You may be considering an aluminum deck but are wondering, do aluminum decks rust? It’s a question that we get asked often here at Wahoo Decks and it’s a relevant question. Many fear that because aluminum is metal your  aluminum deck will eventually rust.  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 actually affect aluminum and what you can do 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 of preventing this from happening 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 corrosion of the base metal and is safe to use with aluminum. However, if you use a stainless steel fastener without a zinc coating, rust and corrosion will occur. 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 takes place 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 rain water cause Galvanic Corrosion of the bare metals. Therefore, untreated, mill finish steel or aluminum should not have intimate contact with ACQ treated lumber for extended periods of time, especially in the presence of water. Keep in mind, the severity of corrosion will depend on the two metals that are 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 at a faster rate and will be more severe.

galvanic corrosion on aluminum

In this particular case, Galvanic Corrosion took place on an aluminum rail post. Inside the aluminum post was a steel bolt that began to corrode once the post was in contact with saltwater

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  saltwater. 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 occurring.

Another preventative measure is to use a marine grade alloy to begin with. There are way too many different aluminums 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 Decks’ 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; the finish provides a protective barrier between dissimilar metals.
  3. All of Wahoo Decks’ stainless steel fasteners have a 410 Zinc coating. The Zinc coating prevents the corrosion of the fastener and also protects against a Galvanic Corrosion between the aluminum and the steel in the fastener.

About Wahoo Decks:

Wahoo Decks 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 Decks can be found on www.WahooDecks.com or by calling (877) 270-2317.

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Aluminum’s Corrosion Resistance