SIG Zinc & Copper detects metal renaissance

Growing numbers of architects are choosing metal for roofs and cladding not only because of its undoubted green credentials and lustrous good looks but also because the use of the material has evolved stylistically. By Simon Walker, category manager for SIG Zinc & Copper

Gone are the days when metal made an appearance only on barns, farm sheds and other rural buildings. Recent trends show it is migrating away from the countryside and bringing its distinctive aesthetic qualities back to the urban environment, reminding us in the process of metal’s long heritage, especially on roofs, as an architectural statement.

Beyond delivering a dramatic visual impact with zinc, copper and stainless steel, the materials are proving popular with architects for a whole raft of reasons, not least their versatility and the way they can convey the design ideas that inform an entire building.

Thanks to their natural patina formation, they offer a long lifespan. They are also largely maintenance-free and 100 per cent recyclable, so they can contribute to high BREEAM ratings.

Zinc has many of the characteristics architects love. It can be used on the entire building envelope and loves to follow curves and angles. Whether used on the roof or for cladding, it always looks splendid and its crisp lines accentuate shape and design features. There is also no need to rely on time to create a good patina on zinc; a range of finishes is now available, including pre-patinated, matt and textured, as well as colour options.

This increasingly popular metal – the 24th most abundant resource in the world’s crust at 75 parts per million in mass – is tough, seriously tough. Weatherproof, corrosion resistant and not degraded by ultra violet light, it can last up to 100 years without degradation, and there are many examples in Northern Europe that have exceeded that timeline.

The long life of zinc makes it a cost effective choice when considering whole life options. But zinc can also be cheaper. Currently, it compares well with alternative metals such as copper, lead and stainless steel.

Copper’s warm colouring lends any building a certain elegance, and there are many centuries-old green copper roofs still standing as testimony to its longevity. Its resistance to the elements is one of the reasons copper ranks among the most desirable of modern roofing materials. It is also much appreciated for its ease of formation, even over irregular structures and shapes, and for its compatibility with other materials. It is a material that adapts to many architectural styles.

As with zinc and copper, stainless steel scores well in the durability and low maintenance departments. It also offers truly dramatic visual impact. This is achieved not just through its own intrinsic and striking good looks as a material but because its use allows greater design freedom – it can span greater distances than other materials.

Hard metals offer the designer and specifier a wide palette of options. However, some issues need to be explored before they are specified. Firstly, initial costs are expensive but this can be offset by the longevity of the product and by eliminating waste by choosing a supplier who can offer bespoke quantities of materials. Secondly, there can be compatibility issues; this is why the technical guidance of an experienced supplier must be sought. And lastly there are limited design standards.

While metal roofing and cladding is certainly enjoying a renaissance, the wide range of market offers launched to meet demand for these in vogue materials has resulted in a certain level of confusion among specifiers. Much of this focuses on varying product quality, different detailing options and conflicting advice on finish and construction method from manufacturers.

The number one route to demystifying the specification of hard metals in architecture is choosing a supplier or manufacturer with comprehensive technical support. The supplier should be able to provide technical information, including bespoke details, NBS Specifications, 3D build-up and a warranty. Of course they will be able to offer advice on which products to use but, more importantly, they must also be able to advise when those products are not suitable for a particular project or application. A full, impartial design and supply service is the launch pad for success when specifying metal materials for any building design.