic vibration.
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Hex Nut: Tightened securely.
By taking a few extra minutes to properly isolate your metals, your new STEADY-STEP Anti-Slip Stair Treads should last a lifetime.
Questions about your specific use case? Reach out to us anytime and we can help.