BEST METALS FOR EXTERIOR ARCHITECTURE | CORROSION-RESISTANT METALS

The oceanfront is a beautiful but expensive place to live. And as it turns out, it’s also one of the most difficult places to use metal in outdoor architecture. 

The salt and moisture of the seaside makes long-lasting construction a challenge. The majority of coastal buildings need maintenance every few decades or, depending on the metal used in their construction, they may need to be completely replaced.

And while most metals are resistant to corrosion, they are not immune. Those that are immune to corrosion are typically luxury metals that carry big price tags.

As you move further inland, all metals survive longer thanks to lower levels of salt in the environment. It won’t save them from the rain and weather, but they stand a better chance.

No matter where you build, your architecture will be exposed to wind, rain, and possibly salt and other elements.

Deciding on the best metals for exterior applications can be the difference between a long-lasting tribute to your skill and an ugly, costly failure. Here are some of the best metals for outdoor use.

THE 4 BEST, MOST CORROSION-RESISTANT METALS FOR EXTERIOR ARCHITECTURE

So, which architectural metals are best for exterior architecture?

Stainless steel -- steel with a chromium oxide layer that lets it shine

Red metals (brass, copper, bronze) -- luxury metals for the fancy

Aluminum -- common in outdoor fixtures and more

Galvanized steel -- carbon steel coated in liquid zinc as added protection from corrosion

Now let’s compare these metals through the qualities that matter most to you: price, dependability, and beauty. Let’s start with the most common, yet least durable: galvanized steel.

4.  Galvanized Steel

Galvanized steel is the least corrosion-resistant metal on this list. Galvanized steel is more about function than beauty, so it’s not your best choice if looks matter for your project. Despite that, it is most commonly used because it offers at least 50 years of strong, affordable performance (25 or more in saltwater environments).

Galvanized steel is carbon steel that is coated in liquid zinc. The zinc becomes the sacrificial anode and will corrode before the steel underneath, even if some of the steel is exposed (a phenomenon called preferential corrosion). 

One benefit of galvanized steel is the ability to adjust the amount of protection by specifying the amount of zinc deposited on the surface of the steel during its production. The more zinc you put on, the better protection you will get!

Galvanized steel is by far the most affordable on this list, which is why it remains so widely used outdoors. Some of the most common galvanized items we produce are components used to mount solar panels to commercial building roofs.

So, galvanized steel is best for projects that only need short-term corrosion resistance, or architecture that requires planned, consistent renovations.

(Related post: Don't Get Salty About Coastal Construction - Use These Architectural Metals)

3.  Aluminum

One step above galvanized steel is aluminum. Common outdoor aluminum products include light fixtures and door and window frames.

Does aluminum rust? Nope -- it creates its own protective coating through a process called self-passivation. As aluminum oxidizes, it creates a protective layer around itself like a snail drawing into its shell. Any paint on it will fade quite a bit.

Manufacturers can force this process via anodizing, which immediately strengthens the metal and leaves it with a polished finish.

Aluminum moulding trim for exterior use is most often shaped through extrusion, though we roll form plenty of it. It is often used on the exterior framing of storefront doors and windows.

Depending on who you talk to, aluminum will last anywhere from 10s to 100s of years before decomposing. (We lean toward the former.) Remember that aluminum outdoor products are designed to be sellable at an economical price -- in many cases they're simply not going to last a long time outdoors.

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