VMZINC explores the history and certification of zinc roofing and cladding.

The first zinc roof was installed on St Bartholomew’s Church in Liege, Belgium, in 1809. Over the coming century Baron Haussmann made zinc the roofing material of Paris, and the metal’s use extended to the UK, USA, Japan and even Notre Dame Cathedral in Saigon (now Ho Chi Minh City), Vietnam, as well as many other parts of the world.

Since the 13th century Les Compagnons du Devoir, an organisation which has given a technical education to many trades in the form of travelling apprenticeships, has continued, and indeed expanded to many more trades and countries. In the 19th century the skill of the zinc roofer came under the wing of the organisation, thus further improving the skill and knowledge of the zinc roofer.

While it is not entirely clear who first extracted a pure form of zinc, the zinc used on the church in Liege in 1809 came from a process developed by a chemist named Dony. Vieille Montagne employed essentially the same process, and supplied the zinc used in Haussmann’s Paris. Up until the 1920’s the industrial processes and techniques used to install zinc roofs did not dramatically change.

In 1922, the VMZINC factory in Viviez, France, started to extract zinc through a process of electrolysis, thus creating a much purer material, which was the fore runner of Special High Grade Zinc EN BS 1179. This zinc was later combined with small amounts of copper and titanium to create the modern alloy, EN BS 988. The technology was then combined with a further advance in metal refining: continuous rolling. The combination of these two technologies gives us modern coils of zinc that can be laid on a roof in lengths up to 13-metres long. The Viviez plant still produces the majority of VMZINC used outside the traditional markets of France and Germany, and is the world leader in pre-weathering zinc, which now comprises of 10 standard finishes.

While EN BS 501 and Code of Practice 143-5 do give valid information on fully supported, vented zinc roofs and walls, they do not go into all of the details required in order to design and install modern zinc roofs and walls. It is for this reason that VMZINC has produced a number of documents over the last eight years aimed at assisting both architects and contractors. These include, but are not limited to:

• Standing Seam and other roof systems, gutter and downpipe systems
• fully supported and rainscreen facade systems
• Standing seam installation guide

The guides do also refer back to a number of third party accreditations.

Since 2012, VMZINC has had BBA certifications for two non-vented warm roofs: the Compact roof designed for high humidity buildings, such as swimming pools, and the Structural roof. Warm roof build ups greatly reduce thermal bridging and make it far easier to install an effective vapour barrier, which also acts as an air barrier thus improving thermal performance. Equally important are durability, low maintenance, and ease of recyclability at the end of life, which is sometimes 100 years later. This information is outlined in Environmental Product Declaration EN 15804.

VMZINC cladding and roofing on a contemporary residential development

Another question that is rightly asked almost immediately, is combustibility. As zinc itself is a metal, it is non-combustible A1, following EN13501-1. However, it is equally important that the whole system is compliant, and for example, both vented cold roofs and non-vented warm zinc roofs have no flame penetration or flame spread following testing covered by BS 476-3 and CEN/TS 1187 Brooft4.

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. However, for facades where only A1/A2 materials following EN13501-1 are required, the timber can be replaced with a 0.7mm thick galvanised steel deck. It is also import that appropriate fire barriers are used in the cavities and that an A1/A2 insulation is also used.

Finally, it is now possible for VMZINC to offer a 50-year material warranty when the above requirements are followed by both designer and installer. It should be noted that the warranty is only available to VMZINC@WORK partner installers. These installers not only have a track record in the successful installation of VMZINC but have also followed training sessions that are designed to inform them of all the requirements that must be followed.

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If you would like any further information including samples or an online RIBA accredited CPD please call 0203 445 5640, email, or visit the website.