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You may be considering an aluminum deck, but do aluminum decks rust? It’s a question that we get asked often here at Wahoo Building Products, and it’s relevant. Many fear that your aluminum deck will eventually rust because aluminum is metal.  Even so, the fact of the matter is that aluminum decks do not rust.

How Rust Can Affect Aluminum

However, aluminum can corrode. First, let’s address how rust can affect aluminum and how to prevent it.  When oxygen comes in contact with iron-containing metals, it will eventually rust.  However, aluminum does not contain iron and, therefore, does not rust. If you see what seems to be rust on your aluminum, it is more likely a stain from a metal it has come into contact with.

Example

A common decking example of this happening would be if you used stainless steel fasteners on aluminum decks. The aluminum will not rust, but the steel fasteners might.  This could cause rust to stain the aluminum. The best way to prevent this is by using steel fasteners with a zinc coating. All of Wahoo Decks’ stainless steel fasteners have a zinc coating to prevent rusting. In the Galvanic series of metals and alloys, aluminum and Zinc are side by side. Therefore, zinc does not increase base metal corrosion and is safe to use with aluminum. However, rust and corrosion will occur if you use a stainless steel fastener without a zinc coating. When it comes to building with aluminum, always use stainless steel with a zinc coating to avoid staining.

How Can Aluminum Corrode

Now that we’ve answered the question of how rust can affect aluminum, it’s time to take a look at how aluminum can corrode.  Corrosion can happen in certain scenarios. To understand this, you need a better comprehension of the physics of aluminum and the process known as Galvanic Corrosion.

galvanic corrosion occurring between aluminum and copper“When two dissimilar metals are immersed in an electrolyte solution, a battery is created. The electrolyte solution serves as a bridge between the two metals and effectively closes half of an electrical loop. When the two dissimilar metals come into contact, the electrical loop is closed, and the natural voltage differential between them causes electron flow. One metal will become the anode (negative) and one will become the cathode (positive)” (Corrosion Resistance of Aluminum).

Galvanic Corrosion

Often Galvanic Corrosion occurs when aluminum comes in contact with a metal like copper in or near saltwater. Saltwater is a perfect example of an electrolyte solution. ACQ lumber is a very common decking board.  However, due to its high copper content, ACQ is corrosive to many metals, like aluminum.  The ACQs’ highly conductive copper, along with oxygen and rainwater, cause Galvanic Corrosion of the bare metals. Therefore, untreated, mill-finished steel or aluminum should not have intimate contact with ACQ-treated lumber for extended periods, especially in water. Remember that the corrosion severity will depend on the two metals in contact with one another.

If aluminum is the primary metal, the Galvanic Corrosion process takes many years to occur or may not even happen. If concrete is in contact with aluminum, Galvanic Corrosion will occur faster and be more severe.

Preventative Measures to Avoid Galvanic Corrosion

Using a rubber membrane along joists is an added protective step to take to prevent Galvanic Corrosion.

Using a rubber membrane along joists is an added protective step to take to prevent Galvanic Corrosion.

Use a Butyl rubber membrane deck protector on joists if the decking comes in contact with a product like pressure-treated wood. This is especially necessary if you are located near salt water. A Butyl rubber membrane is highly weather-resistant and flexible. In addition, use a rubber membrane when installing a deck on or near concrete to prevent Galvanic Corrosion from occurring.

Another preventative measure is to use a marine-grade alloy to begin with. There are way too many different aluminum to list.  Each one has different qualities and special uses. “It is imperative that the proper alloy is selected to realize aluminum’s reputation as highly corrosion-resistant metal in marine applications” (Corrosion Resistance of Aluminum).

How Wahoo Building Product’s products resist aluminum corrosion

  1. Wahoo Decks’ aluminum boards are watertight. This prevents water (electrolytes) from becoming the catalyst for Galvanic Corrosion.
  2. Wahoo Decks uses a 6005-T5 series marine grade aluminum with a polyester powder-coated finish, providing a protective barrier between dissimilar metals.
  3. All of Wahoo Decks’ stainless steel fasteners have a 410 Zinc coating. The Zinc coating prevents the fastener’s corrosion and protects against Galvanic Corrosion between the aluminum and the steel in the fastener.

About Wahoo Building Products:

Wahoo Building Products is a leading manufacturer of award-winning outdoor decking products. Our products have been engineered to be uniquely low maintenance and more resistant to natural elements than traditional decking products. Wahoo Decks offers AridDek, a waterproof aluminum decking product. DryJoistEZ, a revolutionary waterproof and structural exterior aluminum joist, and Wahoo Rail, a complete line of aluminum railing kits. Additional information about Wahoo Building Products can be found on www.WahooBuildingProducts.com or by calling (877) 270-2317.

Photo Credit:

Aluminum’s Corrosion Resistance

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