Simon Walker from SIG Zinc & Copper shares his knowledge and insight into the benefits and approach to using copper in builds
For designers and architects, selecting the most appropriate solution for cladding or roofing involves finding a balance between aesthetics, sustainability, and durability.
There is no definitively right answer, and with a plethora of options available, designers have a lot of decisions to make. Even when a metal solution seems obvious with its long life, there is still the choice between aluminium, steel, zinc, and copper. The performance characteristics of each material, as well as their very different aesthetics, will all influence the choice.
Copper is known to provide an ideal solution for designers looking for a cladding which is highly malleable – key for curved or irregular shapes – while still being long-lasting.
This malleability makes the material popular with designers looking to work with the same metal finish for gutters, downpipes, and flashings. It’s an established practice to use copper for cappings, ridges, flashings and full rainwater systems because of the metal’s comparative softness and ease to work with.
Being a lightweight material makes it easy for contractors to work with too. The traditional 0.7 mm size used for standing seam roofing, angle seam cladding and shingles or flat lock weighs only 6.3 kg/m2.
Conversely the lightweight nature of the metal can result in natural undulations, particularly on flatter sheets, which some designers or clients might find unappealing but for others is part of the charm of the material.
Copper has a unique ageing process that causes the material to change its appearance radically over time. Starting from a bright traditional copper colour, the hues change to brown, dark brown, and eventually end in Verdigris.
For designers who want certainty on the appearance of the material over time, pre-weathered copper is widely available to give a specific colour or weathering stage of the material. Also available are different alloy compositions such as brass and bronze with their own ageing characteristics.
Each of these options give their own distinct colouration, together with different levels of strength or corrosion resistance and can improve forming or joining properties. Different finishes including gold or tin are available for designers seeking the perfect finish.
Considerations for design and installation
Different materials will also offer a range of options for specific installation techniques with copper being an excellent choice for traditional seam roofing, angled seam facades, shingles, and flat-lock tiles as well as for prefabricated and engineered solutions.
Ventilated facades allow for the circulation of air between the cladding and the substrate to regulate temperature as well as reducing water damage, mould, and structural damage to the building. For copper, air flow and ventilation are not essential for maximising the lifespan of the material and therefore can be used in the design of both ventilated or non-ventilated roof and wall systems.
Regarding fire specification and protection, it is always recommended to engage with a distributor to assess systems that can offer advice and system warranties for applications when installed correctly. For context, copper sheets and strips achieve Reaction to Fire Classification A1 according to EN 13501-1. This means the product is non-combustible/no contribution to fire.
Maintaining copper on facades and roofs
Copper is generally a maintenance free material as rainfall is typically sufficient to clean the surface area in most situations. Typical maintenance best practice measures should still take place, such as visual inspections to ensure no obvious signs of damage or build ups in gutters. In most instances, regular cleaning or a dedicated maintenance regime isn’t required.
If specified correctly, designers and building owners can expect the copper cladding or roof to last for many decades. The exact duration of the lifespan varies depending on specification and installation however copper can be relied upon to be an enduring metal to work with.
Copper has a long life span and when reaching the end of the life cycle, copper can be recycled without loss of performance. This is, in part, because copper can be installed in roofing with no underside corrosion issues which can affect other non-ferrous materials.
Typically, if the copper is uncontaminated, it can be melted down and reformed ready for use. For copper which does contain other impurities, it’s possible to adjust composition by introducing other metals, or by re-refining it to make an acceptable specification, thus keeping the copper in use.
With all its aesthetic and practical advantages it may not be surprising that copper is likely to be an expensive option in comparison with other products. Due to supply and demand, we’ve seen market price increases of up to 20% which does limit its usage. Most affected will be smaller, domestic projects or on specialist finishes where minimum order quantities can affect buying power.
On larger commercial projects, we advise early engagement with the supply chain to ensure availability. On average, expect 12-16 weeks for manufacturing however this can be accounted for when factored into the project programme.
For designers and architects, copper represents an ideal solution for a building material combining a long-lasting life span with a unique and desirable aesthetic. The ease of installation and minimal maintenance required can be seen to offset the price bracket and when factored into plans, lead times are more than workable.
Simon Walker is category manager for hard metals at SIG Zinc & Copper