Contemporary Architecture

Harry Seidler – Capita Center

The building:

  • Type: Office Building
  • 34 levels above ground (3 storey lobby), 2 basements
  • Total floor area: 32,155 sqm
  • Material: composite steel/concrete
  • Support Structure: External columns and lateral bracing beams


  • Location: Castlereagh Street in the centre of Sydney city
  • Irregular,tight, landlocked site
  • Open only to the East

Architect’s Desire:

  • Modernist
  • Ground floor is open to the public
  • controlling sunlight with external louvres to the North and East
  • Bold and expressed structural system

Design Decisions:

  • Core is located at the perimeter of the site
  • Clear rectangular area
  • ž6 col free spaces => manipulated as 1/3rd of each floor is a void
  • žprovide all parts of the floor with some level of natural light from the atrium
  • žmaximum integration of services to minimize ceiling depth to allow for a higher ceiling appropriate to a prestige office building
  • žProvided a small oasis in the middle.
  • Favourable to the client: enabled them to build an additional five floors, under the FSR regulations at the time.
  • Underground parking
  • The building lacked adequate lateral stiffness -voids through the building restrict the opportunity to gain continuity within the structure
  • Only possible on east façade => east wall-shear wall
  • A composite system -faster construction, services penetrations through the beams and efficient spanning of the large grid.
  • The floor system allows the office areas and glazed facades to be free of columns

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