Building owners and architects are increasingly turning to zinc for its long, maintenance-free life and adaptability to various design styles ranging from traditional to modern.
Zinc is a natural material that never fades and retains its look over its entire life span. It is also a non-corrosive, environmentally friendly product with a 100% clear water runoff. Zinc’s anti-corrosion qualities have led zinc to be used extensively as a protective coating for steel and other metals.
Although zinc has been used in Europe for more than 200 years, it is relatively new to the North American market. However, it is quickly generating interest and is being chosen for use on a variety of buildings thanks to its natural beauty and myriad of attributes as a commercial building material.
One of those attributes is its longevity. Zinc sheets used in architecture for roofs and walls have an extremely long service life. In roof applications, for example, zinc sheets have an expected service life of 60 – 100 years depending on the geographic location. The service life is even more in wall applications.
Maintenance costs are minimal because zinc naturally develops a protective zinc carbonate layer or patina as it weathers and ages, eliminating the need for paints and other coatings. Because the metal is uncoated, there is no possibility of fading, chipping, peeling or chafing, which reduces overall life cycle costs. Moreover, as the patina forms, any scratches or imperfections in the metal tend to disappear.
The patina has an aesthetic effect as well, because as it develops, the natural matte gray color of the metal changes over time, varying somewhat in tone depending on building geometry and local climatic conditions and pollution levels. Architects say the color actually gets richer by imparting a grey-blue hue to the metal as it adapts to atmospheric conditions and blends with other building materials.
Malleability is another attribute of zinc. The metal is easily worked and formed to achieve a wide variety of complex shapes and intricate details. This capability is most evident in Europe where zinc is the most popular metal used in the manufacture of rainwater goods such as gutters and downspouts. It is also used to produce building accessories such as gargoyles and other types of decorative ornaments.
Like all metals, zinc used in roof and wall applications is 100 percent recyclable. In fact, over 30 percent of the world’s zinc used in all applications comes from recycled zinc products, a figure that is expected to increase as demand for zinc continues to grow. In addition, the amount of energy used to produce zinc from ore is the lowest of all non-ferrous metals. Energy consumption is even lower when zinc is produced from recycled material.
Compared to steel and copper, natural zinc is soft, but by combining it with titanium, copper and aluminum, the resulting alloy, commonly called zinc alloy, can meet the demands of most commercial roof and wall applications. Titanium improves zinc’s tensile strength and hardness, copper imparts color and malleability, and aluminum hides the spangles commonly seen on galvanized hot-dipped surfaces.
Even though the zinc alloy is stronger than natural zinc, the alloy still retains the benefits of the natural metal, including such attributes as malleability, color, texture and the patina. As a result, the number of architectural applications where zinc may be used greatly expands, ranging from steep sloped roofs to metal composite wall panels.