A staircase cantilevered from a concrete spine wall The staircase and lift shaft rise at the centre of a 12 x 30m courtyard with an undulating concrete roof. It is enclosed by two six-storey office blocks, raised on columns above ground floor level to encourage the movement of air through the courtyard to cool the space. Landings, lift shaft and staircase are all of cast in situ concrete - local labour and materials were used wherever possible - with a glass plank screen forming the rear walls of the lift shafts. The landings project from the edges of the floor plates and stiffen the lift shaft walls.
The staircase is a dogleg with curved half-landings; cast in situ treads and risers cantilever from a concrete spine wall, clad with white glass mosaic tiles. (The flight from ground to first floor leads off at an angle to accommodate the extra height of the ground to first floor column structures. ) Treads, with non-slip grooves and bull-nosed edges, and risers of 25mm buff-coloured marble are laid on a 10mm adhesive bed. The edges of the staircase are clad with fascia panels of similar marble; their lower edges slope to follow the line of the string; their upper edges are stepped to align with the tops of successive treads. The panels are resin-doweled into the concrete structure.
A balustrade of 15mm toughened glass and a 50mm-diameter stainlesssteel handrail protects the landings and staircase. The bottom edge of the glass slots between the marble fascia panels and the concrete structure, clamped in a 120 x 10mm U-shaped steel plate, fixed with countersunk bolts to the concrete. The joint is sealed with mastic. The staircase soffit is finished with a textured acrylic render.