Metal contractors have found that going back to the basics and using Earth’s raw resources is beneficial in terms of cost and design. Zinc, aluminum and copper are naturally resistant to the elements without added coatings and finishes, contain high levels of recycled content and are fully recyclable at the end of their useful lives. Natural metals also are more malleable than their manufactured counterparts, providing architects with design flexibility for complex shapes and intimate details.

Credit: Rheinzink America, Inc.

ZINC
The world naturally is abundant in zinc; it’s the 27th most common element in the Earth’s crust. Worldwide, more than 7 million tons (6.4 metric tons) is mined or recycled annually. Although Europe has been using zinc for 200 years, only recently has North America adopted the metal for its myriad benefits:

  • Zinc roofs have an expected lifespan of 60 to 100 years; zinc-coated steel poles placed in the Australian Outback more than 100 years ago still are in excellent condition.
  • Zinc is a soft metal; when it’s combined with titanium, copper and aluminum, the resulting alloy can meet the demands of most commercial wall and roof applications while still retaining the benefits of the natural metal.
  • The naturally developing patina has aesthetic and practical benefits. The matte-gray color of zinc changes over time to a gray-blue hue as the metal adapts to atmospheric conditions and blends with other building materials.

ALUMINUM
As the third most abundant element on the planet, behind only oxygen and silicon, aluminum still is a relatively new discovery; Sir Humphrey Davey discovered it in 1808. Aluminum wasn’t commercially produced until 1888. More than 3 billion pounds (1.4 billion kg) of aluminum is used annually in construction in the U.S. Most aluminum used in construction can be found in roof and wall systems on commercial buildings. Aluminum can provide a building with many benefits.

  • In low- and steep-slope roofing, aluminum’s ability to deflect the sun’s rays results in less heat transfer to the building’s interior for lower energy costs.
  • Large aluminum wall panels, flat or formed, require fewer joints for fast, economical installation in new and retrofit applications.
  • Aluminum’s light weight requires less structure to support the building’s weight. Buildings in seismic zones benefit because seismic forces are proportional to the weight of the structure.

COPPER
Copper enjoys a rich history. For nearly 5,000 years, it was the only metal known to man. In Rome, the copper cornice around the dome at the Pantheon lasted more than 1,800 years. The copper roof on Christ Church, Philadelphia, was installed in 1742 and is the oldest copper roof in the U.S. Long life isn’t the only driving force behind copper, though.

  • As copper ages, it develops from its natural color that resembles a penny through a progression of browns and grays to a final blue-green or graygreen patina.
  • Once only used on roofs, copper now is accepted as wall cladding. The trend is driven by European influence and began about a decade ago.
  • Consumption of copper for roofing has risen an average of 8 percent per year since 1992. Known worldwide resources of copper are estimated at about 5.8 trillion pounds (2.6 trillion kg). About 0.7 trillion pounds (0.3 trillion kg), or 12 percent of that number, previously has been mined and still is in circulation because of copper’s high recycling rate.

RESOURCES