The increasing emphasis of design life value when specifying for commercial projects has prompted the development of metal façade and roofing systems of greater durability and lower maintenance. Despite its technical advantages, however, use of stainless steel has been held back by the perception that it is expensive.

Comparison of metal prices per tonne would certainly preclude selection for most projects but its enhanced strength means that thinner gauges present no compromise in strength. When comparing cost per square metre things therefore look very different.

To put this into perspective, a typical minimum façade thickness for aluminium and copper is 1mm compared to zinc at 0.8mm and stainless steel at just 0.5mm. Though roofing systems can be slightly thinner, a simple 300m² area requiring around 1 tonne of stainless steel will still weigh 1.5 tonnes or more in zinc or copper (and more than 10 tonnes in lead)! For large projects such as the new £45m, 80,000 sq. ft. Marks and Spencer and Wagamama restaurant on Glasgow Fort retail park, UGINOX® 0.6mm stainless steel shingles specified by architects Cooper Cromar saved around 18 tonnes in façade weight. In terms of aesthetics, the highly smooth, polished 2K finish provides maximum resistance to accumulation of contaminants and was described by the architect as ‘an elegant stainless steel-clad box’. It undeniably forms a distinctive feature when approached from the motorway.

Among the many factors influencing use of metals in construction, the need for greater sustainability has been an undeniable driver of change. Stainless steel has been associated predominantly with highly polished finishes but the choice of visual effects now available includes linen, lozenge and chequer patterns in a palette of different colours and textures. Traditional bead and sand blasted options all show a level of detail which can only be achieved through use of advanced rolling techniques.

The desire to use colour and texture has never gone away and the growing use of stainless steel owes much to the introduction of these contemporary colours and finishes, the affordability of which is gradually becoming more widely appreciated. Where once there might have been little or no consideration of aesthetics there is now greater scope than ever before to put a personal stamp on design without adversely affecting performance.

The variety of colours and finishes in stainless steel is perhaps best illustrated by English Heritage’s endorsement of a material which, through natural patination, takes on the appearance of aged lead sheet. UGINOX® Patina provides scope for use as a standing seam or roll batten finish and has a low coefficient of expansion which enables tray lengths to be up to 20 metres. The thin gauge greatly reduces structural loading on centuries-old timbers, a 0.5mm system weighing 4kg/m². While clearly wanting to encourage lead’s continued use on historic buildings, it was considered pragmatic to approve stainless steel because of its appearance, long design life and affordability. Where lead theft continues to be a risk or lack of funds / insurance preclude its use, stainless steel offers the vital balance between retention of the visual aesthetic and long term performance. Unlike lead, it is not susceptible to cold working fatigue and can be soldered at low temperatures. Just as importantly, it can be used in harsh environments.

Such developments are a world away from the highly polished finishes with which many specifiers still associate the metal. Dramatic façades such as that on the John Lewis Store and Cineplex in Leicester undoubtedly take the eye by reflecting colour and changing light. A 34,000m² rain screen was commissioned in a mirror finish but to diffuse the large area into a series of smaller reflective surfaces the metal was ‘pleated’ at different scales. It is so smooth that the finish is virtually self-cleaning and the exterior ‘curtain’ concept has been taken into the outer fringes of the interior.

Stainless steel is being used in diverse projects ranging from self-builds to transport infrastructure. The new Galashiels interchange building has been much in the news following the long awaited re-opening of the Borders railway linking to Edinburgh. It has a durable matt façade in what was also designed as a ‘statement building’. Given the predisposition to consider stainless steel as uncompetitive against other metals, the most critical element in this particular project was that, by virtue of weight and gauge of material used, it saved more than £11/m² over anodised aluminium.

Once installed, stainless steel presents no risk to potable water and will not stain masonry or timber. It is 100% recyclable so can be used to re-manufacture roofing, façade, rainscreen or rainwater products. An exceptionally high melting point gives high fire resistance, while the material’s tensile strength is twice that of copper and more than four times that of aluminium. For over 100 years, the metal’s high performance has prompted use in the most demanding industries and environments. Now, outstanding corrosion resistance and design life are prompting use of stainless steel in increasingly complex specifications. With demands for high end aesthetics and low maintenance, it is surely set to be specified for an increasingly high proportion of projects.

Aperam Stainless Services & Solutions UK Limited
9 Midland Way, Barlborough Links,
Barlborough, Derbyshire. S43 4XA
T: 01246 571660
E: kevin.jones@aperam.com
www.uginox.com

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