Introduction

Zinc is an excellent roofing and cladding material which will give long and almost maintenance-free service if installed properly.  Proper installation means not only the correct fixing of the zinc itself, but also the correct design and installation of the supporting structure.

In traditional roofing and cladding this structure provides a continuous support for the zinc, whereas in engineered façades, metal railing and point fixing systems are employed.  The information provided in this section can be used as a guide to the basics of zinc roof construction.  Any relevant national norms and codes of practice in your country or region should be consulted and adhered to.

Traditional systems are fully supported metal coverings that employ tried and tested hard metal seaming techniques which have been used for centuries.  The double lock standing seam, batten roll, angle seam and flat lock cladding fall into this category.  The complete elZinc® range of finishes can be installed using these systems.  They have several characteristics in common.

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Common characteristics:

Light, timeless, artisan appearance.

These systems are installed by specialist hard metal roofing contractors giving a hand crafted, made-to-measure feel.  The subtle quilting that can become apparent naturally under different light conditions introduces a bit of visual ‘vibration’ and ‘energy’ to the building.

Adaptable and architecturally flexible.

Making use of the malleability of elZinc®, the panels can be curved, tapered, formed and folded to conform to almost any geometric design.  Intelligent use of the joints can convey interesting effects.

Proven durability.

Zinc standing seam roofs have been known to last for well over half a century, and traditional zinc cladding lasts even longer.

Economical.

The thin gauge of elZinc® used coupled with modern bending and profiling technology keeps costs more affordable.

Installation.

They should be installed by experienced fully supported metal roofing specialists.   Contact elZinc® for a list of reputable firms for your project.

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Technically, they share the following features :

Use of thin gauge zinc.

Zinc between 0.65 and 0.8mm is normally used since these systems require ease of hand forming on site to execute the joints and details.  In countries new to this type of cladding, there is a temptation on occasion to use heavier gauge material to eliminate oil canning, but this should only be done after consultation – many traditional joint details cannot be executed in material thicker than 0,8mm.

 

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Folded and welted joints to connect panels.

These joints create protruding seams or small steps between the panels.  They are either simply interconnected or welted together on site.  The seams are not watertight, and their weathertightness varys, so each type of joint has its own pitch-related limits. Optically, these joints interact with the light generating intesting effects which can influence our perception of the façade at different times of the day and year.

Fully supporting substrate.

Due to the thin gauge of the zinc used, they require a fully supporting substrate (or partially supporting substrate for façades).  This can either be of a vented or unventilated design, and helps reduce rain drumming especially if combined with structural underlays.

Indirect fixing using stainless steel clips.

These fixings are hidden by being overlapped by the next panel in the sequential installation of the covering.  They hold the cladding down to the substrate whilst ensuring it can expand and contract freely as it warms up or cools down.

Governed by national norms and codes of practice.

These systems should be installed according to national standards and codes of practice.  Independent system certification should not be required since they employ tried and tested techniques and methods.

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Panel widths and clip centres in traditional systems

 The following table can be used to determine the bay widths, thicknesses, and also to specify the number of fixings per m2 for each of these systems.
System dimensioningFixing requirement – number of clips per m2/clip centres in cms related to building height
8 m < H <= 20 m2 0 a 100 m
Thick.Bay widthCentreEdgeCornerCentreEdgeCornerCentreEdgeCorner
0.74303.9/483.9/486.4/293.9/485.5/349.6/203.9/487.7/2512.8/15
0.75303.9/483.9/486.4/293.9/485.5/349.6/203.9/487.7/2512.8/15
0.76003.9/433.9/436.4/263.9/435.5/309.6/173.9/438.5/2012.8/13
0.76304/404/406.4/254/405.4/2910/16

*Notes:  Assumes a nominal clip pull out load of 560N.

Valid for non-exposed locations.

Various factors affect wind uplift  and advice should be sought from elZinc® when determining tray widths for projects in exposed locations.  This is not only to ensure that the cladding does not suffer during storms, it is also to avoid fluttering of the trays during periods of continuously windy weather.

Bay widths may be narrowed to the next standard width in order to reduce quilting in the sheets if a flatter appearance to the cladding is required, especially for wall cladding or steeply pitched roofs.

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