While the increasing specification of zinc owes much to its versatility, comments from architects invariably confirm that factors other than design scope have influenced their choice. The end result is visually distinctive, and diverse projects are providing an effective "shop window" for what can be achieved.
In terms of aesthetics, zinc cladding systems can be used with virtually any building material - timber, natural stone, brick, concrete and structural glass to name but a few. Standing seam, interlocking (with recessed joints) and overlapping vertical and horizontal panel systems are available in pre-weathered colours to provide a fully developed, stable natural patination.
Those such as VM ZINC's Anthra-Zinc® and Quartz-Zinc® continue to age normally and, being non-ferrous, are self-protecting, corrosion resistant and effectively maintenance-free. The subdued shades of the red, green and blue Pigmento® range provide subtle tonal variation that just isn't available with other metals.
To guarantee long-term colour integrity, mineral pigments rather than chromium-based additives are used. Architects' comments on their reasons for choosing zinc make interesting reading. David Pierce, of Urban Salon, said: "We recently specified zinc for the first time for the design of Falmouth School's new design and technology block. We wanted the building to appear as a series of folded planes, with walls and roof clad in the same material.
"It was crucial that the product we specified worked as well on both surfaces, and using zinc meant that we didn't need to compromise. We were seduced by the Anthra-Zinc finish; the contrast between the black and grey zinc and the exposed timber is very powerful."
For the £4.5 million refurbishment and extension of the Pier Arts Centre in Stromness, Reiach and Hall specified VMZINC Plus®, again in Anthra-Zinc. Architect David Anderson said: "The product was chosen for its known performance in a typically harsh marine environment. The new building extends and links the existing arts centre buildings and comprises a simple two-and-a-half-storey pitched roof structure, recalling the various seafront warehouses that pepper Stromness foreshore.
"In order to signify the public use of the building, we chose to abstract its form by cladding most of it in one material - zinc. This provided continuity of material for the south-facing roof, rear wall and gable and fulfilled our desire to clad the ribs to the fully glazed north-facing roof and wall. The Anthra-Zinc colour is muted and responds well to thin, low northern light, revealing subtle changes in plane and texture, particularly when viewed from a distance."
From a technical perspective, the ability to work and shape zinc makes it an ideal cladding material. Being 0.8mm thick and installed directly onto plywood, the VMZINC Plus standing seam system is extremely malleable and able to follow very complex forms. An 18mm-thick plywood substrate is a basic requirement, but this can be in two sheets of 9mm or even three of 6mm. This not only allows the plywood to flow and curve smoothly at tight radiuses, but also gives the zinc a completely rigid support that limits any potential for impact damage at low level.
Systems in aluminium normally require coating and where welding is required the coating has to be removed and repainted. In contrast, zinc's patina has to be removed only for soldering, but it re-forms naturally. By virtue of its compatibility with so many materials, Zinc is less visually intrusive on the skyline and can co-exist in many environments. There can perhaps be no better endorsement of its value than the introduction of aluminium systems with a (very thin) zinc pre-weathered coating.