rom ancient times to the mod- annual NACIA awards program. weighs 16 oz. per square foot, and ern day, copper and copper Why the trend? One reason is increased 20-oz. copper weighs 20 oz. per square foot alloys have proven to be reli- interest in . Not only is copper and is, thus, thicker. able building materials that 100% recyclable, the sheet copper used for These virtually pure copper alloys are can withstand the test of time. wall cladding is often created largely from not the only game in town. Think back to European and scrap material, and it can be used over and high school science or history classes and FJapanese temples built hundreds of years over with no loss of its engineering prop- recall the Age. Early civilizations ago still have their original copper roofs. erties. discovered a small amount of mixed Even the nearly 200,000-pound copper- into molten copper creates an exceptionally cladded of Liberty has remained TYPES OF ALLOYS strong, durable : bronze. Although a intact despite over 100 years of corrosive The various colors, surface textures, wide variety of these bronze alloys are still , biting sea winds, driving rains, and product forms of copper allow archi- available today, it’s another copper and beating sun. tects and contractors to constantly create family garnering most of the attention for Now, the protective living is wind- innovative designs. As with other , wall cladding: . are combina- ing its way around the sides of university, there are many intermetallic mixtures of tions of copper and . medical, government, and residential struc- copper with other elements. The most com- Although common brass alloys do not tures and adding to its robust portfolio. mon sheet copper wall claddings use only a have the strength of a bronze, they are Architects and contractors are selecting cop- small number of copper alloys, all of which slightly stronger than the base copper, per as a cladding material for its durability, consist of 99.5% copper (with traces of silver while retaining considerably more mallea- flexibility, and malleability. It is also light- allowed). When considering copper, system bility compared to most bronze alloys. Most weight, fire-resistant, -resistant, designers should specify sheet copper to recognizable for their more golden color that and available in an array of finishes and col- American Society for Testing and Materials increases with the amount of zinc, the metal ors. These attributes have allowed architec- (ASTM) Standard B370. It defines compo- has primarily been used architecturally for tural creativity to flourish beyond the limits sition, dimensional tolerances, mechanical storefronts, doorways, and interiors. Now, of traditional wall cladding systems. properties, and characteristics to ensure the metal is transitioning into one of the It’s a dramatic movement—one that’s that the material with the correct properties most popular copper alloy cladding mate- clearly evident in the submissions for the is specified. rials. Brasses commonly available in sheet North American Copper in The most popular temper designations form include an increasing amount of zinc, Award (NACIA) program, hosted annually for sheet copper for wall cladding are “H00” and thus “gold” tone: C22000 “commercial by the Copper Development Association or “H01” (“cold-rolled” or “1/8 to ¼ hard”) bronze” (10% zinc), C23000 “red brass” (CDA) and the Canadian Copper and Brass and “H02” (“½ hard”) if it’s a system where (15% zinc), C26000 “cartridge brass” (30% Development Association (CCBDA). In fact, higher tensile strength but less malleabili- zinc), and C28000 “Muntz metal” (40% adoption of copper as a wall cladding mate- ty is helpful. It is still common to refer to zinc). ASTM Standard B36 is the appropri- rial has become so prevalent that it often sheet copper thickness in traditional ounce ate standard for brass alloys. It is best to outnumbers roofing submissions in the weight thickness. As an example, 16-oz. refer to brass thickness in decimal inches—

1 8 • I n t e r f a c e n o v e m b e r 2 0 1 5 for instance, “.032 in.” or “.040 in.,” select- bare copper or brass is just a teaser. It rate depends on exposure, of course, but ing a thickness depending on project may look great, but it’s going to change. generally, tones are similar to copper while requirements and availability. Chemicals in the atmosphere cause the emerging more slowly. After many years, it As with any metal (copper or other- metallic surface tone to oxidize, transform- is difficult to tell a color difference among wise), it is important to consider the right ing from orange through deepening russet weathered brass, bronze, or copper alloys. brass alloy based on service conditions and tones, rich browns, to black, and possibly— There are few modern brass alloys con- system design. It is especially important if there is enough exposure—to a blue-green taining percentages of aluminum, specially for design professionals and product engi- patina. Hues can vary from panel to panel formulated, which retain a golden tone con- neering staff to review product use with or perhaps even within the bounds of a siderably longer. alloy-producing technical staff when consid- panel. The Irving Convention Center at Las ering brass alloys over 15% zinc, especially In industrial and seacoast atmospheres, Colinas, in Irving, Texas, which won a in a salt-spray zone, in a high-pollutant the natural patina generally forms in five to 2015 NACIA award, is covered with a mill- area, or when the product may experience seven years. In rural atmospheres, where finish copper façade. The raw “red” copper bending or cyclical stresses. There are spe- the quantity of airborne dioxide is rel- surface is already moving through a long cial processes and alloy formulations, less atively low, patina formation may not reach process of patination. Since wall surfaces seen but more appropriate, for extreme con- a dominant stage for 10 to 14 years. In are vertical and atmospheric conditionals in ditions (such as naval or admiralty brass, arid environments, the basic patina central Texas are more arid than most east- developed for saline conditions.) may never form due to the lack of sufficient ern areas of North America, the wholesale moisture to carry the chemical conversion weathering past the deep brown/black hues PATINATION process to completion. The protective chem- will be extremely slow. Designing with copper often involves ical reaction occurs when a corrosive attack For centuries, builders have sought to designing for the long term, both in relation of airborne sulfur compounds to a hasten the weathering process by chemical to appearance and performance. Although gradual change in the surface color until means. Because of the number of variables it’s possible to paint copper, most prefer the equilibrium is reached and the change is involved, chemically induced are natural weathered appearance. It’s free, gets stabilized. prone to problems because of lack of adhe- better with time, and never needs recoating. When exposed to the elements, brass- sion, excessive staining of adjacent mate- The metallic sheen of recently installed es and weather, too. Weathering rials, and inability to achieve reasonable

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7.50W X 5H.indd 1 8/3/15 12:54 PM n o v e m b e r 2 0 1 5 I n t e r f a c e • 1 9 color uniformity over large surface areas. easy-to-install flat-seam copper panels are Copper’s malleability and workabil- Consider these potential shortcomings proving the most popular style. With these ity, combined with adaptability of when specifying such chemical treatments. traditional systems, concealed cleats attach the traditional standing-seam sys- Limitations of field-applied chemi- relatively thin 16-oz. or 20-oz. sheet copper tem, allow unique shape and panel cal treatments prompted copper mills to panels to a solid, smooth, nailable sub- widths, which are difficult to achieve research and develop prepatinated copper strate. Local contractors often fabricate with more common metals. Double- sheet products. Their proprietary methods and install these proven systems, saving lock, standing-seam copper panels involve a chemical conversion process to an extra layer of shipping-related costs cover both the third- and fourth- force a chemical patina at the top molecular and adding flexibility for customization and floor vertical walls and mansard surface of the copper sheet. Significantly, adaptation to site-specific conditions. roof. Standing-seam panel vertical prepatinated products are created in a As with roofing, edge condition and joints line up with the windows on controlled factory environment, removing penetration flashing require special design the third floor—a critical require- the guesswork involved with field-applied attention and supervision at the job site. ment of the design. Because it works chemical solutions. Product manufacturers Fenestrations are especially critical, but great for both walls and roofing, a supply specifications and samples. skilled installers make use of copper’s supe- standing-seam system protects the rior formability and its ability to be soldered building while providing a consistent INSTALLATION to create superior joinery to minimize seal- look. There are two main types of copper clad- ant use. ding systems: traditional and engineered. Although technically “manufactured Standing-seam, batten-seam, flat-seam, Example: Harvard University Tozzer systems,” copper shingles and corrugated and corrugated panel systems are common Library, Cambridge, Massachusetts, systems fit into the “traditional” category forms of traditional installation. Curtain a 2015 NACIA award-winning proj- based on requirements for a solid substrate. wall and copper screen panels are common ect (Photos 1 and 2) Initially intended for roofing, copper forms of engineered installation. shingles see new life as wall cladding, Architect where their distinctive shapes and stiffening Traditional Kennedy & Violich Architecture Ltd. The most popular methods to adapt Boston, Massachusetts sheet copper alloy material to wall cladding utilize the same proven systems devel- Sheet Metal Contractor oped for roofing, but simply applied to a Gilbert & Becker Co., Inc. vertical surface. Both standing-seam and Dorchester, Massachusetts batten-seam systems are common, but the

Photo 2 – The copper roof of the Tozzer Library. Photo by Alex Alpert.

Photo 1 – The Harvard Tozzer Library, on the campus of Harvard University in Cambridge, Massachusetts, at dusk. Photo by John Horner.

2 0 • I n t e r f a c e n o v e m b e r 2 0 1 5 Photos 3 to 5 – The 4143 Buena Vista Project, located near downtown Dallas, Texas, was a 2010 NACIA award-winning project. Photos by Charles Smith.

stampings add extra visual texture. A solid substrate covered with under- layment material provides a secure attachment point. Individual shingles are small in comparison to panel-type systems, like standing-seam; so ther- mal movement is not as much of a concern as with larger panel systems. Galvanically compatible (such as stain- less or copper) fasteners penetrate an edge of each shingle. The overlying course of shingles overlaps each row of fasteners, shedding water. There are some variations to this general theme, so check with each shingle manufac- turer for exact installation recommen- dations. Copper corrugated panel systems are popular, too. These are the same corrugated panels we see (generally in galvanized steel) on industrial or agri- cultural buildings, but with the distinc- tive look and long-term performance of copper. Corrugated copper panels have long been available for roofs and walls, although these systems were never as

n o v e m b e r 2 0 1 5 I n t e r f a c e • 2 1 Photo 6 – Close-up of the copper on the University Center of the New School. Photo by James Ewing.

Photos 7 – The University Center at the New School in New York, New York, won an NACIA award in 2015. Photo by James Ewing. (See also the cover of this journal.)

common as traditionally seamed panels, such as standing-seam. Special fasteners, designed with a gasket at the base of their heads, help prevent leaks. Proper fastener installation and ultimate replacement schedules are critical. The washboard-like appearance and installation ease inherent to corrugated cop- per are incomparable.

Example: 4143 Buena Vista Project in Dallas, Texas, a 2010 NACIA award-winning project (Photos 3 to 5)

Architect Ryan Wommack provide privacy for the homeowners. ited areas. Whether the engineered system Dallas, Texas Natural materials, such as copper, is attached to an underlying structural grid allow the project to enmesh itself or hung curtain-wall style off the build- Sheet Metal Contractor into the world of the trail, as they ing, it’s important to coordinate thoroughly Beach Street Metal naturally change over time. Copper’s with the manufacturer’s engineering staff Dallas, Texas natural patination lends itself per- during design and installation. Credible fectly to integrate with the natural manufacturers provide considerable tech- Natural-aging, corrugated copper aesthetics along the trails. nical and design expertise to help achieve a wall cladding assures that these distinctive look and long-term performance. townhomes coordinate with the Engineered Engineered systems are popular for larger- design aspects found on the popular The engineered wall cladding systems’ scale monumental buildings. Katy Trail. Materials are all direct appearance and capability variations are responses to the environment of extreme, from exceptionally smooth, flat sys- Example: University Center, The the trail: vertical corrugated copper, tems of thick copper, to composite copper- New School, New York, New York, a Milsap stone (used in earlier Work clad material; through deeply brake-formed, 2015 NACIA award-winning project Projects Administration projects textured systems to perforated copper pan- (Photos 6 and 7) along the trail), and ipe wood screens els that allow diffused light to reach inhab-

2 2 • I n t e r f a c e n o v e m b e r 2 0 1 5 Photo 8 – Irving Convention Center at Las Colinas was a 2015 NACIA award-winning project. Photo by Tex Jernigan.

Photo 9 – Irving Convention Center is in Irving, Texas. Photo by Tex Jernigan.

Architect Skidmore, Owings & Merrill LLP New York, New York

Sheet Metal Contractor Gamma Concord, Ontario

Located at the inter- section of Fifth Avenue Photo 10 – The and 14th Street in natural copper Manhattan, the Uni- skin wraps versity Center reflects the building’s and reinforces the exper- exterior and imental nature of The creates a New School and creates dynamic, a dialogue among the changing campus community, the appearance local neighborhood, and as the light the city. The 16-story shines through. building is enveloped Photo by Tex by brass, which helps Jernigan. to mediate between the cast- façades of the Ladies’ Mile built building, designed by Joseph Example: Irving Convention Center Historic District to the north and Urban and built in 1931. The façade at Las Colinas in Irving, Texas, a the brownstones of the Greenwich materials encompass 35% glass and 2015 NACIA award-winning project Village Historic District to the south 65% brass, weathered to a gold- (Photos 8, 9, and 10) and west. The exterior design of the en-brown color by the wall system University Center highlights activity manufacturer to age in a distin- Architect within the building by showcasing guished way and to grow darker Studio Hillier the three primary egress and com- brown over time. Considering the Princeton, New Jersey municating stairs on each of its three characteristics of the façade’s insu- main façades. Strong horizontality of lation and the specifications of the Sheet Metal Contractor the façade echoes the horizontal glass itself, the thermal envelope is A. Zahner Company bands of black and white brick in designed to maximize daylight while Irving, Texas the New School’s original purpose- minimizing heat gain.

n o v e m b e r 2 0 1 5 I n t e r f a c e • 2 5 The Irving Convention Center is a ciated component materials, and the instal- systems and structures—and as evident 100,000-sq.-ft. (9,290 m2) entertain- lation itself (wall cladding often involves from the examples profiled herein—cop- ment palace covered in 150 tons (136 scaffolding or special lift trucks). When all per is increasingly being used for a wide tonnes) of milled, perforated copper the costs are considered, any upcharge for variety of contemporary and exciting new panels. Copper was chosen for the premium copper material may represent installations. Many of these still rely on the LEED-certified project’s building only a fraction of the total installed system. very characteristics that have long made façade because it is natural, light- Naturally, calculations are site-specific, so copper the premier material in the archi- weight, and low-maintenance. At first estimators must consider building design tectural metals industry for centuries, and glance, the material seems impos- and economic conditions on a case-by-case will continue to do so in many new shapes sible. From a medium distance, the basis. When a building owner considers and forms. metal surface seems to float in space the overall product installation costs, true For more information about the differ- because the circular shapes are potential material life (not manufacturer’s ent types of copper applications, to refer- pieced together via slight “bridges” “warranty”), lack of maintenance, and end- ence the – Design or connecting sections of copper. The of-life value, copper-based sys- Handbook, and to view past recipients of the effect is that from a near distance, tems rise to the top. NACIA award program, visit CDA’s website the copper circular sections of the As the material of choice for many his- at www.copper.org. perforation appear to float, offering toric and traditional types of architectural transparency and illusion. Stephen Knapp Larry Peters is a Copper’s natural beauty and self-protec- is the program project manager tive natural finish, performance, durability, manager of the for the CDA. His long service life, and recyclability make Sheet, Strip, and responsibilities it a superior that can Plate Council for include providing be adapted and utilized for a wide variety the CDA, and training and tech- of contemporary and cutting-edge applica- the executive di- nical assistance to tions. Traditionally, copper has mainly been rector of the architects, interior utilized for roofing, flashing, and gutter Canadian Copper designers, contrac- systems. However, these are the qualities & Brass Develop- tors, engineers, that ensure mankind’s oldest metal, copper, ment Association and others inter- (CCBDA), the na- ested in copper remains an important building material. Stephen Knapp Larry Peters Finally, a concern we’re hearing over tional trade asso- and copper alloy and over again is economy—not just the ciation in Canada for the copper industry. material for building . A 1987 long-term “life cycle” economy for which He is also involved with guiding the market graduate of West Point, Larry has spent copper is known—but installed cost, too. development and promotional efforts for a the past 19 years working exclusively with Relatively lightweight copper wall cladding wide variety of copper and copper alloy . Peters travels exten- systems often cost less than many masonry applications such as tube and , sively for the CDA, educating the industry options. This calculation involves the cost electrical, renewable energy systems, and on the benefits and proper uses of copper in of the underlying structure, all of the asso- energy-efficiency technologies. construction.

Immigration Slow-Down Fuels FEDERAL Construction Labor Shortage CONTRACTORS GET RAISE The U.S. construction industry has lost 570,000 experienced Mexican-born The new minimum wage for federal workers since 2007, according to a report by homebuilding analyst firm John contractors and subcontractors will Burns Real Estate Consulting Inc. Such workers accounted for 1.32 million jobs in 2014—down from 1.89 million seven years earlier. While 40% of roofing be $10.15 per hour starting January contractors report they are having trouble finding enough skilled workers, 1, 2016. The increase does not other construction sectors are faring even worse. affect the federal minimum wage, A number of reasons are given, including an improving Mexican economy which remains at $7.25/hour. The and better exchange rates, increased e-verification technology, and stepped- old contractor rate was only 5 cents up border enforcement and deportation levels. These have combined to lower, at $10.10 per hour. The raise produce a 67% decline in immigration from Mexico since 2006. was based on the annual percentage All of these factors are contributing to increased construction costs due to increase in the Consumer Price labor shortages. Index for Urban Wage Earners and — D+D News Clerical Workers.

2 6 • I n t e r f a c e n o v e m b e r 2 0 1 5