Zinc’s lasting sustainable appeal

Jonathan Lowy of VMZinc looks at the lasting appeal of zinc as a sustainable solution for the building envelope, as shown on projects from the 19th century to the present day

The Parisienne rooftops adorning Hausmann’s famous 19th century buildings helped to define a cityscape that attracts millions of tourists every year. What these buildings have in common is their relative uniformity of materials and designs, which in the case of the roofing, is the use of rolled zinc. Hausmann’s Paris rebuilding programme was the catalyst for the widespread application of zinc and more than 150 years later, this non-toxic, easy to recycle metal is used extensively for standing seam roofs, in particular, in all kinds of contemporary and traditional architecture. As a material that was originally favoured for its durability, workability and aesthetics, it is the additional sustainability dimension to zinc which today offers significant additional appeal in an era when clients and developers are increasingly seeking the most sustainable material choices for their buildings. Zinc’s appeal for roofing and cladding is driven by its material characteristics – ‘self-protecting’ through its own patina, which develops over time through exposure to the air and water, with long lasting aesthetic appeal. It is also maintenance-free, requiring only rainwater to retain its appearance – no chemicals or special treatments.

Sustainable & safe

As an easy-to-recycle product providing an in-situ lifespan of up to 100 years, zinc’s environmental credentials compare very favourably. It is estimated that over 90 per cent of post-use zinc is collected and recycled to manufacture new products, helping to minimise resource use. Further sustainability credibility comes through the Environmental Product Declarations (EPDs) available for zinc products provided by the BRE and conforming to EN15804, which further demonstrates that the life cycle, manufacture and processing of zinc products have minimal impact on the environment. The fact that zinc cladding and roofing requires no maintenance during its long service life also helps to minimise its carbon footprint. This ‘fit and forget’ quality is valid for any application where rainwater is present, with the exception of soffits on some buildings located in coastal areas. In addition, metals are by definition non-combustible, which makes them a fire safe choice for the building envelope, providing that the surrounding structure, insulation and attachment method matches its performance characteristics, and zinc is no exception. Zinc roofing and cladding products are available as either A1 or A2 classified for non-combustibility, without any special requirements. Zinc cladding or roofing can be fixed to a galvanised steel deck, with the correct insulation specified – basic steps that will maintain fire performance should the worst happen.

Unrestrained geometric freedom

While zinc is widely used for standing seam roofs, this is only part of its story in architecture. This versatile material has been applied to numerous other external envelope elements since it first found its niche in 1830s Paris. It was around that time that production ramped up with new factories capable of meeting a growing roofing demand and innovation thrived with the development of a broader range of zinc products. Today these include cladding, rainwater systems, and interior and ornamental applications. As a malleable material that lends itself to different forms with ease, zinc’s ability to be shaped gives it enormous potential for delivering striking, contemporary architecture. Whether it is a curved facade or an angular structure with multiple facets, a combination of zinc cladding and roofing systems, plus ornamental elements, enables consistency in form, function and performance. Aesthetics and creativity can flourish through the range of surface finishes developed over the past four decades, including engraved zinc. Delivering timeless architecture, however, requires flexibility, which is what makes zinc ideal for unrestrained facade aesthetics. The material can be made to bespoke requirements, through embossing and perforation, with project-specific finishes also an option. While pre-weathered zinc is used most widely, natural zinc is still used where a design calls for a more organic and uneven appearance before the patina forms. As well as more traditional roofing systems such as standing seam and batten cap, facades give designers more creative scope including rainscreen systems such as interlocking panels, with concealed fastening for clean sightlines and a neat finish. The refined and subtle finish of zinc on the external skin is part of a complete wall build up incorporating acoustic and thermal insulation to meet specific project values.

All round performer

Despite the changing architectural trends and constant innovation in building materials, zinc has stood the test of time and it is now a fundamental in contemporary architecture. From the elegance of central Paris to the edgy architecture of Melbourne, to projects in Texas and the Scottish Highlands, this versatile, sustainable material continues to play a key part in delivering outstanding buildings and enabling aesthetic creativity to flourish.

Jonathan Lowy is operational marketing manager at VMZinc