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Home , Architectural metals, Copper in architecture, Patina

COPPER IN

Facts on Characteristics and Usage of for Architects

COPPERCONCEPT.ORG 1 INTRODUCTION CONTENTS

Copper was one of the first used by Visually, the aesthetic qualities of copper materials In these days when ecological considerations in INTRODUCTION 2 mankind and has a very long tradition in add character and quality to any project, whilst relation to the choice of materials architecture – the Romans used golden to lightweight nature of their structure permits have joined aesthetic and economic aspects, CHARACTERISTICS cover the of the Pantheon and many of the creative and cost-effective structures to be the impressive and environmental great churches of medieval Europe were covered designed. credentials of copper have been clearly • Natural Occurrence of Copper and its Role with opper. Its distinctive green still plays a demonstrated. Copper products include high in Human Health 4 major part in the skylines of most European cities, The natural development of a patina, with colours levels of recycled materials, saving on energy and • Longevity 6 demonstrating timeless and enduring qualities. changing from red to chocolate brown, and greenhouse gases, and contributing to the circular • Physical and Mechanical Properties 8 eventually to the distinctive light green, is a unique economy. In addition, copper scrap can be re-used • Sustainability and Green Credentials 10 Nowadays, copper can provide a complete external characteristic of copper. Prefabricated systems ad infinitum without any loss of performance or • Compatibility of Copper with Other skin, wrapping around complex building forms with offer a wide variety of solutions, while perforated qualities. Building Materials 14 material continuity. Surfaces can be flat, curved or and expanded copper sheets add new possibilities faceted and used at any inclination or pitch, and in for transparency. ARCHITECTURAL QUALITIES any environment. But also, many designers have been keen to explore new manifestations of copper. WHY COPPER? • Colour and Patina 16 In addition, there is growing interest in the use of • Copper Alloys Used for Architecture 18 copper for . 1. natural material STRUCTURE AND INSTALLATION 2. environment-friendly There are many reasons to consider copper and copper alloys for architectural projects and not 3. maintenance-free • Roofing Systems 20 simply because their unique properties make COPPERCONCEPT.ORG 4. durable, long lasting • Façade and Wall Cladding 26 them extremely malleable and versatile building 5. 100% recyclable • Drainage Systems 36 materials to work with. The broad range of Copper is introduced worldwide as • Substrates 38 modern material for roofing and cladding 6. -resistant architectural possibilities offered by this natural 7. non combustible • External Climatic Effects 40 material and its alloys allows for singular design, applications. Some of the world’s most • Thermal Movement 41 and conventional thinking to be challenged. distinguished modern architects have relied 8. waterproof on copper including Frank Lloyd Wright, 9. proven architectural material INTERRELATIONS WITH BUILDING PHYSICS Alvar Aalto, , Herzog & de • malleable, not rigid Meuron and Foster & Partners. To see copper Maersk Building, Copenhagen, Denmark • lightweight • General Considerations 42 Front Cover: The Christie, Manchester, UK Architect: C.F. Møller references in contemporary architecture visit • Evaluation 45 copperconcept.org or scan QR code. • homogeneous material AFL Architects Photo © Adam Mørk • timeless, living surface INTERIOR DESIGN 46 • colorful and varied Back Cover: Novotel Paddington, London, UK The facade is built up in the form of a grid Dexter Moren Associates comprising storey-height window fields that • creative and unique break up the building’s large scale.

2 2019 COPPERCONCEPT.ORG 3 CHARACTERISTICS

NATURAL OCCURRENCE OF COPPER AND ITS ROLE IN HUMAN HEALTH

Copper exists naturally in the environment, being Copper sheet exposed to atmospheric conditions It is estimated that only 1% of the overall amount an essential trace element for all living organisms. gradually form a protective surface layer, also of copper that enters into the environment from Copper is needed for growth, development and known as patina, that extends the service life of anthropogenic sources can be attributed to functioning of the human body and must be the material. This surface is complex, very durable copper from architectural surfaces. Research obtained from food and water as part of a balanced and stable. So stable that only a very small amount also shows that the bioavailable portion of copper diet. It is regulated by homeostasis and does not of material is lost over a long period of years of in the runoff is quickly and considerably reduced accumulate in the food chain. exposure to rain and other forms of precipitation. as copper ions react with the environment – for example, in contact with solid surfaces such as As a naturally-ocurring element, copper can be pavement, or rainwater pipes – forming found in the Earth’s crust – at a concentration non-available complexes and compounds in the of about 67 parts per million – as well as in immediate proximity of the roofs and facades. freshwater and seawater, from minute trace Reactions with organic matter, such as decaying element levels through to rich mine deposits. It leaves, could reduce the bioavailable portion even is not persistent, bio-accumulative or toxic to the more. environment and should not be mistaken with artificial chemicals or toxic , which This is indicated by the fact that runoff and can accumulate in humans, sea life and plants. discoloration appear always on a relatively short Copper is heavy by its density (8,94 g/cm3), but this length, after rain water from gutter touches has nothing to do with hazard or environmental pavement, following the direction of the water. properties. Where copper content of rainwater run low, these strips end, because water doesn’t transport copper anymore. FIND OUT MORE ON THIS TOPIC Most copper is produced from open-pit mines and Another important source of copper is recycled European copper products for architectural https://copperalliance.eu/about-copper/ The copper compounds that form the patina Much scientific research has demonstrated are poorly soluble and very different from water that extensive use of copper to clad buildings is reserves are plentiful with deposits worked in all scrap. Copper is one of the few raw materials applications are produced including high levels soluble copper salts. As a consequence of this environmentally safe. In addition, studies evaluating five continents. Usually, mines operate with copper which can be recycled ad infinitum without any loss of recycled materials, typically 85% or more with concentrations of between 0,2 and 1%, although of performance; there is no difference in the quality scope up to 100%. As well as helping to satisfy the While copper has always been naturally present low solubility, a very small fraction of the patina the dermatological and oral effects of a number of is released from the copper surface during copper compounds have also demonstrated that some of the richest bodies can contain 5-6% of recycled copper (secondary production) and annual demand, copper is a highly eco- in all environments, anthropogenic (man-made) copper. Copper is extracted from ore, mainly mined copper (primary production). efficient way of reintroducing a valuable material emissions have been added in the last centuries precipitation. This is called the runoff. See more in copper roofs and facades do not pose any harm to colour and patina chapter. human health. In conclusion: copper runoff from copper sulphides, and transformed through various back into the economy, saving energy and reducing – for example through the wear of brake pads or processes into high-purity copper (99,99%). CO emissions. the use of salts in agriculture – and it is necessary roofs should not be a matter of concern. 2 to know whether these „new” additions of copper could be a matter of concern.

4 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 5 SUSTAINABILITY AND GREEN CREDENTIALS

European copper products for architectural The copper industry – from to fabrication – For simplification, too many tools have used applications are produced according to EN 1172 spends in the region of 30% of capital expenditure non-robust and unfair assumptions, resulting in The Eden Project: The Core, UK specifications in world class plants with strictly on improving environmental performance. extremely misleading comparisons. Easy mistakes Architect: Grimshaw Architects monitored environmental performance and well- The processing of copper is on a „Continuous to make include: Photo © Peter Cook established recycling routes. They include high Improvement Program” to service customers and levels of recycled materials, typically 85% or shareholders, and comply with current market • comparing energy and cost per tonne rather It is the education centre for the largest plant more with scope up to 100%, saving on energy and policy needs. The industry is responding to the than per m2 of material, thus misrepresenting enclosure in the world, built in the lightest and and greenhouse gases, and contributing to the European Commission circular economy initiative thinner, lighter materials such as copper most ecological way possible circular economy. Copper sheets’ (copper massive) and looks forward to receiving more scrap for • missing the cost and environmental benefits for interaction with the environment has been re-use as the economy becomes more efficient complete construction of lightweight materials assessed under the European REACH chemical at managing material use throughout its life – • using inappropriate life span estimates, policy and has no classification/restriction. especially towards end-of-life. thus adding ‘energy use’ for unnecessary replacement Copper occurs naturally as part of the cycle All these key environmental credentials of copper • disregarding today’s efficient recycling of metals which form in nature, being used by products can be a decisive argument in favour of practices. society and returning to nature or being recycled use in buildings requiring LEED, BREEAM or DGNB for further use by society. The economic value certificates, which are increasingly in demand, As a recommendation, architects should focus their of copper drives recovery and recycling, not just particularly for public buildings. comparisons on: Primary Energy; Ozone depletion of copper but also many other materials during potential; Acidification potential; Eutrophication dismantling and demolition. Copper is long lasting, It is also worth noting the importance of potential; and Photochemical Ozone Creation can be used in challenging environments and environmental rating tools for investment decisions potential. These are impact categories that are GREEN installations are, for the most part, maintenance and their usefulness for looking at the whole well-known, global and mature – rather than BUILDING free resulting in savings in resources, cleaning supply chain and determining where the greatest other lesser known, non-robust and erroneous chemicals and costs. improvements in environmental performance comparative indicators, especially in the field of can be made for a given product. Unfortunately, toxicity, land use and resource use. The recycling of copper is a well-established they have many inadequacies when used to make practice and its extent follows overall consumption comparisons. For comparisons to be worthwhile, GREEN BUILDINGS ON COPPER CONCEPT patterns. This is due to the relative ease, accuracy of the tool and the methodology behind compared with other metals, of re-using both it need to be both robust and fair when comparing To discover more project examples and processing waste and salvaged scrap from eventual two products of very different compositions and FIND OUT MORE ON THIS TOPIC information on green buildings go to demolition, as well as the incentive of copper’s implementations, even if for the same use. https://copperalliance.eu/benefits-of-copper/ copperconcept.org/en/references and turn on value. Copper can be recycled again and again “” filter or scan QR code. without any loss of performance or qualities.

6 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 7 County Administrative Building, Turku, London 2012 Handball Arena - Copper Box, Architect: Risto-Veikko Luukkonen and Helmer London, UK Steenroos Architect: Make Architects Photo © Robert Pinter Photo © Make

The building has been re-clad using the very A key feature of the building is the 3,000m2 same copper material originally installed in the copper cladding, which has 65% recycled 1960s - an impressive demonstration of the content. Architectural copper can be produced extremely long-term value of copper as an asset out of 100% recycled content and can be to buildings. recycled again in the future.

8 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 9 PHYSICAL AND MECHANICAL PROPERTIES

The European Standard EN 1172 - „Copper MECHANICAL PROPERTIES No other roofing material exists with similar While the tensile strength of the so-called soft The strength and hardness of copper can also be and copper alloys: Sheet and strip for building elongation. Accordingly, copper is extremely copper is lower, it is easily deformable and its increased by alloying – that means that copper purposes” specifies the composition and Designation Tensile strength 0,2 % proof Elongation Hardness formable, which makes it the most appropriate minimum flexural radius value is smaller. Half- alloys have less workability (bending with low mechanical properties for copper and copper strength material for cladding complex forms. hard copper is stronger, but less flexible and less radius of curvature) but higher rigidity. They fit sheets and strips used in building construction. Material Material Rm Rp0,2 A0 mm HV bendable. better for facades, where perfect planarity and condition N/mm2 N/mm2 % Copper products (sheets and strips) can be resistance to impact and wear are required, and the Copper is generally applied as a lightweight Symbol Number min. max. min. max. min. min. max. supplied in a range of conditions or „tempers”. For difficult-to-clad forms, where bending of material must be able to support its own weight. covering, requiring less supporting structure than Cu-DHP CW024A R220 220 260 - 140 33 - - These conditions are designated in the Standard sheets, drawing-out of seams, arching or bossing many materials. With a low CuZn0,5 CW119C EN 1172 as soft (R220), half-hard (R240) or hard is required, it is better to use soft material, The coefficient of thermal expansion of copper is H040 - - - - - 40 65 value, properly designed copper roofs and facades (R290). The letter R represents the tensile strength while in the case of continuously plane surfaces, one of the lowest among cladding materials: minimise movements due to thermal changes, R240 240 300 140 - 8 - - (in N/mm2): the higher the value, the stronger and manufacture of cassettes and profiled sheeting 1 m has a thermal expansion of 1.7 mm with a avoiding deterioration and failure. harder the material. half-hard condition is advised. temperature difference of 100 °C. H065 - - - - - 65 95 As evidenced by the following copper-clad projects, R290 290 - 250 - - - - copper can be worked at any temperature and does H090 - - - - - 90 - not become brittle in cold weather: PHYSICAL PROPERTIES OF COPPER CuSn0,15 CW117C R250 250 320 200 - 9 - - Density 8.94 g/cm3 • Capanna Regina Margherita - the highest H060 - - - - - 60 90 mountain hut in Europe, placed at 4554 m, near 1083°C the top of Monte Rosa Massif. R300 300 370 250 - 4 - - Coefficient of thermal 1,7 mm/m ΔT=100K • Svalbard Science Centre - located in the north H085 - - - - - 85 110 expansion of Norway, where in winter months the average Modulus of elasticity at 132 kN/mm² low temperatures fall below -10°C. CuAl5Zn5Sn1 CW309G R400 400 - 170 - 45 - - 20°C H080 - - - - - 80 - In addition, the high melting point of copper ensures that it will not „creep” or stretch in hot CuSn4 CW450K R290 290 390 - 190 40 - - weather, as some other metals do. H070 - - - - - 70 100 Svalbard Science Centre, Norway Copper is also classified as A1 (non-combustible CuZn15 CW502L R310 310 370 200 290 10 - - Architect: Jarmund/Vigsnaes Architects material) in accordance with EN 13501-1; the H090 - - - - - 90 115 Photo © Nils Petter Dale highest ranking available. Copper and copper alloy sheets and strips are non-combustible and The insulated copper-clad skin is wrapped release neither fumes nor toxic gases. In case of around the building, creating an outer shell fire, experience proves that copper acts as a barrier adjusted to the flows of wind and snow passing against the propagation of fire. through the site.

10 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 11 LONGEVITY

Performance, maintenance, service life, and As a consequence of the increasingly higher The resistance of copper exposed to atmosphere recovery value from recycling are factors that maintenance costs of buildings, on the long run has been measured under the supervision of determine the cost of building components. Using it is more economic to work with materials and the American Society for Testing and Materials life cycle costings, copper stands out as a very structures that don’t require much maintenance (ASTM): tests have been carried out to evaluate cost-effective material for roofing and cladding, and which are long-lasting. Copper definitely the effectiveness of passivation, by measuring due to its durability, maintenance-free nature and belongs to this category. the thickness loss of sheets exposed for 20 years ultimate salvage value. to different atmospheres. The results show an Service life aspects, e.g. the need for repair and average yearly loss of 1 μm (one thousandth of Because of its indefinite life and unique maintenance, are also linked with the quality of the millimetre), with the thickness loss decreasing with characteristics, copper is often used on landmark work done on constructing the building. If a first- patination increasing. projects and might be wrongly perceived as an class metal is used, highly-skilled sheet-metal expensive . However, the existing workers should also be used in order to guarantee The lifespan of copper roofing and cladding can cost competitiveness of copper results in its use on a reliable installation. therefore be regarded conservatively as 200 years, an ever wider variety of building types. subject to substrate and structure – and this is Copper’s longevity is due to a complex patination endorsed by experience. Naturally, this has a In case of copper roofing and cladding, investment process. When exposed to the elements, copper significant effect upon comparative whole of life costs are paid once, and no expenses are required develops a protective and sound patina over time assessments in terms of energy consumption, CO2 later. The lifetime of these structures can Centre Culturel Alb’Oru, Bastia, France with self-healing properties. This ensures extreme generation and cost. surpass the potential working life of buildings Architect: DDA Devaux & Devaux durability and resistance to corrosion in virtually and no maintenance is required after installation. Photo © Joan Bracco any atmospheric conditions and, unlike some other In addition, copper is 100% recyclable, without Therefore, the residual value of the material at the , copper does not suffer from losing its original properties or performance. The copper alloy solution offers the further end of the working life of the building should also underside corrosion. Consequently, it is invariably If demolition or renovation is needed, it can be Museum of the History of Polish Jews, advantage of not requiring any maintenance, it Thickness loss of copper (Cu 99,9%) in 20 years be taken into account in the costings. the supporting substrates or structure which recovered, saving natural resources and energy, Warsaw, Poland does not corrode, even when located in a marine (micrometre/year) eventually could fail rather than the copper itself. while maintaining its value. Architect: Lahdelma & Mahlamaki Oy environment. Indeed, copper roofs have been known to perform Marine atmosphere 0,56 - 1,27 Photo © Michał Łagoda well for over 700 years. Industrial atmosphere 1,40 Copper is a material favoured by architects for Industrial-marine atmosphere 1,38 its aesthetics as well as its durability, a life time Rural atmosphere 0,13 - 0,43 in excess of 100 years. “Copper leaves plenty of opportunities for creativity and is known for its exclusivity and uniqueness of realised projects.”

12 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 13 COMPATIBILITY OF COPPER WITH OTHER BUILDING MATERIALS

Corrosion in metallic materials on the outside of Arrangement of copper above or galvanised WINDOWS PLACEMENT IN A COPPER buildings can be caused for two reasons. The first should be avoided, because the copper ions FACADE is of a strictly galvanic type, i.e., when two different washed away in the rainwater which then drains metals are in direct contact. The other is caused by onto the zinc react with it, resulting in accelerated Window types such as wooden windows, copper- runoff from one metal surface onto another metal corrosion of the zinc. The opposite arrangement, of clad wooden windows, bronze framed and plastic surface. zinc above copper, is harmless. However, no direct windows do not normally generate corrosion. contact points between the metals must exist. There are a number of window manufacturers that Due to its placement on the positive side of the are specialists in delivering copper-clad wooden electrochemical series, copper is not negatively It should also be noted that rainwater running off windows. Here, there are many possibilities for affected by other metals. However, if wrongly bitumen exposed to the sun can cause corrosion design effects with the aid of different profile combined, other metals like zinc, problems for various materials – including copper solutions. and steel could be affected by copper. Therefore, – and certain residues washed out of or building structures should be designed in such a mortar can cause copper to take on a blue-green Anodized aluminium windows and windows of way as to avoid contact – both direct and indirect – colour, so it is worth preventing. Also, the wash- lacquered aluminium can also be used. It is, between these metals. off from red cedar shingles can cause metals to however, important to avoid direct contact with corrode. the copper surfaces and make sure that runoff The combination of copper with is from the copper surfaces will not run onto the harmless under most circumstances. Care should aluminium surfaces. To eliminate the runoff effect, be taken in detailing any steel above copper as the windows can be placed deep into the facade ‚’ marks can appear on the copper caused by or alternatively protruding with an outside window rust drips from the steel. flashing. It should be noted that cut aluminium profiles often have an untreated surface where the A combination of copper and aluminium is only cut has been made. These surfaces will have to be Residential house, , possible when the aluminium has an electrically treated to give a lasting corrosion protection. The Netherlands non-conductive surface, after coating or anodising. Architect: Hund Falk Architecten In this way, copper-bearing runoff cannot form Many effective runoff solutions can be reached Photo © Ivan Brodey an electrochemical reaction with the aluminium. with the aid of different types of joints and drop Direct contact between the metals should be aprons. It is usually not the heavy runoffs that A flat wall completely covered with double- prevented by inserting an intermediate layer of create corrosive problems; the ion level in those is sided preoxidised copper tape and flat black non-conductive material or by simply leaving a gap. often low as it is being diluted in large quantities aluminum frames provide an abstract view of of water. Dew and small quantities of rain, on the the former buildings. other hand, often mean aggressive water runoff.

14 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 15 ARCHITECTURAL QUALITIES

COLOUR AND PATINA

When exposed to the atmosphere, the appearance Airborne also increases the rate of Pre-patinated copper is, of course, useful in the of copper surface evolves through several phases SURFACE patination, which therefore takes longer in cleaner field of historic building preservation. But its from installation to the natural development of EVOLUTION environments than in cities or industrial areas. potential is most exciting when considered as a patina – this is a unique characteristic of copper. A The complex combination of factors determines completely modern building material, combining full understanding of this process is important for the nature and speed of development of patination, the distinctive green colour with the freedom of building designers. giving copper unique, living visual characteristics form available with copper. After installation, developing over time in response to local the surface continues to develop in a completely Immediately after installation, oxidation starts on SURFACE EVOLUTION ON COPPER CONCEPT conditions. natural manner being characteristic of copper. copper surface exposed to natural , the influence of which becomes visible very soon. Once in place, copper products come to Many architects and owners want to see the dark Gradually, the surface turns matt and the material life and become more beautiful over time. brown colour or the distinctive green patina right develops a protective layer, changing its To discover more project examples and from the moment of installation, without waiting PROBABLE TIME-PERIOD OF GREEN PATINA colour to russet brown. As weathering progresses information on surface evolution over time go several years or decades for the gradual changes FORMATION over a number of years, the surface increasingly to copperconcept.org/en/references and turn caused by natural weathering – even in situations In rural or upland environment Min. 30-40 darkens to a chocolate brown. on “surface evolution” filter or scan QR code. such as vertical cladding and sheltered surfaces years 2014 where rainwater driven patination might never In city or town environment 15 to 30 years Continued weathering can then result in A brochure on this topic is also available at occur. development of the distinctive green patina – copperconcept.org/en/publications In coastal or industrial 8 to 20 years green-blue in marine environment. The patina layer Different surface treatments are now available environment provides impressive protection against corrosion which create very similar processes to those taking and can repair itself if damaged, defining the place over time in the environment and the leading exceptional longevity of copper cladding. manufacturers are able to provide oxidation and 2016 patination straightaway. A certain amount of rainwater is necessary to form the green patina and its rate of development will Pre-oxidised copper offers the aesthetic depend on the water „dwell time” on a surface. As appearance of an attractive, naturally oxidised a result, the process takes much longer for vertical surface immediately. In addition, it minimises any Meripaviljonki (Sea Pavilion), Helsinki, Finland surfaces than exposed roofs, due to rapid runoff. surface markings which might occur on bright Architect: Arkkitehtitoimisto Freese Oy In coastal areas vertical surfaces patinate quite mill finish copper and can advance the natural Photo © Esko Tuomisto readily. patination process through the effects of sun, rain, snow and wind. The choice of copper recognises the material’s sustainability credentials, long-life, minimal maintenance and beautiful patination. Photos taken 2014 and 2016 (weathered).

16 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 17 COPPER ALLOYS USED FOR ARCHITECTURE

There are more than 400 copper alloys, each with BRONZE In architecture, bronze is appreciated for its rigidity, GOLDEN ALLOY a unique combination of properties, to suit many resistance to wear, long lasting and resistance different applications. Some of them – bronze, An alloy of copper and and a synonym for to corrosion. Its reddish-brown surface, when This is an alloy of copper with aluminium and zinc and golden alloy – are used in architecture, metallic artworks. While artists have long made exposed to the atmosphere, gradually changes to that shows an excellent corrosion resistance and for roofing and cladding, thanks to several use of bronze, architects are now able to make dark brown anthracite in a manner characteristic very high mechanical properties (strength and concomitant factors such as extreme durability, optimum use of this material. It is also well known for bronze through the effects of weathering. The wear resistance), due to the formation of a thin, singular beauty and mechanical resistance. in technology, especially where high resistance patina coating forms much more slowly than with hard, protective oxide layer containing all three to wear is required (such as springs, gears and pure copper. alloy elements. For these reasons, it is also used These copper alloys used in rchitecture also display bearings). in coins – the 10, 20 and 50 euro cents are made of individual characteristics as they weather naturally CuAl5Zn5Sn1. to exteriors. They are installed especially in facades, but they can be exploited for roofs as well. Aesthetically, it has an outstanding golden colour, In addition, their colours can be slightly modified, with very little tarnishing over time, developing for example by applying a wax, in order to provide an elegant and long-lasting, matt gold coloured appealing nuances to the surface. appearance.

BRASS

An alloy of copper and zinc with a distinctive golden BRASS yellow colour. The presence of zinc improves the Ferry Terminal, Stockholm, Sweden mechanical strength and the hardness. Thanks Architect: Marge Arkitekter to this improved strength, brass sheets used in Photo © Johan Fowelin architecture can support better their own weight as well as withstand unexpected impacts. Roofs and walls are clad with burnished brass, GOLDEN ALLOY which harmonises well with the stone and Courthouse, St. Pölten, Austria When exposed to the atmosphere, the original stucco facades in the background and creates Architect: Christian Kronaus surface and gradually turns into dark a unified, sculptural expression. In addition, BRONZE Photo © Thomas Ott brown. Ultimately, it may develop a patina but much variations in surface texture are achieved using Garden Museum, London, UK slower than copper. In addition, brass is really well- different techniques. Architect: Dow Jones Architects Through the inherent richness of the material, suited for interiors and its surface can be treated to Photo © David Grandorge the building gets a pleasant and warm provide a brownish finish. character that varies continuously, depending The pavilions are clad in bespoke bronze on changing light conditions over time. shingles set out to reflect the scale-like quality of the bark of the surrounding plane trees.

18 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 19 STRUCTURE AND INSTALLATION

ROOFING SYSTEMS

The structural formation of metal-plate claddings Through this solution, expansion gaps are formed For continuous fastening along a line, lock strips has been refined in the past centuries on the and trays are able to tolerate dimensional changes are used, which are fixed directly to the substrate basis of characteristics of the material. Cladding caused by the influence of heat without visible on the whole length or spaced continually, and the metals are used in manufactured forms that are deformation, corrugation or other damage. sheets are folded on and hooked in them. thin (0.5-1.5 mm), but have large surface. It is a consequence also of this fact, that the dimension In practice, two types of roofing are common: Batten seam roofing, similar to standing seam of these plates change significantly on the standing seam roofing and batten seam (or batten roofing, is built up from strips, but these are not influence of heat, and as roofing materials, they roll) roofing. fastened directly to each other, but to battens are frequently exposed to even 100°C difference of nailed or screwed on the substrate parallel to temperature. Standing seam roofing is made up of trays the slope line. U-shaped cleats are put under the arranged square to the cornice (i.e. parallel to the battens. The whole batten is then covered with The roofing must accommodate the dimensional slope line) and are connected to each other with batten cladding sheet with drip bordering. changes caused by thermal expansion and at the double standing seams. It is applicable for slopes same time it must fully satisfy requirements for above 3 degrees. This solution is more impervious than standing roof membranes, i.e. they must be waterproof, seams, because joints are positioned higher. It can frost-resisting, durable and strong. Generally, cleats are used for fastening copper be used even in case of 3% slope of a roof. to the substrate, with copper nails where two Sheet metals used for roofing – and copper is neighbouring trays meet. Cleats are folded together Both can be made from trays assembled from outstanding among them – are easily formable with trays to create the seams. Trays are fixed this sheet or strip cut to the length of the rafter or from and leakproof. The dimensions of trays must way, but being an indirect fastening method, the prefabricated, profiled strip elements. be selected and joints formed in ways that they joint allows some movement. must be able to tolerate thermal movement while preventing the infiltration of moisture along these When laying trays, workers must leave gaps joints. of a few millimetres to enable them to accept transversal thermal movement. It is a basic principle in case of any type of roofing Montevergine Sanctuary, Mercogliano, that metal cladding sheets are never fixed in a non- The usage of sliding cleats is a specialty of copper Avellino, removable way directly onto the substrate. Meeting cladding. These consist of two parts capable of Architect: Studio Arch Luigi Picone sheets are adjoined by multiple splicing (seam) to moving off from each other and allow an even each other and are fastened to the surface to be greater thermal motion. The machine-rolled copper sheets have been covered onto fixed retainers (cleats, lock strips) installed onto supporting wooden boards as after folding. double standing seam system.

20 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 21 MAKING OF A SINGLE LOCK MAKING OF DOUBLE LOCK FIXED CLIPS STANDING SEAM TYPES OF SEAMS

FISHTAIL CLIP PROFILED FIX CLIP

FLAT LOCK SEAM

DOUBLE LOCK STANDIG SEAM WITH FIXED FISHTAIL CLIP

ANGLE STANDING SEAM

Sport and Leisure Centre, Budapest, Architect: T2.a Architects DOUBLE LOCK STANDING SEAM Photo © Zsolt Batár ± 300 The Orangery, Huizen, Netherlands HOOKING CLEAT A major sports building mutates its Architect: Braaksma & Roos straightforward rectangular plan into a complex Architectural Office

faceted copper roofspace. 430-600 Photo © ECI

The entire roof is covered in prepatinated copper, same as the bays of the Mansion. Pre- patinated copper perforated screens are used in front of and on east elevation.

GENERAL SCHEME OF STANDING SEAM ROOFING

22 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 23 Another type of roofing is where prefabricated profiled sheets are used, which is akin to fluted Le Safran festival hall, Brie Comte Robert, sheets made of any other metals. It is assembled France from corrugated panels fitted with retainers. The Architect: S.C.P.A. Sémon-Rapaport system allows very quick work on large plane Mandataire de L’Equipe, Brie Comte Robert surfaces in the frame of a previously worked out DUPRE, Saintes system. The result resembles batten seam roofing. 430-600 Photo © KME MAKING OF A BATTEN SEAM The roofing system chosen – beyond any aesthetic Copper sheet has been used for roofing for regards – must be decided by the basic geometry, centuries; this includes copper shingles (or the slope of roof is a determining factor. rhombuses), small-sized metal sheets which have been used for the roofing of , Batten seam roofing or the application of profiled facades and other roof areas. sheets give a sharp-featured image by making large plane surfaces lively. But they are not applicable on arched surfaces or on more complex A varied-texture surface can be installed with roof forms; what is more, the installation of batten GENERAL SCHEME OF BATTEN SEAM ROOFING overlapping scales or shingles, which use the seam roofing is rather labour-intensive. characteristics of the metal. It comprises uniform INSTALLATION OF BATTEN SEAM ROOFING elements sold by the factory or made on-site. In Highly complicated roof forms can be relatively its size and texture it resembles small-tile slating, easily covered with standing seam roofing. The but its structure is different. Diamond, rectangle result will show a homogenous picture, where trays or square trays are folded on their four edges in are less accentuated. The width of trays and the a way that single lock seam joints overlay and are thickness of sheets are determined by aesthetic hooked into each other on all sides. The elements considerations and by the dimensions and relations are fastened with cleats, one by one. Because their of the roof, the location of roof superstructures and small size and seamed edges make them rather – last but not at least – the wind force affecting the rigid, the whole covering can be fastened to a roof. STYLE A STYLE B batten frame following the distance of retainers. When selecting a roofing system, the designer must consider the reliability of the structure, its feasibility, etc., taking stock of all architectural and aesthetic requirements. Rosneft Copper Roof, Moscow, Russia Architect: Archexpert Photo © Savros

Unique three-dimensional copper shingles for a stronger structural effect crafted with self-built machines by a local specialist.

24 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 25 FAÇADE AND WALL CLADDING

With the twentieth century came a transformation FACADE SYSTEMS from copper’s historic role as a durable roofing material to a flexible architectural skin over any STANDING SEAM AND PROFILED SHEETS surfaces, including walls. Copper sheets can be installed in facades with the Copper can provide a complete external skin, same seaming techniques used for roofing – in wrapping around complex building forms with most cases angle standing seam is acceptable material continuity. Surfaces can be flat, curved as water tightness is not a major concern on or faceted and used at any inclination or pitch, vertical surfaces. In addition, it is possible to use and in any environment. Alternatively, it can give various types of profiled sheets (sinusoidal wave, distinctive character to individual façade elements, trapezoid), including custom-made profiles. particularly when used in conjunction with other high-quality materials such as stone, brick, glass PROFILED SHEET and wood.

Apart from standard copper sheet, there are other ANGLE STANDING SEAM CLADDING copper products that create extra dimensions of modulation, texture and transparency for architectural surfaces. Installation techniques and systems also help to define architectural character – there is an extensive range of factory pre- fabricated systems for facades, as well as copper sheets and strips.

The cladding construction presented here follows the concept of a bracket mounted, ventilated cladding, creating an optimised system that securely envelops the closed, wind-tight inner construction. A ventilation area is generally required for several reasons: to reduce humidity, Kunstmuseum, Ahrenshoop, Germany Museum of Fire, Zory, Poland to allow penetrating rainwater to diffuse out of Architect: Staab Architekten Architect: OVO Grąbczewscy Architekci the construction, to create a capillary separation Photo © Christian Richters/ KME/ MN Photo © Tomasz Zakrzewski / archifolio between the cladding and the breathable thermal insulation or support structure and to diffuse The apparently random, animated profiled This unusual building, the Museum of Fire, condensation on the underside of the cladding. surface structure flows continuously with no resembles a flame creeping along the ground - visible offset giving the impression that the Like fire dancing on the ground. whole has been cast as one piece.

26 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 27 SHINGLES PANELS CASSETTES

Shingles offer a distinctive „fish scale” appearance Panels are cladding elements pre-formed on two Cassettes are cladding elements with folded edges with shapes including squares, diamonds, sides that can be assembled vertically, horizontally on all four sides available in a range of rectangular rhomboids and rectangles. These flat tiles are laid or diagonally to give a linear, striated appearance. proportions. They are produced project-wise simply by hanging them and interlocking them with Assembly at the building site is performed according to the specific design concept. Cassette each other, offering a relevant economic advantage. according to the tongue and groove principle or by cladding is suited for larger flat areas, offering overlapping. Individual lengths are as long as 4,000 great flexibility in terms of formats, the layout of Shingles have a 180° folding on all borders – two mm with a width of up to approx. 500 mm. joints and fixing principles. sides are provided with a fold coming forward or with a downstand. All folds and notches are pre- As panels are not laid in contact with the Fixing is usually achieved by riveting, screwing, processed in the factory. This ensures that the underlying structure, it is necessary to put a solid hidden/subsurface fittings or by means of bolt corners of buildings and connections to other material (wood, plastic) between the copper and hooks to fix the cassettes directly to the substrate. constructional elements such as windows and the structure, especially at ground level up to doors are completely weatherproof. approx. 2 m, in order to avoid signs and dents due to possible shocks.

Clarion Hotel Post, Gothenburg, Sweden Special Education School in Dinkelscherben, Architect: Semrén & Månsson Germany Photo © Lennart Hyse Field Street/Leeke Street, London, UK Architect: Frech & Mair Architekten BDA, Architect: Project Orange Augsburg This was made up of copper in three strip Photo: KME heights – 200, 250 and 300 mm – and three The external façade is clad in oxidised copper different intensities of pre-patinated copper, by ‘scales’ that overlap and soften the dominant Horizontal installed panels with visual gap give a varying the amount of green over the dark brown geometry of the building. specific architectural character of facades. background.

28 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 29 TRANSPARENT STRUCTURES

The copper industry is continuously developing new products in order to enhance the aesthetic merits of copper and copper alloys used in architecture, as well as to expand the freedom that architects can enjoy by working with copper.

One of the latest products are the perforated and expanded copper sheets and strips which add new possibilities for transparency and can be individually manufactured to the vision of the architect.

Perforations on copper sheets and strips offer Communal Stage, Trondheim, Norway many possibilities for singular design, including Architect: HUS arkitekter AS subtle patterns, images and even text. Many Photo © Mathias Herzog different levels of transparency can be created – from almost complete transparency to a subdued Daylight plays on its hand-patinated multi- translucence. layered surface adding richness to this floating canopy, then at night it becomes luminescent in The effect of back-lit facades can be designed very its own right. individually by using a large number of different perforation patterns. There are also virtually no limits to the use of perforated copper and copper alloys as decorative indoor elements. Centre Culturel Alb’Oru, Bastia, France Expanded mesh structures are made by perforating On the building, the use of copper mesh designs Architect: DDA Devaux & Devaux Architectes and then stretching the material to create a metal brings a pleasant lightness to the façade. When Photo © Joan Bracco curtain with functional aesthetic qualities. The installed in front of glass areas, they offer security many different structures of the copper rib mesh in an aesthetic form as well as fascinating The transparent copper alloy mesh facades provide openness and create a solid barrier, impressions from inside and outside. encase open circulation routes around three offering both transparency and mechanical sides of the building, generating external protection. spaces for reading and enjoying the views. At night, the building becomes a glowing beacon with internal shining out.

30 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 31 DYNAMIC FACADES

DYNAMIC The building facade has to protect the building and FACADE to act as its face to the outside world. It must have a durable, weatherproof sealing layer – a surface which protects it against the wind and weather and is simple to maintain. In addition, the outermost layer of the facade must be combined with an DYNAMIC FACADES ON COPPER CONCEPT effective, functional insulating material. To discover more project examples and But in the last few years, another function has been information on dynamic facades go to added to the well-known aesthetic, weatherproof copperconcept.org/en/references and turn on and insulating facades’ functions – the optimization “dynamic facade” filter or scan QR code. of energy consumption. Either through passive shading and ventilation or through complex systems, the building skin transforms dynamically Responding to changes in urban life—both to regulate the internal environment in order to organisational, technological and societal— reduce its energy demands. architects and town planners must innovate. Dynamic copper façades enable modern buildings Of course, copper has a prominent role to play Merchant’s house, Copenhagen, Denmark to interact with their environment, and can limit in dynamic facades. Durable, malleable and Architect: HUS arkitekter AS the use of artificial lighting and heating, regulate scalable, it is a material of choice for architects Photo © Jens Markus Lindhe aeration, light or transparency, and create who innovate in designing functional cladding. In unprecedented visual effects. the form of copper sails or strips, they are able Areas of the copper curtain can simply fold to better manage light and heat, and improve the up to generate a pattern of fenestration energy performance of buildings. In the form of matching that of the adjacent buildings. When a raw surface that evolves over time, the façade closed, the curtain becomes homogenous and gives life to a building and becomes the key to its impenetrable - but then dissolves to reveal the environmental integration. interior with lighting at night.

Conservatoire Claude Debussy, Paris, France Architect: BasaltArchitecture architectes Photo © Sergio Grazzia

A skin perforated by the beat of the melody that emerges and takes shape in the outer walls.

32 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 33 La Monnaie de Paris (Paris Mint), France Architect: AAPP / Philippe Prost Photo © Benjamin Chelly and Aitor Ortiz

Creating an architecture where the chosen Experimentarium - The Helix Staircase, materials evoke the expertise of the Copenhagen, Denmark practitioners working inside the house. Architect: CEBRA Photo © Adam Mørk Copper and its alloys allow great architectural Pegasus Academy, London, UK DESIGN CONTINUITY creativity, and are the go-to materials for functional Architect: Hayhurst and Co. An entirely new architectural setting that brings façades thanks to their malleability and ease of Photo © Kilian O’Sullivan As a roofing material, copper has traditionally science and technology into focus – from the installation. Copper sheets are lightweight, easy been used to form associated elements such as illustration of fluid dynamics on the facades, to work and assemble, aesthetically pleasing and A golden copper alloy frontage announces the flashings, vents, gutters and downpipes. Modern to the spectacular Helix staircase that meets extremely durable without maintenance. A wide entrance to this south London school – recipient design took this further with the growing use the guests as a shining icon immediately upon range of finishes are also available: smooth and of several awards, including Winner of the 2015 of copper for vertical cladding, rain screens passing the main entrance. glossy, perforated, embossed, pure or alloyed, raw Architectural Review Schools Award – unifying and curtain walling, focusing on copper as a or pre-patinated. disparate existing buildings. comprehensive skin to express building form and maintain performance and material continuity. Nowadays, architects continue to exploit this flexibility and freedom of form, with complex shapes made possible by computer-aided design techniques.

34 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 35 DRAINAGE SYSTEMS

A complete roof drainage system is required – The shape and dimensions of a gutter are defined HUNG GUTTER RIDGES In addition, flashings are required to prevent Copper with correctly sized gutters and pipes – for the by the quantity of water to be drained away from moisture from entering the building by diverting Architecture VENTING RIDGE Forum roof to provide effective protection against rain, the roof to the downpipes and by architectural it. Copper is an excellent material for flashing snow, sleet, etc. It is no less important for the roof design requirements. The tendency of the guttering because of its malleability, strength and high COPPER ARCHITECTURE FORUM MAGAZINE drainage system to be designed to withstand the to become blocked due to the accumulation of resistance to the caustic effects of mortars and weight of snow and the formation of ice. rubbish for example, also has to be taken into hostile environments. Since flashing is expensive to CAF magazine shows you the best examples account. replace if it fails, copper’s long life is a major asset of contemporary architecture. Order your The roof drainage system may be based on surface in this application. free printed copy or read them online: mounted gutters and downpipes or on recessed, There are many different types of prefabricated copperconcept.org/en/copper-forum or scan built-in systems, or on a combination of these. system on the market, such as semi-circular and Copper cladding offers a good basis for exterior QR code. rectangular gutters, and lengths of between three lightning protection because the seams create a Gutters and downpipes made of copper must meet and six metres are the most common. A number of conductive covering over the entire surface. Instead the demands of the European standards EN 612 bespoke systems are available as well. of conductor tapes the metal cladding on roofs, and EN 1462. In particular, the standard EN 612 facades and gutters may be used as conducting specifies requirements for gutters and downpipes The distance between gutter hooks should not part of the lightning protection system. For under the usual service conditions, i.e. catching exceed 600 mm. In the case of gutters in exposed further guidance see IEC EN 62305 and national and draining away rainwater, melted snow or ice positions – where large amounts of snow could regulations. water from a building to a drainage system or a collect, for example – the gutter hooks must be sewer outside the building. fitted more closely together (400 mm, for example). The gutter must be fitted with a slope of no less The performance of a gutter and drainage system than 5 mm/m in order to make the water flow away; made with standardized products depends not only a higher slope means a higher flow. Guttering must NON-VENTING RIDGE on the properties of the products, but also on the never be fitted with a backward slope. design, construction and behaviour of the relevant parts of the building. A gutter is generally long and straight, so it may be necessary to use an expansion joint to allow the COPPERCONCEPT.ORG Maintenance, durability and longevity are important gutter to expand and contract. factors to consider when designing gutters and The diversity of surfaces offered by copper At the lowest position of the gutter, downpipe must downpipes. Copper is an excellent choice because and its alloys today is greater than ever. To be connected. The location of the connection must of its low maintenance, high resistance to corrosion see copper references in modern architecture be chosen taking into account local rules, sewage and long life. Even in severe climates such as visit copperconcept.org or scan QR code and system connection, architectural features and marine atmospheres, a well-designed copper choose your language version. rainwater system can provide many years of low aesthetics. Downpipes are attached using pipe maintenance service. union pieces, with a maximum distance of 2 m between pieces.

36 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 37 SUBSTRATES

It is a basic requirement that the substrate for Profiled copper (as well as most types of cassettes) SUBSTRATE FOR FACADES copper sheets and strips must always be smooth, is more rigid than flat sheet on account of their even and strong, letting nails or screws be securely design. This means that an absolutely flat surface The seamed copper-clad wall with facade sheeting fixed. The most common substrates for copper are is not required in respect of bearing strength. in the form of strips or sheets requires a firm steel trapezoidal sheet, insulated panels and wood, However, it is important for the substrate to be substrate, as does traditional copper roof, and but other materials that meet these criteria can sufficiently even and flat to ensure that the surface this substrate must be able to withstand dressing be used as substrates as well. It is also necessary of the sheet metal does not become uneven or of the sheet and permit clips to be used for fixing to be sure that the substrate is compatible with dented. purposes. In the case of profiled sheets, panels copper – for example, the wood may contain fire and cassettes, the technical requirements for the retardant, preservatives or insect-killers. Substrate and copper must be separated with substrate are more or less the same. a tangential separation underlay, which can Concrete and brick structures (e.g. coping) should allow movement in the copper sheeting, provide Irrespective of whether the building is new or being be covered with a proper layer in order to level a temporary weathering for the building during renovated, the underlaying surface must be level. their surface, as uneven areas can easily be seen construction, deal with irregularities on the Nowadays, adjustable metal spacers are available in the finished covering or underlying walls, facade substrate surface and absorbs sounds caused by which permit even old, uneven surfaces to be fitted decorations and windows, the mortar screed is wind or rain at a great extent. simply so that they are level. enough of a foundation. Hard mineral wool can be used under certain conditions. There are several types of separation underlay. What is important: it must be durable and must With warm roof , rigid insulation ensure easy diffusion. In most circumstances, panels can provide a suitable substrate. However, industrial felt is the preferable solution, because fixing becomes more complicated. There are two this material has very good tangential, noise basic approaches: either to provide two layers of barrier and vapour diffusing properties. insulation, each laid between battens, with the second laid counter-battened to the first; or to use specially extended fixing clips which pass through the depth of the insulation to an additional nailable substrate beneath. For fastening copper or copper alloy sheets to the substrate copper nails or stainless steel screws, clamps or rivets are The Lizard Lifeboat Station, UK All Saints’ Academy, Cheltenham, UK recommended to avoid corrosion problems. Architect: PBWC Architects Architect: Nicholas Hare Architects LLP Photo © Geoff Squibb (Cornish Pixels) Photo © Nicholas Hare Architects LLP

The building is predominately timber frame with The cladding of the chapel was undertaken glulam-curved members providing the iconic with real craftsmanship, the copper shingles Lofts Antwerp, Belgium shape. The double skin roof is finished in copper gradually reducing in size to accommodate the Architect: Hub trays with standing seam joints. conical shape reaching through the atrium roof. Photo © Hub / Platteau Bvba

38 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 39 EXTERNAL CLIMATIC EFFECTS THERMAL MOVEMENT

RAIN AND SNOW WIND Facade cladding and roof covering may be subject FIXED ZONES AND MOVABLE ZONES to great temperature fluctuations both during Roofs and exterior walls must not be permeable Wind loads are the strongest, most frequent hostile single 24-hour periods and over the course of a A zone of fixed clips is necessary on a roof covered to rainwater and snow. Where hard driving rain factors which affect roofs and facades. In areas year. When designing copper structures, movement by long strips to secure the copper to the roof. is expected, special attention should be given to where high winds occur, roof covering and facade and stresses related to temperature variations Sliding clips allow the copper sheet to move, roof slopes, joints and seam details, eaves, ridges, cladding must be carefully designed and sheets must be accommodated; it is important also to take expand and contract. flashings and connections to higher walls. securely fixed to the underlying structure. The into account possible movements in the underlay. density of fixing clips has to be designed according The movements of the strips are assumed Taking into account that a copper cladding is to windload distribution. All materials react: they either shrink or expand to originate from the fixed zone or centre of "discontinuous", proper design and technical when the temperature changes. It is necessary movement (shaded area in the figure below; sliding solution must be followed in order to avoid any If the wind blows directly onto the building, the to take into account the coefficient of thermal clips are placed in the unshaded areas). The fixed infiltration through the sheets. Contiguous sheets strongest positive pressure occurs towards the expansion of each material in order to reliably zone should be 1.5 to 3 m in length, depending on determine the degree of change. A copper sheet POSITION OF THE FIXED CLIPS must be overlapped and bent together, according centre of the windward side. On the opposite the total strip length. In the case of steeply sloping WITH INCREASING ROOF PITCH to well-known techniques, like the standing seam side, the greatest negative pressure occurs at of 1 m has a thermal expansion of 1.7 mm with a roofs, it is appropriate to place the fixed zone at or the batten roll. The choice of the proper joint the corners and upper section of the facade. temperature difference of 100°C. ridges. If the fixed zone is placed in the middle of depends also on the roof slope. The distribution of pressure is also affected the roof, one strip length can be laid upwards from by the direction of the wind, the turbulence, Flat sheets can absorb thermal movement the fixed zone, and another can be laid downwards The height of the standing seam should be 25 mm the geometrical design of the building and the across the standing seams provided the seams from it. at least, and the direction of the bending must take topography of the surrounding area. are designed to accept the appropriate amount into account also the direction of the main wind. Country House, Segovia, Spain of expansion. Longitudinally, the sheet is able to If the strips are locked in position at more than When the slope of the roof is less than 7°, sealing TEMPERATURE Architect: Forero Arquitectura move freely if it is attached using sliding clips and one point lengthwise along the roof, or if the strips should be applied between the sheets, in including a degree of movement at either or both recommended strip lengths are exceeded, an The location is subject to some extreme ends. In the case of copper sheeting, a double lock order to avoid the rise of water by capillarity. Roofs and facades are subject to great temperature expansion joint must be placed between these SLIDING CLIPS weather, sun and snow, large temperature variations, which in turn give rise to stresses and welt is normally used across the width of the sheet, points. The fixed zone and expansion joint must be oscillations, solar radiation and strong storms. Snow on the roof can to load concentrations movements in the material. Primarily the roof, but irrespective of the slope. Lateral movements are positioned in the same place along the roof. which have to be taken into consideration when also the facade, has to be designed with a view absorbed by the basic spacing (about 3-5 mm) designing the load bearing structure. to the fact that temperature variations may occur which must exist between the standing seams. between the external surface and the underlying When it is necessary to use nails, installers must If the roof is to provide effective protection against structures. rain and snow, it is also important for the roof enlarge the hole on the sheet, in order to allow the thermal movements. PLAY IN THE drainage system, including gutters and piping, to SEAM TO ALLOW be designed and dimensioned correctly. In addition, FOR LATERAL the thermal insulation of the eaves and the roof and EXPANSION the ventilation systems must be carefully installed in order to prevent all kinds of ice formation.

40 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 41 INTERRELATIONS WITH BUILDING PHYSICS

GENERAL CONSIDERATIONS

When considering building physics related to metal If the partial pressure of water vapour remains PRELIMINARY DRAWING VENTILATED STRUCTURES VENTILATION PATH AND HEIGHT (SLOPE) sheet covered structures the most important below the maximum possible partial pressure OF A VENTILATED ROOF factors are heat transfer and vapour diffusion (dependent on temperature) throughout the whole In case of this solution the outside shell of metal Ideally, the best thermal current occurs with the through the building components that form the building structure condensation does not occur. As cladding is separated from the insulating and stack effect where the relationship of height and roof or the wall. Proper insulation and vapour a simple rule building is free of condensation, if: load bearing construction by a ventilating air gap distance is most favourable. As the slope becomes control are important for low energy, healthy and connected to outside air by inlets and outlets. This flatter, this relationship becomes more and more comfortable buildings. • The thermal insulation of construction layers ventilated air gap works with natural ventilating unfavourable. The stack effect no longer occurs increases from inside to outside: thermal effect; thus its effectiveness is dependent on in roofs pitched below 10°, so in case of such The roof can be heat insulated in different forms, transmittance (U value) becomes progressively following key factors: roofs ventilation must go crosswise, utilising wind e.g. with the traditionally used insulating layers smaller from inside to out. pressure. placed between and/or under the rafters or with • The water vapour diffusion resistance of the heat insulating panels designed specifically for construction layers decreases from inside to LAYERS OF ROOF – LOCATION AND FORM OF VENTILATION OUTLET sheet metal roofing, which at the same time serve out. VENTILATED STRUCTURE OPENINGS as the substrate of cladding. When considering a metal clad building, the first Inlets must be located at the lowest and outlets at The partial pressure of water vapour is dependent impulse is that this principle is reversed: the the highest point and must be adequately sized. on room temperature and relative humidity. If metal layer on the outside has the best thermal there is a temperature difference between in- and conductivity and the highest water vapour diffusion LENGTH OF THE VENTILATION AREA outdoors, a difference in pressure arises and resistance. There are two basic ways to solve this different potentials tend to seek equilibrium in problem: ventilated structures and non-ventilated COPPER CLADDING Generally, in ventilation spaces greater than 15m the direction of the pressure drop – the moisture structures. SEPARATION COURSE long the air current will come to a standstill. If BOARDING diffusion starts from inside out. AIR-GAP ventilation path length is longer it must be divided HEAT-INSULATION into shorter sections. INTERNAL COVERING POSSIBLE LAYER SYSTEM VENTILATION LAYER GUIDES

A narrowing of the layer, obstructions, interruptions and direction changes in the ventilation layer could cause the air current to stall, which would lead to moisture build up.

42 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 43 PRELIMINARY DRAWING OF NON-VENTILATED STRUCTURES LAYERS OF ROOF – EVALUATION A NON-VENTILATED ROOF NON-VENTILATED Copper has been installed on non-ventilated roofs STRUCTURE In conclusion it is clear that in individual cases a for many years for design purposes or under decision must be made depending on the building conditions that do not allow ventilation (e.g. large, requirements as to which kind of structure should low-pitched roofs). When properly constructed, the be used – either ventilated or non-ventilated. non-ventilated structures offer many advantages COPPER CLADDING for sophisticated roof geometry, well insulated SEPARATION COURSE In summary, let us suggest the usage of ventilated buildings in modern architecture. HEAT-INSULATION roofing systems in cases of simple roofs unbroken (PRESSURE RESISTANT) by superstructures and in cases of great slope The efficiency of non-ventilated metal cladding is VAPOUR BARRIER BOARDING angle, while the usage of non-ventilated roofing essentially dependent on the following key factors: systems is better in cases of more complex forms.

• Installation of an effective vapour barrier (sd ≥ 100m) that eliminates the diffusion of vapour into the roof structure. • Choice of metal for the cladding which can withstand small amounts of moisture in the roof structure without corroding. Copper is especially well suited because it does not suffer from underside corrosion. • If an underlay beneath the copper sheeting COPPER CLADDING is used It must be a breathable membrane SEPARATION COURSE otherwise condensation could form underside HEAT-INSULATION of the underlay. VAPOUR BARRIER • Carefully avoid possible damage of the vapour PROFILED SHEET METAL barrier layer during or after installation. It may Royal Academy of Music, London, UK cause the penetration of moisture into the Architect: Ian Ritchie Architects structures. Photo © Adam Scott

The location is subject to some extreme weather, sun and snow, large temperature oscillations, solar radiation and strong storms.

POSSIBLE LAYER SYSTEM

44 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 45 INTERIOR DESIGN

Copper Besides its popularity in architecture as a Architecture thoroughly modern material for roofing, facades Forum and other external architectural elements, copper INTERIOR SUPPLEMENT IN COPPER EUROPEAN forms part of the designer’s palette for interior ARCHITECTURE FORUM MAGAZINE COPPER IN ARCHITECTURE AWARDS items such as , handrails and contact surfaces (where its hygienic characteristics are The Copper Architecture Forum design A biennial showcase for the very best of also important), corner mouldings and detailing (to supplements issued under the title Copper European copper architecture. All entries provide continuity throughout an entire building), Inside are celebrating the diversity of and winners are detailed on Copper Concept. and feature elements like fireplaces and light applications of copper and its alloys inside Enter the next Awards! copperconcept.org/ fittings. buildings. Order your free printed copy or en/awards read them online attached to issue 39 and 43: Copper and its alloys are ideal for interior design copperconcept.org/en/copper-forum or scan Read the latest Winners’ Brochure online: instead of, or in combination with conventional QR code. copperconcept.org/en/publications/ materials. The surface of copper can be varnished european-copper-architecture-awards-18- or waxed to preserve its distinctive colour and shine winners-brochure indoors.

Nowadays, there is also a growing trend for wider, innovative uses in interior design inspired by copper as wall, ceiling and floor coverings or copper-clad sculptural staircases. Additionally, copper mesh and perforated copper sheets can be used internally as partitions, screens and other interior elements. Three-dimensional shapes also provides endless opportunities in interior design and decoration. Red Bull studio, , Germany Architect: Optimist Design Photo © Jan Bitter for Optimist Design

A visual rhythm has been created by forming the shape of the copper strips into an undulating sequence to represent the natural flow of sound and music.

Awards 2017 winner Maersk Building, Copenhagen, Denmark Architect: C.F. Møller - Photo © Adam Mørk

46 COPPER IN ARCHITECTURE 2019 COPPERCONCEPT.ORG 47 48 COPPER IN ARCHITECTURE 2019