Former IBM Building, South Bank

Former IBM Building, South Bank

This five-storey office building was designed and built between 1979 and 1984 by Denys Lasdun, Redhouse and Softley Architects, with structural engineers Ove Arup and Partners and construction managed by Taylor Woodrow Construction.

The building has a reinforced concrete structure arranged on a 7.2-metre grid with a 1.8-metre module, comprising columns, flat slabs and beams. External components are pre-cast concrete, with non-structural internal walls of Celcon blockwork. The external facades, clad with pre-cast panels, are finished with aggregates of varying materials and treatments. The soffits are white Polyester Powder Coated panels, installed in the 1990s as replacements for the originals. Brown brick finishes are applied beneath podium level and to pedestrian areas including paved approaches to the main west entrance, which extends up to form a podium wrapping around the north-west corner. Windows and window walls are framed in anodised aluminium. Spandrel panels are formed of insulation sandwiched between two sheets of anodised aluminium.

The plan follows a broadly figure-of-eight format with two main internal courtyards on either side of a split central core, around which the office floor plates are arranged. Office floors are lit by recessed strips of glazing and the internal courtyards, with wide terracing at the east elevation arranged around two additional narrower courtyards. The main entrance, accessed by steps, is centrally placed at the west elevation, raised on a raked podium, beneath which are car parking and loading spaces served by a ramped entrance. The former public entrance at the east elevation is at the third floor, recessed between the wide terracing.

All external elevations display strong, stepped horizontal planes of concrete panels clad with aggregate finishes and recessed glazing in strips. Parapets of non-structural pre-cast concrete to each floor have exposed aggregate finishes and are fitted with tubular steel balustrades. The external columns are concrete finished with bush-hammered granite aggregate.

The asymmetric form is most clearly expressed at the south and north elevations, with the lower three floors offset to create wide terracing to the east. Facing the former service road to the west and Queens Walk to the north, the oversailing upper floors are supported by columns. The main entrance level at the west, raised on the podium, is fully glazed and accessed by the vehicular ramp with a retaining wall. A pedestrian walkway was added to the ramp later.

The east elevation is dominated by wide terraces with external prow-shaped stair towers. The public entrance to the reception is recessed between these, marked by a distinctive prow-shaped stair accessed by steps from the lower floors, leading to the glazed entrance via an aggregate-finished footbridge. Plant towers form sculptural elements on the roof, one bearing the initials 'IBM' in distinctive white lettering, referencing the National Theatre's fly towers to the west.

The interior layout is believed to remain largely as Lasdun planned, with circulation arranged around two main cores, each with its own internal courtyard on either side of the entrance hall, each fitted with two lifts and a stair and provision for a third lift to enable sub-letting of spaces if required. The majority of office floors are used as open-plan office space fitted with twenty-first century glazed walling to individual offices and meeting rooms, with some floors opening onto external terraces. The main entrance lobby has been reconfigured and internal fixtures, fittings and finishes have been replaced.

The building sits within a landscaped 'moat' and is approached via the ramp to the west.