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Copper Aesthetics

Finding the right wall cladding material for corrosive environments

Cda Case Study 1
325 Kent Avenue. Photo courtesy of SHoP Architects.

In today’s architectural environment, there are so many wall cladding choices that just finding a place to start can seem overwhelming. As the market continues its transition to an aesthetics-dominated state, the competition between wall cladding materials has gone into overdrive as architects break from their go-to options in search of a material that has remarkable visual traits and long-term value.

When it comes to wall cladding, just being a durable material isn’t good enough anymore. The first layer, or the “skin” of a building, needs to exemplify modern design and beauty, too. Unfortunately for many materials, it doesn’t take any specialized architectural talent to notice decay—especially corrosion. When professionals are seeking that “magic,” mesmeric material that’s tough in corrosive environments, they need to consider man’s first metal: copper.

Why Corrosion Threatens Building Exteriors

Corrosion is a particularly notable architectural threat because the chemical event can take many different forms and it can be horribly unsightly, and if not addressed, can compromise façade assemblies. Corrosion is a natural process where refined metals convert to their more chemically stable form, this can be the metal’s oxide, hydroxide or sulfide; an example of this is steel rusting. Over time this will gradually destroy a material, some far quicker than others, but in terms of aesthetics there can be unfortunate consequences.

Corrosion is unavoidable and can be caused by chemical (galvanic) or atmospheric symptoms, with the latter being more common. This can include pollution, smog, dust, salt exposure from the ocean or exposure to deicing solutions, contamination by human error, moisture buildup and really all forms of weather. Many materials may be used for wall cladding, but the question architects must answer is, “does the material have aesthetic durability or will it instead be an aesthetic liability down the road?”

Biomedical Sciences Partnership Building. Photo courtesy of CO Architects.

Checkmate Corrosion with Copper

When it comes to aesthetic durability there are few materials that can rival copper’s natural qualities, making it ideal for wall cladding installations. Copper is different because it becomes naturally resistant to corrosion as it ages. When exposed to the environment, copper forms an extremely durable oxide/sulfate layer that resists corrosion almost indefinitely. This layer, or patina, is completely harmless to the metal but is extremely resistant to atmospheric threats.

Not only does the patina stop corrosion, it also creates an evolving beauty. A patina changes copper’s color over time, displaying a stunning transformation from the classic salmon pink/orange, to muted brown, and then a mature greenish-blue in many regions of North America. Even in harsh environments like industrial areas, copper’s naturally occurring patina inhibits corrosion that is structurally damaging and visually unpleasant.

Copper and its alloys (nickeled-silver, bronze, brass and more) generally require no maintenance or special treatment. Once copper is installed it can be left alone for around the next 100 years, providing peace-of-mind and a cost-effective lifecycle. For example, the Statue of Liberty was erected in 1886 and is one of America’s most iconic cultural sites and perhaps the most well-known copper statue in the world. It took 100 years of New York City’s salty air, smog and East Coast weather before restorative work was finally needed on Lady Liberty in 1986.

Holbrook PreK-12 School. Photo: Robert Benson Photography.

Aesthetic Durability

Across North America firms like SHoP Architects, GEC Architecture, Flansburgh Architects and more are joining the trend and installing copper wall cladding systems for their aesthetic appeal and unsurpassed durability. It’s become so popular, that roughly half of the submissions to the 2018 North American Copper in Architecture (NACIA) Awards were wall cladding systems, a dramatic increase from a decade ago. It’s becoming well-known in the industry that when it comes to wall cladding, copper is simply hard to beat.


Stephen Knapp is the program manager of the Sheet, Strip, and Plate Council for the Copper Development Association Inc., and the executive director of the Canadian Copper & Brass Development Association. He also is involved with guiding the market development and promotional efforts for a wide variety of copper and copper alloy applications. To learn more, visit www.copper.org.