Deccan Studio Offices

The client had bought a tired four-storey commercial building from the mid-1970s and assumed they would demolish it. They asked us to confirm that assumption. We came back and told them not to, which was not what they had budgeted for hearing.

The existing frame is a reinforced concrete grid at 4.8 metres, structurally sound apart from spalling on the exposed western edge, with 2.9-metre floor-to-floor heights that are tight but workable. The building sits hard on the pavement on a busy street with no setback, so any external work had to happen from inside or from a licensed scaffold over a footpath the municipality would only close at night.

We kept the frame and the slabs and replaced everything else. Retaining the structure saved roughly nine months of programme and — by the client's own quantity surveyor — about 31 per cent against a new build of the same area, before counting the embodied carbon that never had to be spent twice. The repair work on the western columns took six weeks and cost less than one floor of new frame.

The 2.9-metre floor-to-floor was the real constraint. With services in a suspended ceiling the rooms would have finished at about 2.4, which is oppressive for an open workspace. So the services run exposed in a defined zone against the corridor wall, painted out, and the slab soffit is left visible and simply sealed. That recovers 300mm of clear height across every floor and is the single most-noticed thing about the building by the people who work in it.

The new envelope is a rain-screen of fibre-cement panels on a light steel sub-frame, fixed back to the existing frame and installed entirely from a scaffold erected and struck between eleven at night and six in the morning across nine weeks. Where the old frame was out of true — and a 1970s frame always is — the sub-frame takes up the tolerance. Detail A-501 shows that adjustment zone, which is the drawing this project actually turns on.