A cast bronze structure supporting a bronze grille screen
The south and east sides of the nine-storey office building face major City routes; their importance is reflected in the design of the facade - a highly articulated framework of bronze grilles which screen a glazed curtain wall. The glazing is divided into groups of three storey- height glazed panels by 'chevron' bay windows.
At ground and first floor the facades are stepped back to accommodate a dramatic bronze framework support structure, a series of paired 275mm diameter cast bronze columns at 7.5m centres, with yokes and spigots from which spring canted and tapering I-section bronze beams. The structure is tied back to the underside of the second-floor concrete slab.
The ends of the tapering beams support a framework - 135mm diameter bronze columns connected by I-section restraint beams - which rises from second floor to seventh floor. Purpose-designed castings connect the columns and beams. A series of bays of nine bronze grilles and shaped spandrel panels are set behind the bronze framework and screen the office glazing. The grilles are set in a rectangular frame and are hinged to open for cleaning.
The 135mm diameter bronze columns are set in front of the chevron bay windows and are connected to them with stainless-steel spigots to give lateral wind restraint. They rise to the eaves to support bronze sun-screen louvres.
The large structural elements - columns, spigots and beams - were cast as hollow sections. Both sheet and cast bronze elements were sandblasted, heated and hand-patinated to achieve a consistent colour. After patination, a wax coat was brush-applied.