Striking steel construction for commercial and catering trades

In Bishops Square Retail, a commercial and open space project in London's Spitalfields, a 70 metre-long and 15 metre-wide structure creates an eye-catching landmark in Lamb Street. With its red oxide steel frame, the Lamb Street Building is reminiscent of the industrial buildings and warehouses that once characterised London's East End. The ground floor houses ten retail and catering outlets. They are designed to enable flexible use of the building throughout its entire useful life. A larger retail unit on the first floor is accessible via a building-height foyer at the western gable end.

The design aim was to showcase the industrial character with steel beams, visible fixings and red oxide steel. That's why the thermal building envelope (a continuous structural glazing façade) was constructed behind it and aluminium and steel façade systems were combined. The storey-height shop fronts on the ground floor and the retail unit on the upper floor were fabricated using the Schüco FWS 50⁺ SG aluminium system. The Schüco AD UP 75 system with concealed hinges and door-height pull bars was used for the entrance doors. For the building-height atrium, the architects opted for the Schüco VISS SG steel system. “The two systems are virtually identical in terms of look and performance, but the VISS SG steel system can span double the height,” the architects explained. “Given the similarity of the two systems, the combination of aluminium and steel façades offered the optimum solution in terms of cost-effectiveness.”

The details of the curtain walling from the Schüco VISS SG steel profile system, including the glazing clips, were developed by project partners VolkerFitzpatrick, Nuëcø Facade & Glazing Solutions, Foster + Partners and Bond Bryan in close collaboration with one another. The main aim was to ensure that the red oxide steel frame remained the primary design feature, while also fulfilling functional requirements in terms of watertightness, wind loads and air permeability, as well as preventing thermal bridging.

Installing the up to 800 kg curtain walling units behind the primary steel construction posed a significant challenge. At the top and bottom end, the Schüco VISS SG curtain wall is fixed to the primary construction by means of project-specific, custom-made glazing clips. It is unsupported laterally, so that it can sway with the building. Two steel mullions and a U-shaped profile have been joined together in such a way that they appear unsupported in one length, and are then cloaked to appear seamless. The glass-to-glass corner joints proved to be particularly challenging. For this, the standard VISS SG profile was modified to allow it to be installed at a 45-degree offset, to maintain the glass edge support on both sides. The mullion, which has been reduced as much as possible in terms of form, provides an optimum view to the outside.