south-bank-tower-01-©-KPF
© KPF
south-bank-tower-02-©-KPF
© KPF
south-bank-tower-04-©-KPF
© KPF
south-bank-tower-03-©-central-photography
© Central Photography
south-bank-tower-05-©-KPF-and-central photography
© KPF and Central Photography
south-bank-tower-06-©-paul-harmer-and-KPF
© Paul Harmer and KPF
south-bank-tower-07-©-AKT
© AKT II

South Bank Tower

Updating the tired façade of the thirty-storey King’s Reach Tower on London’s South Bank was just the first stage of its transformation into a desirable mixed-use development. Both the tower and neighbouring podium have been raised in height, and new basements and an atrium constructed.

Raising the tower by eleven storeys meant detailed analysis of the existing structure and foundations. As the perimeter structural fins couldn’t take additional load, the new storeys cantilever from the core, which has spare load capacity and allowing it to be extended upwards.

The podium has been reconfigured to provide extra floor space. There were four cores along its length, separated by movement joints, and we sequenced a critical process to replace these with new perimeter cores and stitch the joints together.

Three storeys have also been added above the podium, constructed with a steel frame to minimise loads. Strengthening of the podium’s superstructure and foundations was required to accommodate additional loads. Steel columns have been punched through existing concrete floors, taking loads from the structural additions down to the foundations.

A two-storey basement has been constructed under part of the site. Being close to the Thames, and extending below the water table, it posed significant challenge to resist buoyancy forces. As it penetrates low-permeability London clay, we recommended incorporating a means of draining water from beneath the basement slab, reducing the need for tension piles to resist uplift.

Finite element analysis allowed us to model the ground underneath the site, examining different stages of construction and predicting ground movements and stresses placed on the Waterloo & City line, which runs underneath. The accuracy of this analysis allowed a reduction in the thickness of the basement walls, cutting construction costs and reducing the amount of temporary propping required during construction, while also maximising the amount of usable space.

Innovative upwards extension of an existing thirty-storey office tower in South London

LOCATION
London, UK
CLIENT
CIT Group
ARCHITECT
KPF
PROJECT VALUE
£ 125 million
COMPLETION
2016

AWARDS
  • 2015 NLA Award – Commendation for Conservation & Retrofit Category
  • 2016 UK Tekla BIM Award - Commercial Projects Winner