100 New Bridge Street

Keltbray supported Mace in the redevelopment of 100 New Bridge Street, delivering a programme of structural alterations and new steel and concrete works across the existing building. The scope included a full soft strip, cladding removal, demolition of plant rooms and satellite cores, and selective slab and column removal. The team also designed, supplied and installed new steelwork, including a three‑storey office extension and a Vierendeel truss to replace the former reinforced‑concrete core. 

Sustainability targets shaped the project from the outset. The scheme aimed for high circular‑economy performance, achieving extensive material retention and waste reduction. By reusing 91% of the reinforced‑concrete lift cores and 85% of the reinforced‑concrete walls, the team significantly reduced the need for new materials. Mace estimated that these measures saved 1,795 tonnes of CO₂e, supported by early collaboration between Helical, Keltbray, Mace and the wider project team. 

The project demonstrated how the circular economy can be integrated into central London redevelopment. By combining structural demolition, steelwork installation and new sub and superstructure elements with a sustainability‑led approach, the team delivered a scheme that met both contemporary performance standards and carbon‑reduction ambitions. 

Project outcomes  

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