5 Aug 2016

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Sustainable gold aluminium for stunning landmark

Aliva UK was commissioned by architects Sheppard Robson to develop an eye-catching, 3D-effect façade in sustainable aluminium mesh that would bring vitality to hospital parking or visitors. The result: an old car park transformed into a striking local landmark. But as Sales Director Justin Price explains, the development needed intensive input from Aliva UK’s team of technical experts.

We were brought onto the Grafton Street car park project by architects Sheppard Robson, whose brief was to extend the existing car park and create a striking landmark for the Central Manchester University Hospitals NHS Trust’s complex.

The car park building is normally seen from the side, not face-on, so the architects wanted cladding that would ‘step off’ the building, pushing out a further 800mm.

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Sheppard Robson specified a metal façade that would not only enhance security, but also provide a minimum 75% natural air-flow to help the building breathe without the need for mechanical ventilation. This was a vital consideration due to exhaust fumes in the car park.

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The architects also wanted each cladding panel to be exactly aligned with a parking bay, giving every vehicle its own gold façade.

As well as the aluminium mesh cladding that spanned the floor spaces of the car park, the architects wanted silver horizontal bands to encompass the building on every other floor.

The final aesthetic challenge was to meet the planners’ and architects’ requirement for a visual ‘story’ for the building at ground level.

Working with Sheppard Robson’s design, we developed an anodised aluminium expanded mesh façade that stood away from the building to create depth and impact. The panels of mesh were each folded to a crisp point, resulting in a façade that could be seen at every angle.

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Achieving the right finish

Expanding aluminium and punching it with apertures weakens the metal. Folding it to a perfectly crisp point weakens it further. Because of this we needed to find a combination of the right aperture sizes and folding techniques to ensure that the cladding allowed enough ventilation, looked perfect from an aesthetic point of view, and also maintained its structural integrity.

To do this, we tested a variety of aperture sizes and folding techniques. The tests needed to show that the cladding could withstand the worst of the elements – rain, wind, snow. At the same time, each fold needed to be perfectly crisp, so that when seen from below, each panel would be exactly aligned. We arrived at the final specifications and design through a series of prototypes.

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Installation of the cladding

Our original plan was to secure the cladding to the floor slabs of the car park; however, this was not possible for two reasons.

First, the building was on a gradient. This meant that if the silver horizontal bands specified for every other floor were fixed to the floor slabs, they would also appear to be sloped, which would not create the right aesthetic.

Second, it was found that if a car were to hit the internal crash barrier at maximum speed, the barrier would deform out to 138mm. This meant that the cladding could not be installed against the building in the normal way.

To resolve these issues, we designed an entirely bespoke fixing system. This involved hanging the cladding panels from wind posts around the building, so that the cladding wrapped around it, without being supported by it.

Despite there being minimal physical interaction between the internal structure of the building and the cladding, the cladding still had to interact with the inside of the building to meet the requirement for each panel to be exactly aligned with a parking bay. Our wind post solution was able to meet this challenge too, ensuring there was still a relationship between the external and internal parts of the building.

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Screen printing

To meet the requirements of the planners and architects for a visual story at ground level, Aliva UK’s design for the façade base featured a bespoke, screen-printed urban landscape that created a focal point for visitors arriving at the hospital by car.

While screen printing on intact panels of cladding is comparatively straightforward, ensuring that the images still appeared recognisable on mesh was one of the key challenges here. Again, prototyping helped Aliva UK’s team to achieve the desired finish. The final look was achieved by first expanding and anodising the metal, then building up the screen printed design in several layers.

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The resulting building is something that both we and the architects are extremely proud of. It is now a landmark in the local area, providing a vital resource and welcoming face for the hospital complex.

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