Over the last 50 years, the technology used to refine and roll zinc has changed considerably
to see the performance of zinc with regards to sustainability.A number of UK wall panel manufacturers have also carried out CWCT tests (Centre for Window and Cladding Technology) on zinc rainscreen panels, demonstrating a safety resistance of 3600 Pa.
Fire performance Post-Grenfell, fire performance has obviously been at the forefront of many designers’ minds. Zinc is classed as non-combustible following EN 13501-1. By adding backside coatings – which are often used on non-vented warm roofs – the material becomes A2 (following EN13501-1). Non vented warm roofs do fall outside the traditional code of practice documents. It is for this reason that such structural systems carry a BBA certificate as well as testing covering BS 476-3 and CEN/TS 1187 Brooft4 for no flame penetration or spread. Traditionally, many fully supported zinc
facade systems such as standing seam and flat lock panels relied on vented timber as a substrate and this can still be used on many buildings. For facades where only A1/A2 materials following EN13501-1 are required the timber can be replaced with a 0.7 mm thick galvanised steel deck. It is also important that the appropriate fire barriers are used in the cavities and an A1/A2 insulation.
Aesthetic considerations As far as aesthetics are concerned, the nature of the panels used are critical: small elements, horizontal/vertical panels or the standing seam panels, with the use of interlocking panels giving a higher level of flatness. Another important choice is the nature of the zinc used. Until 1978, the only option was mill finish, natural zinc. Over the last 40 years, the choice and availability of pre-patinated zinc has expanded and now includes colour and engraved options.
Jonathan Lowy is operational marketing manager of VMZinc
Photos © VMZinc
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