Sumner Road, Southwark

The development at Sumner Road in Southwark consists of a U-shaped building with up to 10 floors of flats, studios and live/ work apartments over a basement car park.  The superstructure is a concrete frame, with a heavy transfer slab at ground floor level. The basement is contained within a steel sheet piled retaining wall.  The penthouse apartments at the top floor level are steel framed.

The site is underlain by gravel, which has a relatively high bearing pressure, so we were able to reduce the construction cost by using reinforced concrete pad bases rather than the more expensive piling.  To allow settlement of the framed structure, which is on shallow pad footings, a sliding joint was designed which maintains the propping action of the transfer slab against the capping beam of the sheet-piled retaining wall.

The basement car park is ventilated by concrete turrets disguised as garden features in the front and rear courtyards, requiring complex analysis of the transfer slab with large openings. 

To maintain rapid progress of insitu flat slab upper floors, no upstands or cast-in fixings were permitted. All galvanized steel balconies, stainless steel brackets supporting brickwork and brackets restraining the timber cladding were retro-fixed to the slab edge with resin adhesive anchors after the frame contractor had left site.   To allow horizontal thermal movement in the floor slabs the U-shaped floor plate was subdivided into 3 separate blocks by floor joints.  

An unusual feature of the development is the external timber frame that forms a decorative feature on certain elevations.  This is up to 10 storeys high, and consists of sustainable tropical hardwood.   Some innovative details were required when designing this frame, to take account of differential movements relative to the main part of the building.