CA avoids the curse on world’s first total cast facade.

The opening of the Arc as a new Debenhams store.

CA GROUP, has completed its most complex job ever – a cast aluminium façade on The Arc retail development in Bury St Edmunds. The building is part of a mixed-use redevelopment of the shopping centre of the historic market town, and has this month opened its doors as a new Debenhams department store.

Even years before the building reached this stage, though, it was being talked about for many different reasons. Throughout the process of its creation, the project has impressed many thanks to its stunning, architecturally daring appearance, and the technical complexity of the metal cladding.

The project features 3,200 square metres of sand-cast aluminium panels made to order by CA’s bespoke architectural engineering division Execa, and is thought to be the first time a building has ever used such a method for a façade. The 2085 panels are of 254 different types, and form a free-flowing curved surface to give a futuristic exterior to the building.

Curiously though, in 2005 while the development was still on the drawing board, it hit the headlines in the local area for a very different reason. Clearly not so impressed by such ultra-modern architecture, a controversial religious group calling themselves the Knights of St Edmund invoked what they claimed was a 1000-year-old curse on the developer and client for planning their flagship development for the centre of the medieval town. Painful deaths were threatened for all involved in the project, including being eaten from the inside by worms.

Thankfully undeterred by this prospect, architects Hopkins and Associates went ahead and created a shiny metallic finish made up of thousands of diamond shapes, which are uniformly spaced to allow subtle blue neon illumination from behind. Nick Belden, the head of CA Group’s Execa division, explains the complexity of this unique project:

“In order to create this amazing building, we needed to utilise our state-of-the-art 3D surface modelling software, similar to that used in the automotive and aerospace manufacturing industries. Architects work with very sophisticated CAD packages, and we needed to use a system that could accurately reproduce their designs and engineer complex forms and structures. The whole process from design to manufacture has been paperless.

“The architects came up with the idea of this façade treatment, and we investigated lots of different manufacturing processes. The sand-casting method, creating moulds out of sand and setting with epoxy resin, was deemed to be the most effective method of creating the many complex forms and shapes.

Much of the complexity was in the patterns. The fluid curves of the finished building give the impression that each individual plate is unique as they flow in different directions, but in fact we worked from 54 “parent” shapes. From these we created a family table of panel variants and sub-variants, which simplified our manufacturing process behind the scenes and allowed us to keep costs down.”

After the sand-casting process, the plates were then coated in a clear protective lacquer – similar to that used on the hulls of ships – to give a durable and attractive surface finish.

Behind the unique façade, the outer envelope of the building is clad in CA’s industry-leading Twin-Therm^®, which gives a non-combustible, non-fragile skin that guarantees U-values to comply with both current and proposed Building Regulations.

In order to make life easier for the cladding contractors on site, CA has also applied its expertise in creating a simple and robust fixing system. Most importantly, each panel had its own unique serial number and orientation arrow stamped to the back so as to eliminate the possibility of mistakes in installation. Holding the panels in position is a straightforward fitting kit of bosses and lugs, with which any cladding contractor would already be familiar.

As a result, despite the unprecedented complexity of the cladding, this phase of the project has run on time and on budget.

Nick Belden concludes, “We are justifiably extremely proud of this achievement and The Arc is currently being entered for the Casting Of The Year Award. I’m also delighted to add that so far, to my knowledge, none of us has suffered any curse-related misfortune!”