Institution of Structural Engineers HQ, London

The Institution of Structural Engineers HQ is a retrofit of a four-storey 1960s office building which has now been transformed into a modern, thriving workplace. It celebrates a spirit of collaboration between architect, engineer and client, showcasing the application of sustainability in retrofit.

A finely detailed, horizontal-cantilevered staircase in precast concrete and steel is a contemporary  reinterpretation of the traditional cantilevered stone stair that characterised the institution’s former building on Upper Belgrave Street. The staircase is supported by a feature wall of immaculate board marks, using Douglas fir, the idea being that the wall would display how timber shuttering could be specified with self-compacting concrete to create a visual masterpiece. The treads are supported by a gracefully-shaped minimalist red steel stringer and formed in white precast concrete punched with cast glass lenses which diffuse light through the stair. The treatment continues in the atrium bridge opposite, where the shape of the bridge reflects the structural bending moment. Set behind the new glazed double-height façade and illuminated at night, the stair is clearly visible from the street, and will become a motif for pioneering design.

The retrofit incorporates passive sustainable measures including thermal improvements to the walls and roof, achieved with high levels of insulation and reduced air permeability. Minimising the requirement for new structure limited resource use and the associated embodied energy. New materials have been responsibly sourced from suppliers with environmental accreditation. In the construction of the concrete wall, the Douglas fir timber shuttering was reused elsewhere in the construction.

Featured in CQ Summer 2015 (pg11)