Copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

has earned a respected place in the related fields of

architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing building ...

building construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...

, and

interior design Interior design is the art and science of enhancing the interior of a building to achieve a healthier and more aesthetically pleasing environment for the people using the space. An interior designer is someone who plans, researches, coordi ...

.Kireta Jr., Andy (2009). The copper advantage, ''Metal Architecture,'' June 2009; www.metalarchitecture.com From

cathedral A cathedral is a church that contains the '' cathedra'' () of a bishop, thus serving as the central church of a diocese, conference, or episcopate. Churches with the function of "cathedral" are usually specific to those Christian denominatio ...

s to castles and from homes to

office An office is a space where an organization's employees perform administrative work in order to support and realize objects and goals of the organization. The word "office" may also denote a position within an organization with specific du ...

s, copper is used for a variety of architectural elements, including

roofs A roof ( : roofs or rooves) is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temper ...

, flashings, gutters,

downspout A downspout, waterspout, downpipe, drain spout, drainpipe, roof drain pipe,Francis Joseph Patry 1974. Roof Drain ArrangementUnited States Patent 3909412< or leader is a

domes,

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires a ...

s, vaults,

wall cladding Siding or wall cladding is the protective material attached to the exterior side of a wall of a house or other building. Along with the roof, it forms the first line of defense against the elements, most importantly sun, rain/snow, heat and cold ...

, and building

expansion joint An expansion joint, or movement joint, is an assembly designed to hold parts together while safely absorbing temperature-induced expansion and contraction of building materials, and vibration, or to allow movement due to ground settlement or seis ...

s. The history of copper in architecture can be linked to its durability,

corrosion resistance Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engin ...

, 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 Frank Lloyd Wright (June 8, 1867 – April 9, 1959) was an American architect, designer, writer, and educator. He designed more than 1,000 structures over a creative period of 70 years. Wright played a key role in the architectural movements o ...

, who specified copper materials in all of his building projects; Michael Graves, an AIA Gold Medalist who designed over 350 buildings worldwide;

Renzo Piano Renzo Piano (; born 14 September 1937) is an Italian architect. His notable buildings include the Centre Georges Pompidou in Paris (with Richard Rogers, 1977), The Shard in London (2012), the Whitney Museum of American Art in New York City ( ...

, who designed pre-patinated clad copper for the NEMO-Metropolis Museum of Science in

Amsterdam Amsterdam ( , , , lit. ''The Dam on the River Amstel'') is the capital and most populous city of the Netherlands, with The Hague being the seat of government. It has a population of 907,976 within the city proper, 1,558,755 in the urban ar ...

; 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 The Vasa Museum ( sv, Vasamuseet) is a maritime museum in Stockholm, Sweden. Located on the island of Djurgården, the museum displays the only almost fully intact 17th-century ship that has ever been salvaged, the 64-gun warship '' Vasa'' that sa ...

, a prominent feature of Stockholm's skyline, with copper cladding. Architect

Frank O. Gehry Frank Owen Gehry, , FAIA (; ; born ) is a Canadian-born American architect and designer. A number of his buildings, including his private residence in Santa Monica, California, have become world-renowned attractions. His works are considered ...

's enormous copper fish sculpture atop the Vila Olimpica in

Barcelona Barcelona ( , , ) is a city on the coast of northeastern Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second most populous municipality of Spain. With a population of 1.6 million within ci ...

is an example of the artistic use of copper. Copper's most noteworthy aesthetic trait is its range of

hue In color theory, hue is one of the main properties (called color appearance parameters) of a color, defined technically in the CIECAM02 model as "the degree to which a stimulus can be described as similar to or different from stimuli that ...

s, from a bright metallic colour to iridescent brown to near black and, finally, to a greenish

verdigris Verdigris is the common name for blue-green, copper-based pigments that form a patina on copper, bronze, and brass. The technical literature is ambiguous as to its chemical composition. Some sources refer to "neutral verdigris" as copper(II) ...

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 Amun (; also ''Amon'', ''Ammon'', ''Amen''; egy, jmn, reconstructed as (Old Egyptian and early Middle Egyptian) → (later Middle Egyptian) → (Late Egyptian), cop, Ⲁⲙⲟⲩⲛ, Amoun) romanized: ʾmn) was a major ancient Egyptian ...

Karnak The Karnak Temple Complex, commonly known as Karnak (, which was originally derived from ar, خورنق ''Khurnaq'' "fortified village"), comprises a vast mix of decayed temples, pylons, chapels, and other buildings near Luxor, Egypt. Constr ...

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 Roman or Romans most often refers to: *Rome, the capital city of Italy * Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a lette ...

used copper as roof covering for the

Pantheon Pantheon may refer to: * Pantheon (religion), a set of gods belonging to a particular religion or tradition, and a temple or sacred building Arts and entertainment Comics *Pantheon (Marvel Comics), a fictional organization * ''Pantheon'' (Lone S ...

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 In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...

architecture. The doors of the

Church of the Nativity The Church of the Nativity, or Basilica of the Nativity,; ar, كَنِيسَةُ ٱلْمَهْد; el, Βασιλική της Γεννήσεως; hy, Սուրբ Ծննդեան տաճար; la, Basilica Nativitatis is a basilica located in B ...

Bethlehem Bethlehem (; ar, بيت لحم ; he, בֵּית לֶחֶם '' '') is a city in the central West Bank, Palestine, about south of Jerusalem. Its population is approximately 25,000,Amara, 1999p. 18.Brynen, 2000p. 202. and it is the capital o ...

(6th century) are covered with plates of bronze, cut out in patterns. Those of

Hagia Sophia Hagia Sophia ( 'Holy Wisdom'; ; ; ), officially the Hagia Sophia Grand Mosque ( tr, Ayasofya-i Kebir Cami-i Şerifi), is a mosque and major cultural and historical site in Istanbul, Turkey. The cathedral was originally built as a Greek Ortho ...

Constantinople la, Constantinopolis ota, قسطنطينيه , alternate_name = Byzantion (earlier Greek name), Nova Roma ("New Rome"), Miklagard/Miklagarth (Old Norse), Tsargrad ( Slavic), Qustantiniya ( Arabic), Basileuousa ("Queen of Cities"), Megalopolis ( ...

, 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 Florence Cathedral, formally the (; in English Cathedral of Saint Mary of the Flower), is the cathedral of Florence, Italy ( it, Duomo di Firenze). It was begun in 1296 in the Gothic style to a design of Arnolfo di Cambio and was structurally ...

were completed in 1423 A.D. by

Ghiberti Lorenzo Ghiberti (, , ; 1378 – 1 December 1455), born Lorenzo di Bartolo, was an Italian Renaissance sculptor from Florence, a key figure in the Early Renaissance, best known as the creator of two sets of bronze doors of the Florence Baptistery ...

. The copper roof of

Hildesheim Cathedral Hildesheim Cathedral (German: '), officially the Cathedral of the Assumption of Mary (German: ''Hohe Domkirche St. Mariä Himmelfahrt'') or simply St. Mary's Cathedral (German: ''Mariendom''), is a medieval Roman Catholic cathedral in the city cent ...

, 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
/ref> And the roof at

Kronborg Kronborg is a castle and stronghold in the town of Helsingør, Denmark. Immortalized as Elsinore in William Shakespeare's play ''Hamlet'', Kronborg is one of the most important Renaissance castles in Northern Europe and was inscribed on the UNE ...

, one of northern Europe's most important

Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history The history of Europe is traditionally divided into four time periods: prehistoric Europe (prior to about 800 BC), classical antiquity (800 BC to AD ...

castles that was immortalized as

Elsinore Castle Kronborg is a castle and stronghold in the town of Helsingør, Denmark. Immortalized as Elsinore in William Shakespeare's play ''Hamlet'', Kronborg is one of the most important Renaissance castles in Northern Europe and was inscribed on the UNE ...

Shakespeare William Shakespeare ( 26 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's natio ...

's ''

Hamlet ''The Tragedy of Hamlet, Prince of Denmark'', often shortened to ''Hamlet'' (), is a tragedy written by William Shakespeare sometime between 1599 and 1601. It is Shakespeare's longest play, with 29,551 words. Set in Denmark, the play depicts ...

'', was installed in 1585 A.D. The copper on the tower was renovated in 2009. 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 gutter A rain gutter, eavestrough, eaves-shoot or surface water collection channel is a component of a water discharge system for a building. It is necessary to prevent water dripping or flowing off roofs in an uncontrolled manner for several reasons ...

s and

downspout A downspout, waterspout, downpipe, drain spout, drainpipe, roof drain pipe,Francis Joseph Patry 1974. Roof Drain ArrangementUnited States Patent 3909412< or leader is a

, domes,

s, 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. In the 21st century, the use of copper continues to evolve in the indoor environment. Its recently proven antimicrobial properties reduce pathogenic

bacterial Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...

loads on such products as

handrail A handrail is a rail that is designed to be grasped by the hand so as to provide safety or support. In Britain, handrails are referred to as banisters. Handrails are usually used to provide support for body or to hold clothings in a bathroom o ...

s, bedrails, bathroom fixtures, counter tops, etc. These antimicrobial copper-based products are now being incorporated into public facilities ( hospitals,

nursing home A nursing home is a facility for the residential care of elderly or disabled people. Nursing homes may also be referred to as skilled nursing facility (SNF) or long-term care facilities. Often, these terms have slightly different meanings to i ...

s, mass transit facilities) as well as in residential buildings because of the public health benefits. ''(For main article, see:

Antimicrobial copper-alloy touch surfaces Antimicrobial copper-alloy touch surfaces can prevent frequently touched surfaces from serving as reservoirs for the spread of pathogenic microbes. This is especially true in healthcare facilities, where harmful viruses, bacteria, and fungi coloni ...

.)''

Benefits

Corrosion resistance

As an architectural metal, copper provides excellent

.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 chemical In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

s. Copper roofing in rural atmospheres corrodes at rates of less than in 200 years. 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 Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

, 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. Chickenvane

Brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wit ...

, 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 Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

may suffer corrosive attack. Kresge Auditorium, MIT (roof detail)

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 Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions. Temperature is a monotonic function of the average molecular kinetic ...

, 40% less than zinc and lead, helps to prevent deterioration and failure. Also, copper's high

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depen ...

ensures that it will not creep or stretch as some other metals do. D-NW-Bad Salzuflen - Leopoldsprudel

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.

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 There are four main techniques used today in the UK and mainland Europe for copper cladding a building: * seamed-cladding (typically 0.7mm thick copper sheet on the facade): max 600mm by 4000mm 'seam centres'. * shingle-cladding (typically ma ...

and

Wall cladding Siding or wall cladding is the protective material attached to the exterior side of a wall of a house or other building. Along with the roof, it forms the first line of defense against the elements, most importantly sun, rain/snow, heat and cold ...

).''

Ventilation

Copper does not require complex

ventilation Ventilation may refer to: * Ventilation (physiology), the movement of air between the environment and the lungs via inhalation and exhalation ** Mechanical ventilation, in medicine, using artificial methods to assist breathing *** Ventilator, a m ...

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 voltage High voltage electricity refers to electrical potential large enough to cause injury or damage. In certain industries, ''high voltage'' refers to voltage above a certain threshold. Equipment and conductors that carry high voltage warrant sp ...

s. Radio frequency (RF) shielding can address these issues by reducing the transmission of

electric Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...

or magnetic fields from one space to another. Copper is an excellent material for RF shielding because it absorbs

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmi ...

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 RF shielding enclosures filter a range of frequencies for specific conditions. Properly designed and constructed copper enclosures satisfy most RF shielding needs, from computer and electrical switching rooms to hospital CAT-scan and

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...

facilities. Special attention needs to be addressed regarding potential shield penetrations, such as doors, vents, and cables. A shield can be effective against one type of electromagnetic field but not against another. For example, a copper foil or screen RF shield will be minimally effective against power frequency magnetic fields. A power frequency magnetic shield could offer little reduction of radio frequency fields. The same is true for different RF frequencies. A simple large-mesh screen shield can work well for lower frequencies, but can be ineffective for microwaves. Bradbury Buildings, Belfast (1) - geograph

Bradbury Buildings, Belfast (1) - geograph

Sheet copper for RF shielding can be formed into essentially any shape and size. Electrical connection to a grounding system provides an effective RF enclosure.

Lightning protection

Lightning strike A lightning strike or lightning bolt is an electric discharge between the atmosphere and the ground. Most originate in a cumulonimbus cloud and terminate on the ground, called cloud-to-ground (CG) lightning. A less common type of strike, ground- ...

protection minimizes damage to buildings during lightning terminations. This is usually accomplished by providing multiple interconnected pathways of low electrical impedance to the ground. Copper and its alloys are the most common materials used in residential lightning protections, however in industrial, chemically corrosive environments, the copper may need to be clad in tin.Copper lightning protection systems save lives, billions; Building and Architectural News, #80, Winter 1995; Copper effectively facilitates the transmission of lightning energy to the ground because of its excellent electrical conductivity. Also, it bends easily compared to other conductor materials. When copper roofing, gutters, and rain leaders are electrically bonded to an earth termination facility, a pathway of low electrical impedance to ground is provided, however without dedicated conduction pathways to concentrate the discharge channel, a disperse energized surface may not be the most desirable.Lightning protection; in Copper in Architecture Design Handbook; Copper Development Association Inc., http://www.copper.org/applications/architecture/arch_dhb/fundamentals/lightning.html Because copper has a higher electrical conductivity than aluminium and its impedance during a lightning termination is less, copper allows for the use of less cross-sectional surface area per linear length, in its woven wires pathway than does aluminum. Also, aluminium cannot be used in poured concrete or for any component underground due to its galvanic properties. To be effective, lightning protection systems generally maximize the surface area contact between the conductors and the earth through a ground grid of varying designs. To supplement grounding grids in low-conductivity earth, such as sand or rock, long, hollow copper tubes filled with metallic salts are available. These salts leach through holes in the tube, making the surrounding soil more conductive as well as increasing the overall surface area which decreases effective resistance. Copper roofs may be used as part of a lightning protection scheme where the copper

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...

, gutters and rainwater pipes can be linked and bonded to an earth termination facility. The thickness of copper specified for roofing materials is usually adequate for lightning protection. A dedicated lightning protection system may be recommended to adequate lightning protection with an installed copper roof system. The system would include air terminals and intercepting conductors on the roof, a system of ground electrodes, and a system of down-conductors connecting the roof and ground components. It is recommended that the copper roof be bonded to the system of conductors. Bonding ensures that the conductors and roof remain at equipotential and reduce side flashing and possible roof damage.

Wide range of finishes

It is sometimes desirable to chemically alter the surface of copper or copper alloys to create a different color. The most common colors produced are brown or statuary finishes for

brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wit ...

or bronze and green or patina finishes for

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

.How to apply statuary and patina finishes, Application Data Sheet for Copper, Brass and Bronze, Copper Development Association Inc. Mechanical surface treatments, chemical coloring, and coatings are described elsewhere in this article at: '' Finishes.''

Design continuity

Architects often look to architectural copper for continuity in design elements. For example, a copper roofing system may be designed with copper flashings, weatherings, vents, gutters, and downpipes. Cover details may include cornices, moldings, finials and

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable ...

s. With the growing use of vertical cladding, vertical and roofing surfaces can run into each other so that complete continuity of material and performance is maintained.

Rain screen A rainscreen is an exterior wall detail where the siding (wall cladding) stands off from the moisture- resistant surface of an air/water barrier applied to the sheathing to create a capillary break and to allow drainage and evaporation. The ''ra ...

s and curtain walling (often linked with transoms and

mullion A mullion is a vertical element that forms a division between units of a window or screen, or is used decoratively. It is also often used as a division between double doors. When dividing adjacent window units its primary purpose is a rigid supp ...

s) are also gaining popularity in modern architectural design.The guide to copper in architecture; European Copper in Architecture Campaign; http://www.copperconcept.org/sites/default/files/attachment/2011/pubpdf145.pdf

Antimicrobial

Extensive worldwide tests have proved that uncoated copper and copper alloys (e.g., brass, bronze, copper nickel, copper-nickel-zinc) have strong intrinsic antimicrobial properties with efficacies against a wide range of disease-resistant

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

and

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...

es. After years of testing, the U.S. approved the registration of over 300 different copper alloys (copper, brasses, bronzes, copper-nickels, and nickel-silvers) as antimicrobial materials. These developments are creating markets for antimicrobial copper and copper alloys in interior architecture. To meet the design needs for building surfaces, structures, fixtures, and components, antimicrobial copper-based products are available in a wide range of colors, finishes, and mechanical properties.Antimicrobial Copper, www.antimicrobialcopper.com Copper handrails, counter tops, hallways, doors, push plates, kitchens, and bathrooms are just some of the antimicrobial products approved for hospitals, airports, offices, schools, and army barracks to kill harmful bacteria. See: a list of products approved in the U.S.

Sustainability

While a universally accepted definition of sustainability remains elusive, the

Brundtland Commission The Brundtland Commission, formerly the World Commission on Environment and Development, was a sub-organization of the United Nations (UN) that aimed to unite countries in pursuit of sustainable development. It was founded in 1983 when Javier Pé ...

of the

United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoniz ...

defined sustainable development as development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Sustainability, the long-term maintenance of responsibility, requires the reconciliation of environmental, social equity and economic demands. These "three pillars" of sustainability encompass the responsible management of resource use. Also, it can mean that we can use a resource which won't cease to be abundant despite increasing intake. Copper is a sustainable material. Its durability offers long service with little maintenance. Its high electrical and thermal energy efficiencies reduce the waste of electrical energy. Its antimicrobial properties destroy pathogenic microorganisms that cause disease. And its high scrap value and ability to be continuously recycled without any loss in performance ensure its responsible management as a valuable resource.

Life cycle inventory Life cycle assessment or LCA (also known as life cycle analysis) is a methodology for assessing environmental impacts associated with all the stages of the life cycle of a commercial product, process, or service. For instance, in the case of ...

(LCI) information on copper tube, sheet, and wire products, using

ISO standards The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in A ...

and covering the mining and primary copper production sectors (i.e., smelting and refining) is available. Used in life cycle assessments (LCAs), particularly in the building and construction sector, LCI datasets assist manufacturers of copper-containing products with compliance and voluntary improvement initiatives. They also support policy makers in the development of environmental guidelines and regulations with the aim of fostering sustainable development. The long lifetime of copper roofing and cladding has a significant positive effect on whole life assessments of copper versus other materials in terms of

embodied energy Embodied energy is the sum of all the energy required to produce any goods or services, considered as if that energy was incorporated or 'embodied' in the product itself. The concept can be useful in determining the effectiveness of energy-produ ...

consumption (i.e., the total energy consumed during every phase of each lifecycle in MJ/m²), CO₂ generation, and cost.

Recyclability

Recyclability is a key factor of a sustainable material. It reduces the need to mine new

resources Resource refers to all the materials available in our environment which are technologically accessible, economically feasible and culturally sustainable and help us to satisfy our needs and wants. Resources can broadly be classified upon their av ...

and requires less energy than

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic ...

. Copper and its alloys are virtually 100%

recyclable Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...

and can be recycled infinitely without any loss of quality (i.e., copper does not degrade (i.e.,

downcycle Downcycling, or cascading, is the recycling of waste where the recycled material is of lower quality and functionality than the original material. Often, this is due to the accumulation of tramp elements in secondary metals, which may exclude t ...

) after each recycling loop as do most non-metallic materials, if they are recyclable at all). Copper retains much of its primary metal value: premium-grade scrap normally contains at least 95% of the value of primary metal from newly mined

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...

. Scrap values for competing materials range from about 60% down to 0%. And copper recycling requires only around 20% of the energy needed to extract and process primary metal. Currently, around 40% of Europe's annual copper demand and about 55% of copper used in architecture come from recycled sources. New copper coil and sheet often have 75%-100% recycled content. By 1985, more copper was recycled than the total amount of copper that was consumed in 1950. This is due to the relative ease of reusing processing waste and salvaging copper from products after their useful life. Copper-cupola

Cost effectiveness

Performance, maintenance, service life, and recovery costs from recycling are factors that determine the cost effectiveness of building components. While copper's initial cost is higher than some other architectural metals, it usually does not need to be replaced during the life of a building. Due to its durability, low maintenance, and ultimate

salvage value ''Residual value'' is one of the constituents of a leasing calculus or operation. It describes the future value of a good in terms of absolute value in monetary terms and it is sometimes abbreviated into a percentage of the initial price when the i ...

, the additional cost for copper may be insignificant over the life of a roofing system. Copper roofing is considerably less expensive than

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

, slate, or hand-made

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

tiles. Its costs are comparable with

, stainless steel,

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

and even some clay and

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

tiles when considering overall roofing costs (including structure). Some studies indicate that copper is a more cost-effective material on a life cycle basis than other roof materials with a lifetime of 30 years or more. A European study comparing roofing costs of copper with other metals, concrete and clay tiles, slate, and bitumen found that in the medium to long-term (for lives of 60 to 80 years and 100 years and over), copper and stainless steel were the most cost effective roofing materials of all materials examined. Installation techniques such as prefabrication, in-situ machine forming, mechanized seaming, and the long-strip system help to reduce the installation costs of copper roofing. By lowering installation costs, these techniques permit designers to specify copper into a wider array of building types, not just large prestigious projects as had been common in the past. Since scrap copper retains much of its primary value, copper's life cycle costs are reduced when accounting for its salvage value. For more information, see

Recyclability Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...

section in this article.

Pure vs. alloyed copper

Pure copper. Unlike other metals, copper is frequently used in its pure (99.9% Cu) unalloyed form for sheet and strip applications in roofing, exterior cladding, and flashing. Tempering is a heat treatment technique used to increase the toughness of metals. Tempers determine the

ductility Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile str ...

of the metal, and therefore how well it forms and will hold its shape without additional support. In the U.S., copper is available in six tempers: 060 soft, hard cold rolled, cold rolled high yield, half hard, three quarter hard, and hard. In the U.K., only three designations exist: soft, half-hard, and hard. Copper and its alloys are defined in the U.S. in Standard Designations for Copper and Copper Alloys by ASTM; in Europe by BS EN 1172: 1997 - 'Copper and Copper Alloys in Europe'; and in the U.K. by the British Standard Code of Practice CP143: Part12: 1970. Cold rolled copper temper is by far the most popular in building construction in the U.S. It is less malleable than soft copper but is far stronger. Cold rolled hard tempered copper is often recommended for roofing and flashing installations. Roof sheets with higher tempers may be specified for certain applications. Soft tempered copper is extremely malleable and offers far less resistance than cold rolled copper to the stresses induced by expansion and contraction. It is used for intricate ornamental work and where extreme forming is required, such as in complicated thru-wall flashing conditions. The major use for high-yield copper is in flashing products, where malleability and strength are both important. The thickness of sheet and strip copper is measured in the U.S. by its weight in ounces per square foot. Thicknesses commonly used in construction in the U.S. are between and . Since the industry often uses gauge numbers or actual thicknesses for sheet metal or other building materials, it is necessary to convert between the different measurement systems. In Europe, phosphorus de-oxidized non-arsenical copper is used with the designation C106. The copper is rolled to thicknesses ranging between ( for curtain walling) but a thickness is usually used for roofing. Alloyed copper. Copper alloys, such as brass and bronze, are also used in residential and commercial building structures. Variations in color stem primarily from differences in the alloy chemical composition. Some of the more popular copper alloys and their associated Unified Numbering System (UNS) numbers developed by ASTM and SAE are as follows: Cu-alloy-colours

In practice, the term 'bronze' may be used for a variety of copper alloys with little or no tin if they resemble true bronzes in color. Further information on architectural copper alloys is available.

Selection criteria

The criteria by which copper and copper alloys are selected for architectural projects include color, strength, hardness, resistance to fatigue and corrosion, electrical and thermal conductivity, and ease of fabrication. Appropriate thicknesses and tempers for specific applications are essential; substitutions can lead to inadequate performance. Architectural copper is generally used in sheet and strip. Strip is or less in width, while sheet is over in width, up to in width by in length, plus in coil form.

Structural considerations

Structural considerations play an important role in the proper design of copper applications. The primary concern is about thermal effects: movement and stresses related to temperature variations. Thermal effects can be accommodated by preventing movement and resisting cumulative stresses or by allowing movement at predetermined locations, thereby relieving anticipated thermal stresses. Statue of Liberty frontal 2

Wind resistance In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding flu ...

is an important structural consideration.

Underwriters Laboratories The UL enterprise is a global safety science company headquartered in Northbrook, Illinois, composed of three organizations, UL Research Institutes, UL Standards & Engagement and UL Solutions. Established in 1894, the UL enterprise was founded as ...

(UL) conducted a series of tests on copper roof systems. A copper standing-seam roof with test panels was subjected to the UL 580, Uplift Resistance Test Protocol. The copper system did not exhibit unusual deformation, the cleats did not loosen from the structural deck, and the system passed UL 580 requirements. UL-90 designation was granted.Sternthal, Daniel (2002). Long-pan expansion, wind uplift, and line corrosion; ''Metal Roofing Magazine,'' December 2002/January 2003Sternthal, Daniel (1998). A primer on copper roofing, ''The Construction Specifier,'' Magazine of the Construction Specifications Institute, September 1998

Joining

Copper and its alloys are readily joined by mechanical techniques, such as crimping, staking, riveting, and bolting; or by bonding techniques, such as

solder Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable ...

ing,

brazing Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal. Brazing differs from we ...

and

welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as bra ...

. Selection of the best joining technique is determined by service requirements, joint configuration, thickness of components, and alloy composition. Soldering is the preferred joining method where strong, watertight joints are required, such as for internal gutters, roofing, and flashing applications. A soldered seam joins two pieces of copper into a cohesive unit that expands and contracts as one piece. Well-soldered seams are often stronger than the original base material and provide many years of service. Mechanical fasteners, such as screws, bolts, and rivets, are often used to strengthen the joints and seams. Continuous, long runs of soldered seams can cause stress fractures and should therefore be avoided.Architectural considerations, Copper in Architecture Design Handbook, Copper Development Association Inc., http://www.copper.org/applications/architecture/arch_dhb/fundamentals/arch_considerations.html Common 50-50 tin-lead bar solder is often used for uncoated copper; 60-40 tin-lead solder is used for lead-coated copper.Sternthal, Daniel (2000). Copper flashings in contemporary construction, ''The Construction Specifier,'' Magazine of the Construction Specifications Institute, October 2000 Many lead-free solders are also acceptable. Adhesives can be used in certain applications. Relatively thin sheet alloys can be bonded to plywood or certain types of foam which act as rigid insulation. Brazing is the preferred method for joining pipe and tube copper alloys. Copper metal sections are joined with a non-ferrous filler material with a melting point above 800 degrees Fahrenheit but below the melting point of the base metals. Blind or concealed joints are recommended since the color match of silver filler material is fair to poor. Welding is a process where pieces of copper are effectively melted together, either by flame, electricity, or high pressure. With increasing availability of modern TIG welding equipment, welding of even light-gauge copper decorative elements is gaining acceptance. Instructional videos are available regarding fluxing and

ing techniques; how to make flat seam solder joints, double-lock standing seams, lap seams, soldering vertical sheet copper lap seams, and stitches (including the butterfly stitch); as well as copper

tinning Tinning is the process of thinly coating sheets of wrought iron or steel with tin, and the resulting product is known as tinplate. The term is also widely used for the different process of coating a metal with solder before soldering. It is m ...

bending In applied mechanics, bending (also known as flexure) characterizes the behavior of a slender structural element subjected to an external load applied perpendicularly to a longitudinal axis of the element. The structural element is assumed to ...

, flaring, and

Sealants

Sealants are an alternative to solder where additional strength is not required. In most cases, sealants should not be necessary with a properly designed copper installation. They are at best a relatively short-term solution requiring frequent maintenance. Regardless, sealant-filled joints have been used successfully as a secondary waterproofing measure for standing seam and batten seam roofing applications where low-sloped roofs are less than . Sealants can also be used in joints that are primarily designed to accommodate thermal movement of the copper. The sealants used should be tested by the manufacturer and designated as compatible for use with copper. In general,

butyl In organic chemistry, butyl is a four- carbon alkyl radical or substituent group with general chemical formula , derived from either of the two isomers (''n''-butane and isobutane) of butane. The isomer ''n''-butane can connect in two ways, gi ...

polysulfide Polysulfides are a class of chemical compounds containing chains of sulfur atoms. There are two main classes of polysulfides: inorganic and organic. Among the inorganic polysulfides, there are ones which contain anions, which have the general formu ...

polyurethane Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from ...

, and other inorganic or

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, an ...

-based sealants are reasonably compatible with copper.

Acrylic Acrylic may refer to: Chemicals and materials * Acrylic acid, the simplest acrylic compound * Acrylate polymer, a group of polymers (plastics) noted for transparency and elasticity * Acrylic resin, a group of related thermoplastic or thermosett ...

, neoprene, and nitrile-based sealants actively corrode copper. Silicone sealants are somewhat successful with copper but their suitability should be verified before application.

Galvanic corrosion

Galvanic corrosion is an

electrochemical Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outc ...

process whereby one metal

corrode Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engin ...

s preferentially to another when both metals are in electrical contact with each other in the presence of an electrolyte, such as moisture and salts. This is because the dissimilar metals have different

electrode potential In electrochemistry, electrode potential is the electromotive force of a galvanic cell built from a standard reference electrode and another electrode to be characterized. By convention, the reference electrode is the standard hydrogen electrode ( ...

s. The potential difference between the dissimilar metals is the driving force for the accelerated attack on the metal with the lower galvanic number (i.e., the anode). Over time, the anode metal dissolves into the electrolyte.Flashings and copings, Copper in Architecture Design Handbook, Copper Development Association Inc., http://www.copper.org/applications/architecture/arch_dhb/flashings_copings/intro.html Metals are ranked according to galvanic numbers as a qualitative measure of their nobility. These numbers qualify the resistance to corrosion of any metal when in contact with other metals. A larger difference in the galvanic number between two metals in contact with each other indicates a greater potential for corrosion. The galvanic numbers of the most common metals used in construction are ranked as follows: 1. aluminum; 2. zinc; 3. steel; 4. iron; 5. stainless steel - active; 6. tin; 7. lead; 8. copper; 9. stainless steel - passive. Galvanic corrosion is a primary concern with metal roof maintenance. Marine environments present an additional concern due to the higher concentration of salts in the air and water. Copper is one of the most noble metals. It will not be harmed by contact with other metals but it will cause corrosion to some other metals if contacted directly. The principal metals of concern regarding direct contact with copper are aluminum, light-gauge steel, and zinc. Aluminum and steel flashings and galvanized steel fasteners should not be used with copper. Runoff from a copper roof corrodes aluminum and steel guttering. It is not necessary to isolate copper from lead, tin or many stainless steels under most circumstances.Architectural Considerations, Copper in Architecture Design Handbook, Copper Development Association Inc., http://www.copper.org/applications/architecture/arch_dhb/fundamentals/arch_considerations.html When it is not possible to avoid contact, an effective method of material separation is required. If paints or coatings are used for isolation, they should be compatible with both metals.

Bituminous Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term ...

zinc chromate Zinc chromate, Zn Cr O4, is a chemical compound containing the chromate anion, appearing as odorless yellow powder or yellow-green crystals, but, when used for coatings, pigments are often added. It is used industrially in chromate conversion c ...

primers can be used between copper and aluminum. Bituminous, zinc chromate, or a red lead primer can be effective in separating copper from iron and other ferrous metals. Taping or gasketing with non-absorptive materials or sealants are effective in separating copper from all other metals. In areas with severe exposure, lead or similar gasketing materials should be used, except between copper and aluminum. Water draining from copper surfaces should be prevented from exposure to aluminum and galvanized steel as traces of copper salts may accelerate corrosion. In some cases, anodizing may protect thicker aluminum, such as aluminum window system mullions.

Natural patinas

Copper goes through a natural

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

process that forms a unique protective patina on the metal. The surface of the metal undergoes a series of color changes: from iridescent/salmon pinks to oranges and reds interspersed with brassy yellows, blues, greens and purples. As the oxide thickens, these colors are replaced by russet and chocolate browns, dull slate grays or blacks, and finally to a light-green or blue-green. Copper's patination process is complex. It starts immediately on exposure to the environment with the initial formation of

copper oxide Copper oxide is a compound from the two elements copper and oxygen. Copper oxide may refer to: * Copper(I) oxide (cuprous oxide, Cu2O) * Copper(II) oxide Copper(II) oxide or cupric oxide is an inorganic compound with the formula CuO. A black so ...

conversion films that are noticeable within six months. Weathering may be uneven at first but the film becomes even after about nine months. Within the first few years, cuprous and cupric sulfide conversion films darken the surface to browns and then dull slate gray or dull black. Continued weathering transforms the sulfide films to

sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...

s, which are the notable blue-green or gray-green patinas. Dachfläche Stadthalle Heidelberg

The rate of patination conversion is dependent upon copper's exposure to moisture, salt, and acidity from acid-forming pollutants. In marine climates, the entire patination process can take seven to nine years. In industrial environments, patina formation reaches its final stage in about fifteen to twenty-five years. In clean rural atmospheres with low concentrations of airborne sulfur dioxide, the final stage may take ten to thirty years to develop. In arid environments, a patina may not form at all if the moisture is insufficient. Where patination does take place in arid environments, it may mature to an ebony or nut brown. In all environments except the coastal areas, patination takes longer for vertical surfaces due to more rapid water runoff. The copper patinas are very thin: just in thickness. Yet, they are highly adherent to the underlying copper metal. The initial and intermediate oxide and sulfide patina films are not particularly corrosion resistant. The final sulfate patina is a particularly durable layer that is highly resistant to all forms of atmospheric corrosion and protects the underlying metal against further weathering. As patination progresses and the durable sulfate layer forms, the rate of corrosion decreases, averaging between per year. For a sheet, this equates to less than 5% corrosion over a period of 100 years. Further information is available on copper patination.

Finishes

Copper and its alloys can be 'finished' to embark a particular look, feel, and/or color. Finishes include mechanical surface treatments, chemical coloring, and coatings. These are described here. Mechanical surface treatments. Several types of mechanical surface treatments exist. Mill finishes are derived by normal production processes, such as rolling, extrusion, or casting. "Buffeted" finishes impart bright mirror-like appearances after grinding, polishing, and buffing. "Directional textured" finishes provide a smooth, velvety satin sheen in a continuous pattern of fine nearly parallel scratches. "Non-directional textured matte" finishes achieve a rough texture, primarily on castings, as spray sand or metal shot are applied under high pressure. And "patterned" finishes, made by pressing a copper alloy sheet between two rolls, produce a textured and embossed look. Chemically induced patina. Architects sometimes request a particular patina color at installation. Factory-applied chemically induced pre-patination systems can produce a wide range of colored finishes similar to natural patination. Pre-patinated copper is particularly useful in repairs when there is need to provide close color matches to old copper roofs. Pre-patination is also considered in some modern building materials, such as vertical cladding, soffits, and gutters where patination is desired but would not ordinarily occur. Chemical coloring of metals is an art involving craftsmanship and experience. Coloring techniques depend upon time, temperature, surface preparation, humidity and other variables. Pre-patinated copper sheets are produced by fabricators under controlled environments using patented chemical processes. Green patina finishes are primarily developed using acid chloride or acid sulfate. Treatments with ammonium chloride (

sal ammoniac Salammoniac, also sal ammoniac or salmiac, is a rare naturally occurring mineral composed of ammonium chloride, NH4Cl. It forms colorless, white, or yellow-brown crystals in the isometric-hexoctahedral class. It has very poor cleavage and is ...

), cuprous chloride/

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

, and

ammonium sulfate Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen a ...

are somewhat successful.Copper Brass Bronze Design Handbook: Architectural Applications, Copper Development Association, 1994 Statuary finishes can be produced in light, medium, and dark brown, depending on the concentration and number of coloring applications. One advantage is that the treatment disguises surface markings on bright mill finish copper and can advance the natural patination process. Because of the number of variables involved, chemically induced patinas are prone to problems such as a lack of adhesion, excessive staining of adjacent materials, and inability to achieve reasonable color uniformity over large surface areas. Chemical patination applied in the field is not recommended due to variations in temperature, humidity, and chemical requirements. Warranties are prudent when purchasing pre-patinated copper for architectural projects. Useful techniques and recipes for coloring copper, brass, yellow-brass, bronze, cast bronze, gilding metal, along with various physical and chemical textural finishes are available. Coatings. Clear coatings preserve the natural color, warmth and metallic tone of copper alloys. However, particularly on exterior applications, they introduce maintenance into what is naturally a maintenance-free material. They are organic chemicals that are dry at ambient temperatures or require heat for curing or solvent evaporation. Examples of clear organic coatings include

alkyd An alkyd is a polyester resin modified by the addition of fatty acids and other components. Alkyds are derived from polyols and organic acids including dicarboxylic acids or carboxylic acid anhydride and triglyceride oils. The term ''alkyd'' is a m ...

acrylic Acrylic may refer to: Chemicals and materials * Acrylic acid, the simplest acrylic compound * Acrylate polymer, a group of polymers (plastics) noted for transparency and elasticity * Acrylic resin, a group of related thermoplastic or thermosett ...

, cellulose acetate butyrate, epoxy,

nitrocellulose Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...

, silicone, and urethane. Further details are available. Oils and waxes exclude moisture from copper surfaces and simultaneously enhance their appearance by bringing out a rich luster and depth of color. Oiling is typically used to prolong the time exposed copper remains in a brown to black tone. It will not keep copper shiny on an exterior installation. Oils and waxes offer short-term protection for exterior applications and longer-term protection for interior applications. Oiling predominates for roofing and flashing work. The most popular oils are Lemon Oil, U.S.P., Lemon Grass Oil, Native E.I., paraffin oils, linseed oil, and

castor oil Castor oil is a vegetable oil pressed from castor beans. It is a colourless or pale yellow liquid with a distinct taste and odor. Its boiling point is and its density is 0.961 g/cm3. It includes a mixture of triglycerides in which about ...

. On copper roofing or flashing, reapplication as infrequently as once every three years can effectively retard patina formation. In arid climates, the maximum span between oilings may be extended to from three to five years. Waxing is generally reserved for architectural components subject to close inspection and/or traffic. Mixes considered satisfactory include

Carnauba wax Carnauba (; pt, carnaúba ), also called Brazil wax and palm wax, is a wax of the leaves of the carnauba palm ''Copernicia prunifera'' (synonym: ''Copernicia cerifera''), a plant native to and grown only in the northeastern Brazilian states of ...

and wood turpentine, or

beeswax Beeswax (''cera alba'') is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in or at the hive. The hive work ...

and wood turpentine, or paste waxes. Opaque paint coatings are used primarily for work applied over copper when substrate integrity and longevity are desired but a specific color other than the naturally occurring copper hues is required. Zinc-tin coatings are an alternative to lead coatings since they have approximately the same appearance and workability.

Vitreous enamel Vitreous enamel, also called porcelain enamel, is a material made by fusing powdered glass to a substrate by firing, usually between . The powder melts, flows, and then hardens to a smooth, durable vitreous coating. The word comes from the Lati ...

coatings are used primarily for art work over copper. More details on copper finishes are available.

Applications

Craftsmen and designers utilize copper's inherent benefits to build aesthetically pleasing and long-lasting building systems. From

s to castles and from homes to offices, copper is used in many products: low-sloped and pitched roofs,

soffit A soffit is an exterior or interior architectural feature, generally the horizontal, aloft underside of any construction element. Its archetypal form, sometimes incorporating or implying the projection of beams, is the underside of eaves (t ...

s, fascias, flashings, gutters,

downspout A downspout, waterspout, downpipe, drain spout, drainpipe, roof drain pipe,Francis Joseph Patry 1974. Roof Drain ArrangementUnited States Patent 3909412< or leader is a

domes,

s, and vaults. Copper is also used to clad walls and other surfaces in the exterior and interior environment.

Roofing

Copper offers a unique character and durability as a roofing material. Its appearance can complement any style of building, from traditional to modern. Its warmth and beauty make it a desirable material for many architects. Copper also satisfies demands of architects and building owners regarding lifetime cost, ease of fabrication, low maintenance, and environmental friendliness. Curoofhecksherjeh

The installation of copper roofing is a craft requiring experienced installers. Its

and malleability make it a compatible material to form over irregular roof structures. It is easy to hammer or work into watertight designs without caulk or gaskets. Domes and other curved roof shapes are readily handled with copper. When properly designed and installed, a copper roof provides an economical, long-term roofing solution. Tests on European copper roofs from the 18th century showed that, in theory, copper roofs can last one thousand years. A Japanese small shrine with a copper sheeting roof at Shinjuku Tokyo 2020 6 25

A Japanese small shrine with a copper sheeting roof at Shinjuku Tokyo 2020 6 25

Another advantage of copper roofing systems is that they are relatively easy to repair. For small pits or cracks, affected areas can be cleaned and filled with

. For larger areas, patches can be cut and soldered into place. For major areas, the affected copper can be cut out and replaced using a flat locked soldered seam. Copper roofs can be designed to meet or surpass other materials in terms of energy savings. A vented copper roof assembly at

Oak Ridge National Laboratories Oak Ridge National Laboratory (ORNL) is a U.S. multiprogram science and technology national laboratory sponsored by the U.S. Department of Energy (DOE) and administered, managed, and operated by UT–Battelle as a federally funded research and ...

(U.S.) substantially reduced heat gain versus stone-coated steel shingle (SR246E90) or

asphalt shingle An asphalt shingle is a type of wall or roof shingle that uses asphalt for waterproofing. It is one of the most widely used roofing covers in North America because it has a relatively inexpensive up-front cost and is fairly simple to install. ...

(SR093E89), resulting in lower energy costs. Types of copper roofs include: Standing seam roofing is composed of preformed or field-formed pans. The pans run parallel to the slope of the roof and are joined to adjacent pans with double-locked standing seams. Copper cleats locked into these seams secure the roofing to the deck. Batten seam roofing consists of copper pans running parallel to the roof slope, separated by wood battens. Battens are covered with copper caps that are loose-locked into adjacent pans to help to secure the roofing. Cleats attached to the battens secure the roofing pans. Transverse seams are required to join ends of preformed pans. Horizontal seam roofs, also called the Bermuda style, consist of copper pans where the long dimension runs horizontally across a roof, attached to horizontal wood nailers. A step is used at each nailer to allow adjacent pans to lock effectively. The height and spacing of the steps enable different appearances. A common design for a chevron roof is based on a batten seam construction to which auxiliary battens are attached. With proper design, decorative battens can have almost any shape or size and run in any direction. Flat locked and soldered seam roofing systems are typically used on flat or low-pitched roofs. They are also used on curved surfaces such as domes and barrel vaults. Flat seam unsoldered copper roofing is a shingle-like option for high slope applications. Mansard roofs are used on vertical or nearly vertical surfaces. For the most part, these roofs are based on standing seam or batten seam construction. Long-pan systems (pans and seam lengths greater than ) accommodate the cumulative expansion stress over long spans of copper sheets. These installations can be complicated due to the length of roof pan versus seam length, cleat design and spacing, and the physical expansion characteristics of copper sheets. This expansion must be accommodated by fixing the pan at one end (which accumulates the expansion at the loose end) or by fixing the center of the pan (which accumulates half of the expansion at both free ends). In addition to panels, copper roof tiles can add uniqueness to a roofing system. They can be used on any roof shape and in all types of climates.

Flashing

While most modern construction materials are fairly resistant to moisture penetration, many joints between masonry units, panels, and architectural features are not. The effects of natural movement due to settlement, expansion, and contraction may eventually lead to leaks. Copper is an excellent material for flashing because of its malleability, strength, solderability, workability, high resistance to the caustic effects of mortars and hostile environments, and long service life. This enables a roof to be built without weak points. Since flashing is expensive to replace if it fails, copper's long life is a major cost advantage. Cold rolled hard temper copper is recommended for most flashing applications. This material offers more resistance than soft copper to the stresses of expansion and contraction. Soft copper can be specified where extreme forming is required, such as in complicated roof shapes. Thermal movement in flashings is prevented or is permitted only at predetermined locations. Flashing installed incorrectly can promote line corrosion and shorten the life of valley flashing, especially in acidic environments. The risk is most prevalent at the leading edge of shingles where the shingle edges rest on the copper flashing. Through-wall flashing diverts moisture that has entered the wall before it can cause damage. Counterflashing diverts water to the base flashing, which, in turn, diverts it to other materials. Various types of copper flashings and copings exist. Diagramatic explanations are available.

Gutters and downspouts

Leaking gutters and

downspout A downspout, waterspout, downpipe, drain spout, drainpipe, roof drain pipe,Francis Joseph Patry 1974. Roof Drain ArrangementUnited States Patent 3909412< or leader is a

seacoast environments or in areas with acid rain or smog, copper gutters and downspouts can provide 50 years or more of service. Downspouts can be plain or corrugated, round or rectangular. cold rolled copper is typically used. Decorative designs are also available. Gargoyle rain spout

Hung copper gutters are supported by brass- or copper brackets or hangers, or by brass straps. Copper gutter linings are often built into wood framed supporting structures. Scuppers are used to provide an outlet through parapet walls or gravel stops on flat and built-up roofs to allow drainage of excess water. They can be used in conjunction with gutters and downspouts to divert water flow to the desired location. Copper roof sumps are generally used for draining small roof areas such as canopies. Roof sump drains are not recommended for general roof drainage systems. LG Leaderhead 045

One of the disadvantages of copper is its propensity to stain light-colored building materials, such as

marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Marble is typically not foliated (layered), although there are exceptions. In geology, the term ''marble'' refers to metamorphose ...

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

. Green staining is particularly visible on light-colored surfaces. Lead-coated copper can result in a black or gray stain that may blend well with lighter building materials. Staining can be reduced by collecting runoff in gutters and directing it away from the building via downspouts or by designing drip edges to help reduce the amount of copper laden moisture that comes into contact with material below. Coating the adjacent surface of the porous material with a clear silicone sealant also reduces staining. Staining may not develop in areas of rapid run-off due to the short dwell time of water on the copper.

Domes, spires and vaults

There are many types of copper domes,

s, and vaults, both with simple geometries or complex curved surfaces and multi-faceted designs. Examples include circular domes with diagonal flat seam systems, circular domes with standing seam systems, circular domes with flat seam systems, conical spires, flat seam roofing on octagonal spires, standing seam barrel vaults, and flat seam barrel vaults. Information about steps for dome panel layouts and specifications for copper constructions is available. Copper-clad spire at the Saïd Business School Oxford

Copper-clad spire at the Saïd Business School Oxford

Wall cladding

Copper cladding has become popular in modern architecture. The technology enables architects to incorporate visually desirable features into their designs, such as embossed or shaped-metal cladding. Cladding enables structures to be made with much less weight than solid copper. composites weigh , only 35% as much as solid copper of the same thickness. Copper cladding is used in building exteriors and indoor environments. On building exteriors, copper cladding sheets, shingles, and pre-fabricated panels shield buildings from the elements, acting as first line of defenses against wind, dust, and water. The cladding is lightweight, durable, and corrosion resistant, which is particularly important for large buildings. Common interior applications include

lobby Lobby may refer to: * Lobby (room), an entranceway or foyer in a building * Lobbying, the action or the group used to influence a viewpoint to politicians :* Lobbying in the United States, specific to the United States * Lobby (food), a thick stew ...

walls,

s, column facings, and interior walls of elevator cabs. Copper cladding can be cut, routed, sawed, filed, drilled, screwed, welded, and curved to form complex shapes. A variety of finishes and colors are available. Flat, circular, and unusually shaped walls can be covered with copper cladding. Most are field-formed from sheet material. They can also be pre-manufactured. In addition, engineered systems such as insulated panels, non-insulated honeycomb panels, copper screen panels, and structural wall claddings are available. Horizontal copper siding provides a relatively flat appearance with fine horizontal lines. Beveled copper panels have depth for heavy-shadowed effects. Flat siding has minimal shadows. Structural panels are designed to be attached directly to a wall structure without the use of a continuous substrate. Diagonal flat lock panels are used on curved surfaces, such as domes, spires and vaults. Horizontal flat lock panels are basically identical to flat seam roofing applied on a vertical surface. Copper screen panels are a lightweight finish screen that can be perforated or have shaped openings to function as sun or decorative screens. A copper alloy curtain wall is a non-structural outer building covering that keeps out weather. Composite copper cladding is made by attaching copper sheeting to both sides of rigid

thermoplastic A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Most thermoplastics have a high molecular weight. The polymer chains associate ...

sheet.

Several different copper facade cladding systems are available: Seaming technique. This is a vertical or horizontal classical cladding construction used in copper roof and façade designs. Available in sheets and strips, the cladding is fixed with clips. Since water tightness may not be a concern on vertical surfaces, angle standing seams are often sufficient. Double lock standing seams are often not necessary. Links to photographs of horizontal and vertical standing and flat lock seams at the

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's Copper Gateway in

Hungary Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the ...

and of pre-oxidized copper clad seamed facades at the Hotel Crowne Plaza Milano, in

Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

, are available. System shingles. Shingles are pre-manufactured rectangular or square flat tiles for roofs, walls, and individual building components. They have 180⁰ folds along all four borders – two folds towards the external side and two towards the internal side. The shingles are interlocked during installation. The fastening is hidden with stainless steel or copper clips on wood sheeting or trapezoidal panels. Machine notching and folding ensures that the shingles have uniform dimensions. Links to pictorial examples of copper shingles in an exterior and interior environment are available. Panels. Panels are sheets of pre-profiled copper with lengths up to and standard widths up to . They are two-sided cladding elements that can be with or without an end base. Assembly is performed using the tongue and groove principle or by overlapping. Panels can be assembled vertically, horizontally, or diagonally. There are three basic forms: tongue and groove panels laid vertically as level surface facade cladding; tongue and groove panels laid horizontally as level surface facade cladding; and custom panels laid in different directions with visible or masked fastening, flush against the surface or overlapping. Links to representative photographs of golden-colored and patinated-green panels are available. System cassettes. This is a rigid rectangular ventilated wall system consisting of curved or flat metal panels mounted and secured to a supporting structure. All four borders are pre-folded at the factory. Folded edges on every side allow large sheet metal parts to lie even with the cladding surface. Fixing is usually by riveting, screwing, or by using angle brackets or bolt hooks to fix the cassettes directly to the substrate. System cassettes are pre-profiled to meet specific architectural requirements. Links to representative photographs of cassette cladding are available. Profiled sheets. Profiled sheets are well suited for covering large cladding surfaces without joints because of their regular, unimposing profiles. Available in a wide variety of shapes, they are well-suited for new flat roofs, façade and pitched roofs, and renovation work. Profiles available include: sinusoidal wave corrugated profiles; trapezoidal profiles with various geometries; and custom profiles with special geometry and edges. They can be pre-manufactured and specified with embossed patterns or other designs. Special shapes. Special shaped façades are available to impart desired visual effects. Perforated metal sheets are available with a variety of shapes (round, square, oblong, etc.) and arrangements (rectangular, diagonal, parallel width, staggered, etc.). They can be designed to create subtle patterns, 'super graphics,' and text. Mesh and textile structures are also available. Links to photographs of special-shaped cladded buildings are available.

Building expansion joints

Designing for the movement of building components due to temperature, loads, and settlement is an important part of architectural detailing. Building expansion joints provide barriers to the exterior and cover spaces between components. Copper is an excellent material for expansion joints because it is easy to form and lasts a long time. Details regarding roof conditions, roof edges, floors, are available.

Indoor design

Copper aesthetically enhances interior wall systems, ceilings, fixtures, furniture, and hardware by evoking an atmosphere of warmth, tranquility, and calm. Regarding performance advantages, it is lightweight, fire resistant, durable, workable, and non-organic (it does not off-gas). Typical copper-based interiors include panels, shingles, screens,

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, fixtures, and other decorative enhancements. Montreal MReine2 tango7174

Since copper surfaces kill pathogenic microbes, architects who design public facilities, such as hospitals and mass transit facilities, look to copper products as a

public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...

benefit. In recent years, copper

countertop A countertop, also counter top, counter, benchtop, worktop (British English) or kitchen bench ( Australian or New Zealand English), bunker ( Scottish English) is a raised, firm, flat, and horizontal surface. They are built for work in kitchens ...

s, range hoods,

sink A sink is a bowl-shaped plumbing fixture for washing hands, dishwashing, and other purposes. Sinks have a tap (faucet) that supply hot and cold water and may include a spray feature to be used for faster rinsing. They also include a drain t ...

s, handles,

doorknob A door handle or doorknob is a handle used to open or close a door. Door handles can be found on all types of doors including exterior doors of residential and commercial buildings, internal doors, cupboard doors and vehicle doors. There are man ...

faucet A tap (also spigot or faucet: see #Nomenclature, usage variations) is a valve controlling the release of a liquid or gas. Nomenclature United Kingdom * Tap is used in the United Kingdom and most of the Commonwealth of Nations, Commonwealth ...

s, and furniture embellishments have become trendy – both for their appearance as well as for their

antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

properties. ''(See main article:

).'' Copper is joined in indoor environments by butt welding, soldering, rivets, nails, screws, bolting, standing seams, lap seams (with and without fasteners), flat seams, bolted flanges, splines, flush laps, and batten seams.

Green buildings

Sustainable materials are key elements of

green building Green building (also known as green construction or sustainable building) refers to both a structure and the application of processes that are environmentally responsible and resource-efficient throughout a building's life-cycle: from planni ...

s. Some benefits of sustainable materials include durability, long life, recyclability, and energy and thermal efficiency. Copper ranks highly in all of these categories. Copper is one of nature's most efficient thermal and electrical conductors, which helps to conserve energy. Because of its high thermal conductivity, it is used extensively in building heating systems, direct exchange

heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing ...

s, and

solar power Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV) or indirectly using concentrated solar power. Photovoltaic cells convert light into an electric current using the photovolta ...

and hot water equipment. Its high electrical conductivity increases the efficiency of

lighting Lighting or illumination is the deliberate use of light to achieve practical or aesthetic effects. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylig ...

, electrical motors, fans, and appliances, making a building's operation more cost effective with less energy and environmental impact. Because copper has a better thermal conductivity rating than usual façade and roofing materials, it is well-suited to solar thermal façade systems. The first commercial application of a fully integrated solar thermal copper façade system was installed at the Pori Public Swimming Complex in

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...

. The installation is an urban example of sustainability and carbon emissions reduction. The solar façade works in conjunction with roof collectors and is supplemented by roof-mounted photovoltaics that provide 120,000 kWh of heat, an amount of energy equivalent to that used annually by six average family houses in cold-climate Finland. One standard in the

United States Green Building Council The U.S. Green Building Council (USGBC), co-founded by Mike Italiano, David Gottfried and Rick Fedrizzi in 1993, is a private 501(c)3, membership-based non-profit organization that promotes sustainability in building design, construction, and op ...

(USGBC)'s Leadership in Energy and Environmental Design rating system ( LEED) requires that newly constructed buildings include materials containing pre- and post-consumer recycled content. Most copper products used in construction (except electrical materials that require highly refined virgin copper) contain a large percentage of recycled content. See: Copper in architecture#Recycling.

Awards

Award programs highlight copper architecture installations in Canada and the U.S. and in Europe. An International Copper and the Home Competition also exists.International Copper and the Home Competition

/ref> Judged by architecture and copper industry experts, criteria for the awards programs include copper in building design, craft of copper installation, excellence in innovation, and historic renovation.

References

{{Reflist, 30em Copper Architectural design Architectural elements Sustainable architecture Corrosion Roofing materials

History

Benefits

Corrosion resistance

Durability/long-life

Low thermal movement

Low maintenance

Lightweight

Ventilation

Radio frequency shielding

Lightning protection

Wide range of finishes

Design continuity

Antimicrobial

Sustainability

Recyclability

Cost effectiveness

Pure vs. alloyed copper

Selection criteria

Structural considerations

Joining

Sealants

Galvanic corrosion

Natural patinas

Finishes

Applications

Roofing

Flashing

Gutters and downspouts

Domes, spires and vaults

Wall cladding

Building expansion joints

Indoor design

Green buildings

Awards

See also

References