The Westin, City of London
A mixed-use development featuring a five-star hotel, conference centre and riverside apartments in the City of London that posed problems due to its restricted location led us to develop a highly-efficient solution, retaining elements of existing office buildings across the site.
The complex site features five scheduled ancient monuments, and buildings on either side of Upper Thames Street, connected via a bridge carrying accommodation. This link structure was a key challenge, as any demolition or construction works would require road closures and obtaining possession approvals.
We proposed retaining the 1.5 m-deep concrete deck structure, supported on concrete beams. This allowed demolition of the building above, and subsequent construction of new hotel accommodation, without closing the road.
The situation was further complicated by a requirement to shift the structural grid of the building above laterally, applying torsional loads to the deck due to the structure cantilevering. Our proposal was to tie the longitudinal beams together, minimising complex strengthening works.
Lightweight concrete was specified for the new superstructure, with post-tensioned floor slabs delivering the shallow floor-to-floor depth needed to meet the required number of storeys within a predefined envelope.
At the northern end of the bridge, the lower two levels of a new seven-storey structure feature double-height spaces for a conference centre, with large spans necessitating major load transfer structures.
At the site’s southern end, an adjacent residential building is connected to the existing Queensbridge House, relying upon it for stability. We solved this structural challenge by inserting steel plates across a movement joint, providing additional stability for the new building and allowing the existing building to be demolished.
Other initiatives include retaining existing foundations and basement columns within this part of the site, minimising the need for new piling thus minimising the impact on the Roman remains beneath the site. We analysed the existing basement structure and matched new superstructure to the existing foundations wherever possible.
Five-star hotel with impressive glass cladding throughout, conference centre and apartments
4C Hotel Group
Dexter Moren Architects
£ 59 million