Jonathan Lowy of VMZinc says the history of zinc specification aligns with its future
When zinc was first used as a roofing material at the beginning of the 19th century many of the reasons for its choice all that time ago are still relevant today; availability of the metal, the technical advantages of the roofing systems and the attractive aesthetic of the material.
Zinc was first extracted and rolled in Liege, Belgium in 1809, and while this factory has long since closed, zinc is still refined and rolled in western Europe making it an easily available material. In 2024 the majority of zinc used for roofs and facades in the UK and Ireland was produced in France and thus has a relatively low carbon footprint due to the makeup of France’s electricity supply. An added attraction is the durability and recyclability of zinc. The BRE gives zinc an expected life of 100 years with over 98% recycling of the zinc roof panels at the end of this long life. Furthermore the maintenance of a zinc roof is little more than clearing out the gutters annually. Environmental Product Declarations for zinc in accordance with EN 15804 offer a more in depth view of the metal’s performance.
In the early days of zinc roofing the batten cap system was used, not dissimilar to a lead roll but in recent decades the standing seam system has become more popular with its ability to cover complex shapes and surfaces with slopes as little as 3° all the way to walls and even soffits. This makes it a material and approach that is truly for the whole building envelope. For facades the choice of system is vast and includes traditional fully supported panels such as standing seam and flat lock panels as well as a wide range of rainscreen cassette systems.
Zinc should not be confused with galvanised steel, which is simply steel protected with a very thin layer of zinc or painted metals where the paint either protects the metal beneath and/or enhances the substrate’s aesthetics. Metals such as zinc and indeed copper are used both for their inherent beauty and durability as solid non painted metals. It is possible however to chemically modify the surface of zinc thus changing the metal’s aesthetics and pre-weathered zinc has now been available since 1978. This form of zinc remains solid and is non-coated.
A further advantage of zinc roofing and cladding is the relative lightweight of this type of building envelope. The majority of zinc roofs and walls weigh less than 10 kg/m2 which is far less than tiles, stone or indeed lead, this not only reduces the environmental footprint but can also reduce the size of the substructure beneath the zinc.
If you watched the 2024 Paris Olympics you may have admired how many Parisian monuments were used as backdrops for many of the sporting venues. This almost automatically means that zinc roofs and ornaments were also part of these backdrops, whether it be the quays by the Seine and grand boulevards of Paris or the many zinc ornaments, for example those found on the Grand Palais. Whilst zinc does still have somewhat of a heritage image in France and other parts of continental Europe it has far more of a contemporary image amongst UK architects.
One such example is Sheppard Robson’s transformation of 68-86 Farringdon Road in London from a car park to a mixed use scheme, with an exciting streetscape which includes the use of pre-weathered QUARTZ-ZINC flat lock wall panels. Another site that has undergone a significant change is the Rosebank distillery in Falkirk. Michael Laird architects have beautifully blended existing structures with new ones clad in dark grey pre-weathered ANTHRA-ZINC panels. Last but not least and in a way going back to how zinc is used in the French capital, Simpson Brown architects designed a new visitor centre for Lincoln Cathedral which is designated as a Grade 1 listed site thus showing how in this case, QUARTZ-ZINC roofs and walls can be used in such a sensitive setting.
In addition to BRE Environmental Product Declarations and extensive historic examples showing how durable and recyclable and therefore sustainable zinc is, third party accreditation such BBA system certificates and Brooft4 fire tests are also available. Additionally, architects can tap into a wide range of design services whether it be CAD drawings, BIM models or detailed information on substrates. Correct installation is vital and lists of recognised contractors who regularly install zinc roofs and walls in the many systems that are now available can also be issued. All of these contractors can also install the sometimes forgotten zinc rainwater systems.
Jonathan Lowy is operational marketing manager at VMZinc