In revising the structural design for the concrete frame, architectural constraints, such as floor depths, were kept unchanged. Floor slab thicknesses have been rationalised, and columns moved into the walls to increase usable floor space. A series of transfer structures were needed to achieve the building’s profile and these have been revised for efficiency. No amendments to the planning permit were required.
The architect’s strategy for the building responded to the existing townscape in its massing, extending the adjacent building lines and street frontage to the north and east. This is achieved using step-backs — at different levels on all four elevations. On the north facade, the first floor cantilevers, requiring an area of transfer slab and transfer walls to support the nine floors above. Instead of steel transfer beams, our solution uses concrete walls acting as deep beams running the full height of the building.
All 32 apartments, half of which are affordable, include a tapered cantilevered concrete balcony, with thermal breaks to minimise cold bridging to the floor slabs. The building is clad in brick suspended off the slab edges.
The building’s footprint occupies the entire site, so the drainage arrangements are below it, co-ordinated with the locations of the structure’s CFA bored piles. As part of the SuDS strategy, the pipework was oversized to provide storage and reduce discharge rates to acceptable levels. Drainage for the balconies is cast into their slabs, with downpipes in the brickwork cavities.
Asset protection agreements with Thames Water were required, as a deep brick-lined sewer and a large pressurised water main are located in close proximity to two corners of the site. We showed that ground movements are within acceptable limits set by Thames Water. Pile locations were moved away from the main corner of the building, with foundations cantilevering to support the external feature corner column.
Bridport Place, Hackney, London, UK
Fraser Brown MacKenna Architects
Henry Construction for Metropolitan Housing Trust