40 Chancery Lane.

When prestigious developers Derwent purchased this plot in a vibrant corner of the City of London, close to Chancery Lane station, they sought to replace several existing, dilapidated structures with a U-shaped series of connected office blocks surrounding a rear courtyard. The resulting design combines stone and glass in a sleek façade that envelops the structure’s flexible interior.

Location

London, UK

Client

Derwent London

Architect

Bennetts Associates

Project Value

£30 million

Floor Area

9,460 m²

Status

completed 2015

Expertise

Structures

On purchase, the site housed four buildings dating back to the nineteenth and twentieth century’s. The first phase of site works comprised the demolition of all buildings except Tooks Court, the Victorian façade of which was to be retained, and the floors replaced.

Subterranean constraints introduced a number of complications: there was a risk of unexploded ordnance, so we undertook detailed investigations before and after demolition. We used ground modelling to ensure that demolition, and the resultant heave, would not affect the foundations of adjacent buildings, liaising with party wall surveyors to produce the relevant condition surveys.

We specified a 1 m-thick raft foundation below the single-storey, continuous basement, founded in the terrace gravel stratum; the stiff design of the slab is able to distribute building loads uniformly across the site. Sections of the basement were defined as plant zones, and in these areas of increased weight we proposed localised thickening.

The linked structures above the basement comprised post-tensioned RC frame construction. In certain locations visual concrete was the architectural desire, and we assessed a variety of methods for achieving the highest possible standard of finish, providing recommendations to the architects and contractors. Three reinforced concrete cores provided lateral stability, working alongside non-structural, steel scenic lifts that face out towards the landscaped courtyard. These scenic lifts have fin walls unrestrained up to a height of almost 20 m.