A complex engineering project in a very inaccessible street in London city centre. The Client, Goldcrest Films, needed a fully isolated, double-level, underground cinema studio. The engineering challenge was to excavate under the brick walls of the existing building to 10 metres below ground level while keeping the 5-storey office building above fully operational.

The solution was to excavate two floors of basement from underneath the existing office building in Soho. In tandem with the excavation, our design allowed for the full renovation and restoration of the existing office building, which was a UK listed structure built on the remaining foundations of a Victorian structure that was destroyed during the war.

SDS design engineers demonstrated our ability to find solutions to complex engineering problems while having a clear understanding and responsibility for the costs. We developed a scheme to combine temporary and permanent works. We re-engineered the basement design and introduced a kingpost-supported excavation technique that allowed temporary and permanent works to be completed concurrently. This allowed an accelerated construction program while achieving maximum gross internal space in the new studio.




  • Creation of a new basement with a floor level approximately 6m below street level while maintaining a fully-operational 5-storey office building above.
  • Working within confined spaces and limiting percussion / vibration to agreed and acceptable levels. The only access to the site was through a 4-foot-wide door, which meant that the piling rig had to be dismantled and then reassembled as it would not fit through.

Kingpost piles with in-situ reinforced concrete skin walls were adopted to avoid horizontal propping and shoring – there would have been no space to excavate the basement if these were installed. This temporary works solution was combined with the permanent structure design and allowed a thinner wall and thus increased the internal dimensions of the space.