Copper has earned a respected place in the related fields of architecture, building construction, and interior design.Kireta Jr., Andy (2009). The copper advantage, Metal Architecture, June 2009; www.metalarchitecture.com From cathedrals to castles and from homes to offices, copper is used for a variety of architectural elements, including roofs, flashings, gutters, downspouts, domes, spires, vaults, wall cladding, and building expansion joints.
The history of copper in architecture can be linked to its durability, corrosion resistance, prestigious appearance, and ability to form complex shapes.Austin, Jim (2006). Copper: The peacock of metals, Metal Roofing, April–May 2006; www.metalroofingmag.com For centuries, craftsmen and designers utilized these attributes to build aesthetically pleasing and long-lasting building systems.Seale, Wayne (2007). The role of copper, brass, and bronze in architecture and design; Metal Architecture, May 2007
For the past quarter century, copper has been designed into a much wider range of buildings, incorporating new styles, varieties of colors, and different shapes and textures.The Guide to Copper in Architecture; European Copper in Architecture Campaign; http://www.copperconcept.org/sites/default/files/attachment/2011/pubpdf145.pdf Copper clad walls are a modern design element in both indoor and outdoor environments.
Some of the world's most distinguished modern architects have relied on copper. Examples include Frank Lloyd Wright, who specified copper materials in all of his building projects; Michael Graves, an AIA Gold Medalist who designed over 350 buildings worldwide;Michael Graves & Associates Renzo Piano, who designed pre-patinated clad copper for the NEMO-Metropolis Museum of Science in Amsterdam;Metal Sight: The source for metal cladding in architecture; http://www.metalsight.com/projects/metropolis/ Malcolm Holzman, whose patinated copper shingles at the WCCO Television Communications Centre made the facility an architectural standout in Minneaoplis;; and Marianne Dahlbäck and Göran Månsson, who designed the Vasa Museum, a prominent feature of Stockholm's skyline, with copper cladding.Vasa Museet; http://www.vasamuseet.se/en/About/The-history-of-the-museum/ Architect Frank O. Gehry's enormous copper fish sculpture atop the Vila Olimpica in Barcelona is an example of the artistic use of copper.Fish sculpture at Vila Olimpica; Frank Gehry Architect; http://pastexhibitions.guggenheim.org/gehry/fish_sculpt_11.htmlMIMOA online architecture guide of Europe; http://www.mimoa.eu/projects/Spain/Barcelona/Fish Goto, Shihoko (2012). Copper in architecture, Business Insider, as published in Resource Investing News, March 14, 2012; http://www.businessinsider.com/copper-in-architecture-2012-3
Copper's most noteworthy aesthetic trait is its range of hues, from a bright metallic colour to iridescent brown to near black and, finally, to a greenish verdigris patina. Architects describe the array of browns as russet, chocolate, plum, mahogany, and ebony.The glory of copper; Metal Roofing Magazine, December 2002/January 2003 The metal's distinctive green patina has long been coveted by architects and designers.
This article describes practical and aesthetic benefits of copper in architecture as well as its use in exterior applications, interior design elements, and green buildings.
History
Copper has played a role in architecture for thousands of years. For example, in ancient Egypt, massive doors to the temple of Amen-Re at Karnak were clad with copper. In the 3rd Century B.C., copper roof shingles were installed atop of the Lowa Maha Paya Temple in Sri Lanka. And the Romans used copper as roof covering for the Pantheon in 27 B.C.Copper roofing in detail; Copper in Architecture; Copper Development Association, U.K., http://copperalliance.org.uk/resource-library/pub-156---copper-roofing-in-detail
Centuries later, copper and its alloys were integral in medieval architecture. The doors of the Church of the Nativity at Bethlehem (6th century) are covered with plates of bronze, cut out in patterns. Those of Hagia Sophia at Constantinople, of the 8th and 9th century, are wrought in bronze. Bronze doors on the Aachen Cathedral in Germany date back to about 800 A.D. Bronze baptistery doors at the Cathedral of Florence were completed in 1423 A.D. by Ghiberti.Architecture, European Copper Institute; http://copperalliance.eu/applications/architecture
The copper roof of Hildesheim Cathedral, installed in 1280 A.D., survives to this day.Copper Roofing in Detail; Copper in Architecture; Copper Development Association, U.K., Copper Roofing in Detail And the roof at Kronborg, one of northern Europe's most important Renaissance castles that was immortalized as Elsinore Castle in Shakespeare's Hamlet, was installed in 1585 A.D.Kronborg completed; Agency for Palaces and Cultural Properties, København, The copper on the tower was renovated in 2009.Agency for Palaces and Cultural Properties, Renovation of the Tower of Christianborg Palace., http://www.slke.dk/en/slotteoghaver/slotte/christiansborgslot/hovedslottet/renoveringaftaarnet.aspx?highlight=copper+roof
For years, copper was reserved mainly for public institutions, such as churches, government buildings, and universities. Copper roofs are often one of the most architecturally distinguishable features of these structures.
Today, architectural copper is used in roofing systems, flashings and copings, rain gutters and downspouts, building expansion joints, wall cladding, domes, spires, vaults, and various other design elements. Simultaneously, the metal has evolved from a weather barrier and exterior design element into indoor building environments where it is changing the way commercial and residential interiors are decorated.Copper's design potential highlights architectural seminars (2008). Building and Architectural News, Vol 62, No. 4., Reprint A4086 xx/08; Copper Development Association
In the 21st century, the use of copper continues to evolve in the indoor environment. Its recently proven antimicrobial properties reduce pathogenic bacterial loads on such products as handrails, bedrails, bathroom fixtures, counter tops, etc. These antimicrobial copper-based products are now being incorporated into public facilities (hospitals, nursing homes, mass transit facilities) as well as in residential buildings because of the public health benefits. (For main article, see: Antimicrobial copper-alloy touch surfaces.)
Benefits
Corrosion resistance As an architectural metal, copper provides excellent corrosion resistance.Preventing corrosion on copper roof systems, Professional Roofing, October 2004, www.professionalroofing.net Copper surfaces form tough oxide-sulfate patina coatings that protect underlying copper surfaces and resist corrosion for a very long time.
Copper corrodes at negligible rates in unpolluted air, water, de-aerated non-oxidizing acids, and when exposed to saline solutions, alkaline solutions, and organic chemicals. Copper roofing in rural atmospheres corrodes at rates of less than in 200 years.Corrosion of copper and copper alloys; Key to Metals: The world's most comprehensive metals database; http://www.keytometals.com/Article16.htm
Unlike most other metals, copper does not suffer from underside corrosion that can cause premature failures in roofing. With a copper roof, supporting substrates and structures usually fail long before the copper on the roof.
Architectural copper is, however, susceptible to corrosive attack under certain conditions. Oxidizing acids, oxidizing heavy-metal salts, alkalis, sulfur and nitrogen oxides, ammonia, and some sulfur and ammonium compounds can expedite copper corrosion. Precipitation in areas with a pH less than 5.5 may corrode copper, possibly before a patina or protective oxide film has the time to form. Acidic precipitation, known as acid rain, is due to emissions from fossil fuel combustion, chemical manufacturing, or other processes that release sulfur and nitrogen oxides into the atmosphere.Peters, Larry E. (2004). Preventing corrosion on copper roofing systems; Professional Roofing, October 2004, www.professionalroofing.net Erosion corrosion may occur when acidic water from a non-copper roof that does not neutralise the acidity, such as tile, slate, wood, or asphalt, falls on a small area of copper. Line corrosion can occur if the drip edge of an inert roofing material rests directly on copper. A solution to this may be to raise the lower edge of the shingles with a cant strip, or to provide a replaceable reinforcing strip between the shingles and the copper. Proper water-shedding design and detailing, which reduces the dwell time of acidic water on metal surfaces, can prevent the majority of atmospheric corrosion problems.
Brass, an alloy of copper and zinc, has good resistance to atmospheric corrosion, alkalis, and organic acids. In some potable waters and in seawater, however, brass alloys with 20% or more zinc may suffer corrosive attack.Houska, Catherine, 2002; Architectural metals have many capabilities, but also limitations, Snips; Nov 2002; 71, pgs. 12-24; www.snipsmag.com
Durability/long-life Copper roofs are extremely durable in most environments. They have performed well for over 700 years, primarily because of the protective patina that forms on copper surfaces. Tests conducted on 18th Century copper roofs in Europe showed that, in theory, they could last for one thousand years.
Low thermal movement Properly designed copper roofs minimize movements due to thermal changes. Copper's low thermal expansion, 40% less than zinc and lead, helps to prevent deterioration and failure. Also, copper's high melting point ensures that it will not creep or stretch as some other metals do.
On small gable roofs, thermal movement is relatively minor and usually is not an issue. On wide-span buildings over and when long panels are used, an allowance for thermal expansion may be necessary. This enables the roof to "float" over supporting substructures while remaining secure.Metal roofing basics: corrosion, strength and thermal movement are important issues to consider in specifying metal roofs; The Canadian Architect, Vol. 40, Issue 2 (Feb 1995), pp. 31-37
Low maintenance Copper does not require cleaning or maintenance. It is particularly suited for areas that are difficult or dangerous to access after installation.
Lightweight
When used as a fully supported roof covering, copper is half the weight (including substrate) of lead and only a quarter of tiled roofs. This generally provides savings in supporting structure and materials costs. Copper cladding offers additional opportunities to reduce the weight of copper structures (For more details, see: Copper cladding and Wall cladding).
Ventilation Copper does not require complex ventilation measures. It is suitable for both unventilated 'warm' and ventilated 'cold' roof constructions.
Radio frequency shielding
Sensitive electronic equipment are vulnerable to interference and unauthorized surveillance. These products also require protection from high voltages. Radio frequency (RF) shielding can address these issues by reducing the transmission of electric or magnetic fields from one space to another.
Copper is an excellent material for RF shielding because it absorbs radio and magnetic waves. Other useful properties for RF shielding is that copper has a high electrical conductivity, is ductile, malleable, and solders easily.Radio frequency shielding: Fundamentals; Copper Development Association; http://www.copper.org/applications/architecture/arch_dhb/fundamentals/radio_shielding.html