Our technical webinar hosted with VMZINC explored how to correctly specify and install zinc facades and roofs.

Zinc roofing and cladding has long been favoured for its aesthetic appeal, durability and sustainability. Merely how can architects ensure they are following all-time do when it comes to specifying and installing dissimilar zinc systems? What pattern aspects should they pay particular attention to? And how should they approach problems relating to procurement and budget? These questions and more than were explored in this Architecture Today webinar, in partnership with VMZINC.

In association with

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Baron Haussmann chose zinc to transform Paris in the 19th century

History
From a historical perspective, zinc is perhaps most closely associated with Baron Haussmann's urban renewal programme in Paris (1853-70). Much of this architecture required roofs with a slope of three degrees, which is still the minimum angle for zinc roofs (equally built). The material was as well widely used in the UK during this period, although mainly for civic buildings.

A good example is the Picton Reading Room dome in Liverpool (1879), which was refurbished later more than 130 years of service. While most of the original design was kept, current regulations meant that panel widths had to be reduced and standing seams were incorporated between the batten caps. Current corrosion rates are less than 2 microns per year – a sheet of zinc is at least 700microns thick.

Substrates
Correctly designed substrates are central to successful zinc roofing projects. A cold vented roof must have an air inlet at the base and ridge (minimum 10mm open), and a minimum 50mm deep continuous cavity between the back of the substrate and the insulation. When a vented plywood back up deck is used, VMZINC PLUS with a 60-micron underside coating should be specified to protect the behind of the zinc from acidic glues that may be present in the timber.

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Cold roof build up – vented plywood

A non-vented warm zinc roof must have a fully supported, unbroken, cocky-sealing Aludex Max vapour barrier, with a continuous layer of rigid insulation above (reducing thermal bridges), followed by a VMZINC breather membrane, and so a VMZINC PLUS roofing.

The Structural roof has a BBA certificate and can be used with both PIR and mineral lath insulation. Begetting plates and pegs greatly reduce thermal bridges thus further enhancing the system. The fully supported Aludex Max vapour bulwark which increases air tightness can be seen beneath the insulation and the VMZINC breather membrane higher up.

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Continuing seam roofs
VMZINC continuing seam systems are highly flexible and can cover nigh all roof forms. Both warm and cold roofs have no fire penetration or flame spread following BROOF(t4) tests. Specifiers should remember that the correct flashing must be used for the right detail, and eave details need to be adapt thermal movement while remaining weathertight.

Zinc aesthetics
Zinc can be chemically treated to requite a range of different aesthetics, but always with a hint of greyness. Natural zinc is shiny just forms a patina when it reacts initially with water and then with carbon dioxide. After 3-x years an even middle grey patina is formed, but it takes time for this to become compatible.

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ANTHRA-ZINC roof at the Bourne Estate in London

Pre-weathered QUARTZ-ZINC imitates naturally weathered zinc through a phosphatation procedure and changes very piddling over the lifetime of the roof or facade. Pre-weathered ANTHRA-ZINC'southward dark greyness appearance has proved popular for both wall cladding and covering.

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PIGMENTO Brown covering and cladding on a private house in Berkshire

VMZINC'southward `off the shelf` PIGMENTO range comprises Blue, Cherry-red, Dark-green, Dark-brown, Greyness, Storm Grey, and Charcoal Blue colours. The surface tone is created by adding mineral pigments to a durable pre-weathering zinc, which is then sealed with a protective coating. Azengar, which is an engraved zinc, combines both mechanical and chemical treatments. It can be used for covering and cladding. All finishes tin be used for all systems, including continuing seam.

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Stand seam facades
Warm wall structure is possible, but well-nigh clients and organisations such as NHBC prefer vented cold wall construction. Information technology should exist noted that zinc is not-combustible following EN13501-i. Natural Zinc, Azengar, QUARTZ-ZINC and ANTHRA-ZINC are all therefore A1. Coated products, such as PIGMENTO and VMZ PLUS, are A2 classified, just however permit the zinc to be used on all buildings over 18 metres high. For projects where EN 13501 A1/A2 materials are required, a 0.7mm thick galvanised steel support deck can be used in place of a timber one.

Standing seam panels will never exist completely flat just using 0.8mm thick zinc and 430mm wide single lock panels volition help with this. For ease of installation, it is recommended that panels measure no more than than four metres in length.

ANTHRA-ZINC and QUARTZ-ZINC were used to renovate Parsons Belfry in Newcastle

Zinc flexibility
Almost immediately after zinc was first used on roofs in the 19th century, it began to be employed as a material for roof ornaments ­– and still is. Information technology is also highly malleable, as evidenced by the zinc dormer windows and balustrades that form part of the Poundbury development in Dorset. Zinc'south lightweight and flexible backdrop mean that it is ideally suited to renovation and retrofit projects.

Buildings.

Flat lock cladding at Kingsland wharf, London, designed by JCMT Architects

Facade options and gutters
The choice of systems for zinc roofs is fairly straightforward, only for facades the options are far greater and include flat lock panels, bespoke shingles, and diamond shingles. The latter can exist used for roofing on slopes above 30 degrees. Flat lock panels come up in many shapes and sizes, but should non be specified larger than 3000x600mm.

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Hidden box gutters should have falls of i:100

Hidden box gutters are common features on zinc roofs and should have falls of i:100, overflows and expansion joints. Hanging gutters tin also be used and should exist fitted with a minimum autumn of i:200. A range of half round gutters in QUARTZ-ZINC and ANTHRA-ZINC with subconscious brackets are stocked in the Great britain. Rectangular and OGEE gutters are also available.

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Rainscreen facades
The Mozaik panel system is a good choice for zinc facade panels measuring upwardly to 600mm wide.  Panel depth can be altered to forty, threescore, 80 and 100mm, giving the possibility of a more textured facade. The reveal joints are e'er 15mm wide.

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Sine moving ridge cladding panels

Horizontal send lap panels with a 200mm coverage width can be installed on metal or timber cladding rail. The panels themselves can accept a depth of either 13mm or 20mm.

Sine wave or corrugated panels are available in all finishes and fasteners and can be installed both horizontally and vertically. The standard wave size is 18x76mm. The panels tin can exist perforated and/or curved.

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Interlocking panel cladding

Interlocking panels are probably the mostly commonly used zinc rainscreen system. They have a depth of 25mm, and the nearly mutual center-to-centre distance is 300mm, including a 10mm or 20mm reveal joint. Interlocking panels can be installed horizontally or vertically, are tested to the CWCT protocol, and will e'er sit flatter than a standing seam facade.

Budget and procurement
The toll of a zinc roof or wall will depend on the organisation used, every bit well as the size and location of the project. Most zinc systems can be supplied and fitted for £100-£200/m². Most products are stocked by Uk or Republic of ireland-based distributors making zinc rapidly available.

It is critical that continuing seam roofing and cladding is installed by a competent 'difficult metal contractor'. VMZINC@WORK partners accept a track record of successfully installing zinc roofs and walls, they also know and sympathize our recommendations following training. Wellness and safe regulations must exist followed, with all risks assessed, PPE used, correct lifting and handling employed, and working at height applications carefully accessed.

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Contact Details
VMZINC can supply literature and samples, as well equally CAD drawings and specifications. Nosotros're always happy to talk over specific projects and can supply lists of appropriate contractors. For more than information, please call 0203 445 5640, electronic mail, or visit the VMZINC website.