Caxton House was a 1960s office block located next to Smithfield Market in London’s Farringdon district, ripe for commercial redevelopment. However, though unremarkable to look at, our investigations soon unearthed a complicated network of services weaving across the footprint of the building.
Underneath the site’s southern edge lies a road tunnel, while beneath the adjoining Port of London Authority Building are railway sidings. A large brick sewer runs across the site, its crown just below basement level. Nearby is the dormant Post Office underground train tunnel. With busy Farringdon Road along the building’s eastern boundary, there are various constraints to developing this urban site, requiring negotiation with multiple parties.
Now demolished to basement level, in Caxton House’s place will rise the new 16,800 m² Charterhouse Place mixed-use development, designed by Lifschutz Davidson Sandilands. The new building will feature a steel-framed superstructure incorporating a number of load transfer structures because of the large ‘cut-outs’ that articulate the façade. The need to maximise the amount of lettable space within the planning envelope, while creating maximum headroom within each storey, prompted us to recommend shallow beams topped by 130 mm thick composite slabs, spanning up to 13 m.
Construction work is proceeding concurrently with ongoing Crossrail work to the north, necessitating constant liaison and approvals to ensure the projects do not impact detrimentally upon each other. Following substructure analysis which revealed that existing piled foundations lacked sufficient capacity for the new building, we have proposed a new 1.6 m deep foundation raft to minimise disruption. We undertook 3D finite element ground modelling to show that loads from the new building would not exceed the design loadings of the adjacent station box, and the subsequent design was required to provide tolerance for ground movements caused by the tunnelling.
Redevelopment of a prime office location close to Farringdon’s Smithfield Market
Henderson Global Investors
Lifschutz Davidson Sandilands
£ 110 million