The original site comprises an existing single-storey building and external courtyard space, located behind the two main Grade ΙΙ listed villas.
This adjacency to existing buildings was immediately identified during the pre-construction phase as a key area of design risk, and early works involved re-evaluation of the basement perimeter, to increase the area between existing buildings and the boundary, whilst maximising the footprint to accommodate a lecture theatre, cinema, and plant room.
As the basement encompasses the entire footprint of the site, effective logistics management is critical to the success of the build.
Surrounded by buildings with mixed ownership, this scheme has complex party wall challenges that were all fully investigated during the early design stage.
As the Risk Schedule identified the basement design as the area of highest risk, ISG and the design team appraised various re-design options.
The priority was to re-design the basement perimeter, with the requirement to both minimise risk to adjacent properties and enable sufficient space to construct the retaining walls. By re-positioning the plant room and subsequent risers, whilst maintaining the position of the lecture theatre, adequate space was created.
The second challenge was the design of the retaining structure and its subsequent effect on wall design. With budget and programme constraints to consider, a hybrid solution was developed, which moved away from the simplest option of using contiguous piling in all three areas.
• Contiguous pile wall to part of the perimeter as a retaining system for two sides of the lecture theatre on the North East of the site, this is pinned with free standing cantilevers
• Slope batters at 2.1m for remaining basement wall structure
Wall design solution;
• Waterproofed contiguous pile wall with masonry face, incorporating drainage gulley
• Precast wall favoured for remaining walls, with integrated damp proof membrane and stone backfill placed between the building’s steel frame structure