Project Pentrak, City of London

This was a complex central London refurbishment and new-build office construction behind a retained facade to create modern space for City & Guilds.

It required the retention of three 1920s era facades at 5, 6 and 7 Giltspur Street, plus two cores of the existing buildings, a former office and public house. These had sustained bomb damage and undergone previous restoration. The new seven-storey structure was constructed around the retained building elements.

Facilities

The completed development has 4,650m² of open plan offices, meeting space, and a cafe, plus a retail unit at ground floor, over seven storeys.

Temporary works

The tower crane base design involved installation of 108 mini piles at 7 Giltspur Street and a 2m-deep piling mat. A well was discovered beneath the building which required the last-minute alteration of pile positions.

The base design also had to accommodate underpinning work on an existing basement and construction of the lift pit underneath.

Demolition and refurbishment

The first phase of the scheme included the partial demolition of a six-storey building behind a retained façade at 5 and 6 Giltspur Street. The main roof and four upper floors were removed.

The lower floors were refurbished, with new new upper floors and a new roof plant enclosure constructed.

This phase included infilling of two light wells to form a new secondary fire escape staircase and construction of additional office accommodation in 5 and 6 Giltspur Street.

Steel-frame new build structure

The second phase of the scheme centred on the steel-frame construction of a seven-storey office building at 7 Giltspur Street, plus retail units at ground floor level, and basement levels. The structure was erected behind the existing facade.