Copper Facts: Copper in Architecture

Copper has played an important role in the design and architecture of all types of structures for thousands of years. In ancient Egypt, the massive doors to the temple of Amen-Re at Karnak were clad with copper. The 162-foot-tall, nine-story Loha Maha Paya temple built in the third century B.C. in Sri Lanka sparkled with copper roof shingles. Copper was an integral part of European medieval architecture and today, some 10,000 years after it was first discovered by mankind, architects and building designers are finding new and innovative ways to use copper in their designs.

In most of the country, copper weathers naturally to a lovely blue-green color, or patina, over time. In arid climates, the color change is usually to a nut brown. The color-change is the result of surface oxidation caused mainly by moisture and corrosive elements in the atmosphere. Unlike rust oxidation, the copper patina is a protective barrier that retards further corrosion, to maintain copper's long life.

Not everyone can wait for copper to weather naturally. Demand from architects and builders for prepatinated copper products has prompted copper mills to develop new methods that speed up or replicate the natural aging process. Researchers are continually experimenting with ways to "enhance" this natural chemical conversion process. Aftermarket treatments offer a spectrum of patina color finishes, helping to create new markets - and make architectural clients happy.

From the spires and roofs of the celebrated castles and cathedrals of Europe to the solid copper "Golden Temple" in Kunming, China, or the famous baptistery doors of Italy's Florence Cathedral, copper and its alloys, bronze and brass, have continued to serve as decorative and functional elements on some of the world's oldest and most famous architecture.

Historic Christ Church in Philadelphia is the oldest-known copper-roofed church in America, dating back to 1727. However, the most enduring copper icon in U.S. history is the Statue of Liberty in New York Harbor, sculpted in 1884 from over 160,000 pounds of the semi-precious metal.

Various estimates put the lifespan of a copper roof at more than 100 years, while asphalt shingles - the most commonly used roofing material in America - are said to last 15-30 years, on average. This makes copper one of the most cost-effective roofing materials on the market. The reason for copper's longevity is the natural patina it develops with age that serves as a protective shell when the metal is exposed to the elements.

Beneath the gilded statues and weathervanes on Boston's Old State House and Faneuil Hall are copper forms. When the gilding wore away, the copper bases were found in excellent condition, allowing them to be easily regilded. The copper embellishments on the Old State House are a lion, a unicorn, an eagle, two scrolls and a banner-type weathervane. Atop nearby Faneuil Hall is its trademark, a copper weathervane in the shape of a grasshopper. In addition to the statues and weathervanes, there's a ton more copper in the State House's gilded cupola and decorative filigree around its clock and in the tower and dome on Faneuil Hall.

Copper is both literally and figuratively a green building material. Besides its familiar green patina, the metal is environmentally friendly, boasting one of the highest recycling rates of any engineering metal. And, copper roofing or cladding will never be discarded or wind up in a landfill. Instead, because of its value, it can be salvaged and recycled.

It would be difficult to imagine houses of worship without copper, brass or bronze. The aesthetic and durable metals are found in interior as well as exterior uses and often used for sacred vessels, statuary and decoration - and even most church bells rely on bronze (modern, electronic chimes rely on copper-wired circuits).

Sheet copper is available in many varieties: colors, coatings, textures and even pre-patinated for those who can't wait for nature to take its course. And, as architects are quick to point out, it can be applied in a number of ways: standing seam, batten seam, flat seam, shingles and other imaginative and attractive forms. Thousands of examples abound here in the USA and abroad.

A copper composite material composed of rigid thermoplastic sheets clad on both sides with copper sheeting is finding growing application for both building exteriors and interiors. Structures can now be clad with appealing copper, but with much less weight. The 4-mm thick composites weigh about two pounds per square foot, or only 35% as much as solid copper of that thickness. A stunning example of the material is the headquarters of the Ceridian Corporation in Bloomington, Minnesota.

Standing seam copper roofing is rated for resistance to the highest winds in Underwriters Laboratories' tests (UL-90). Each year high winds cause billions of dollars of damage to buildings. Now architects and contractors have a benchmark specification for roofing that meets the most demanding wind conditions.

Copper is used to roof ten major buildings at the U.S. training center for Olympic athletes near in Chula Vista, California. It is also used for plumbing, flashing, gutters and downspouts. The copper rolls and sheeting used for the architectural applications were donated by member companies of the Copper Development Association.

Roofing manufacturers use granules containing copper oxide in their asphalt shingles to prevent ugly discoloration of their product by algae. Copper ions, which inhibit algae growth, are leached by moisture from the porous ceramic granules, which can last for 25 to 30 years.

Shingles stained with unsightly algae have no copper in the roofing shingle granules to kill the roof algae. To remedy the problem, clean your roof with oxygen bleach and then install copper strips under roofing shingles to keep the black, streaky eyesore at bay. One strip, across the entire roof, having a two-inch exposure should protect 14 to 18 feet of the roof below it. To install, cut long 7- to 8-inch-wide strips of copper. Slide them up under the shingles until you hit the nails. Then, every four feet or so, lift a shingle tab and drive a copper nail through the copper strip. When you let the shingle tab back down, it should completely cover the nail.

The standing-seam copper roof at Domino's Farms office park in Ann Arbor, Michigan, is the largest in the USA and may very well be the largest in the world. The roof is 2,897 feet (more than a half-mile) long and 209 feet wide at its widest point. The structure houses the world headquarters of Domino's Pizza among others.

Biosphere 2 in the southern Arizona desert is a massive glass building as big as an airport hangar. Modeled after Earth, it was designed to be completely self-sustaining and capable of supporting human, animal and plant life. Copper tubing is used in the biosphere's extensive air handling and heat exchange systems because of its excellent heat transfer properties and reliability. Copper tubes filled with chilled water cool the air, while simultaneously absorbing the sun's radiant heat inside the dome. Copper is also used in the electrical wiring, as well as the motors and fans needed to distribute the cooler air.