My first experience with aluminum was in welding school. When attempting an aluminum weld I forgot to reverse the polarity on my machine. The result was that I vaporized most of two pieces of aluminum. Electrical current normally flows from positive to negative (ground), but welding aluminum requires the opposite. On my second attempt, I ended up looking through a giant hole I had burned at a swiftly-cooling smear of aluminum foil on the floor. Aluminum doesn’t glow red when it approaches its melting point, and I had inadvertently heated nearly the whole workpiece to its melting point without realizing it.

These experiences with aluminum really drove home for me how different this metal is from steel, to the point where directly comparing the two can be misleading. When it comes to deciding between steel railing and aluminum railing systems for decks, you need to judge aluminum on its own merits.

Dispelling Myths About Aluminum

As an element, aluminum isn’t at all rare. It makes up 8.53% of the Earth’s crust to iron’s 5.63%. Aluminum’s greater expense and rarity when compared to steel is due to two factors. It is a reactive element that bonds to many other elements easily, especially when heated, and it can only be separated back into its pure metallic form by jolting it with huge amounts of electricity. That means that producing aluminum in usable quantities wasn’t possible until electricity was widely available.

Many guides comparing aluminum to steel will claim that aluminum doesn’t corrode. But this characteristic--usually touted as aluminum’s greatest strength--isn’t actually true. Aluminum actually does form aluminum oxide. It differs from rust (iron oxide) in that aluminum oxide forms a surface layer that prevents oxygen from getting at the aluminum underneath, preserving the rest of the metal. Rust, on the other hand, actually opens up iron or steel’s molecular structure to further intrusion by oxygen in the air. Essentially, this means aluminum will corrode to a certain point, then stop, while rust, once started, will just keep going.

The Strengths of Aluminum Railing Systems for Decks

In my opinion, aluminum really shines because of its unique qualities--those things that it doesn’t have in common with many other metals, and which set it apart from steel as something totally different. These unique qualities include:

• Lightness: Because aluminum is less dense than steel, it is also lighter. A single laborer cannot lift a 16-foot-long hollow piece of 6x6 steel tubing by himself, but he can lift the aluminum equivalent. This is worth considering when you’re looking into DIYing your deck railing, because when several separate pieces of metal are joined together--as in a railing section--the weight is multiplied.
• Resistance to corrosion: As I mentioned before, aluminum is much less likely to undergo damaging corrosion than steel is, and if corrosion does form, it won’t spread in the same way as rust.
• Unique thermal properties: In cold weather, steel grows more brittle while aluminum actually gets stronger. Aluminum is also an incredible thermal conductor, with a thermal conductivity of 205 to mild steel’s 43 at room temperature. What this means is that aluminum may absorb heat quickly, but it will disperse it just as quickly.

These unique properties translate to easier installation (due to aluminum’s lightness) and more durability than steel in certain scenarios. If you envision a railing in a heavy wind, the greatest strain will be on the points where that railing is anchored at the sides and base. For railings made of a light metal like aluminum, less force will be exerted on those anchor points, and it is less likely that the fasteners anchoring the railings will break.

As for aluminum’s unique thermal properties, they mean that even if an aluminum railing is out in the sun all day, it probably won’t get hot enough to be uncomfortable to the touch. And since aluminum actually gets stronger as it gets colder, this metal is a perfect choice for locations with temperature extremes, such as desert conditions where temperatures can swing from extreme heat to extreme cold within a 24-hour period.

When Should You Choose Aluminum?

Steel and aluminum are often treated as siblings competing for validation, but an analogy that is closer to the truth might describe them as third cousins once removed. They are very different metals, and being familiar with one doesn’t prepare you to work with the other.

So when should you take the plunge and go for aluminum railings? In most situations, steel that’s well protected from the elements will be cheaper and will do the job just fine, but when weight, extreme cold, or extreme variations in day and night temperatures are factors then the extra expense for aluminum railings is justified. Aluminum may also be a good choice when you’re looking for a railing that won’t rust in a rainy, humid environment. Knowing when aluminum is worth it is largely a matter of being familiar enough with the metal to know if its unique properties will be an advantage. You’ll also want to look for a railing system that is engineered thoughtfully, to work with aluminum’s special qualities.

One system like this is the Al¹³ PLUS system of aluminum railings from Fortress Building Products. This is a pre-welded railing system that comes in several finishes--like black sand, gloss black, and white--and is protected by a high-quality powder coat for extra resistance against corrosion. It’s an easy-to-install railing system as well, using brackets that install with the use of matching, coated, cutting screws. This attention to detail is a hallmark of all of Fortress Building Products’ offerings, from railings to decks to fences.