one-page-street-03-©-PLP/Architecture
© PLP/Architecture

One Page Street

Complete refurbishment of this office building in London’s Westminster highlights the added value that structural engineering can bring to a project. Significant extra space – approximately 12 % – was added with minimal changes to the existing structure, thanks to our expertise in working at the limit of current and historical design codes.

Originally constructed in the 1960s as part of a hospital, the seven-storey concrete-framed building on Page Street was converted into offices in the 1990s, with additional space provided by steel-framed extensions on the roof and along its southern flank.

We were commissioned to explore ways to deliver even more lettable space, by adding on a further storey plus cantilevered side extensions while ensuring the existing structure can cope with any resulting increased loads, since internal strengthening is expensive and time-consuming to carry out.

Initially, we carried out a major investigation and detailed analysis of both the existing foundations and superstructure. This provided a full understanding of the structure and its strength. All assumptions made in their calculations were confirmed by careful testing and exploratory work on site, further necessitated by the lack of existing records about the building’s structure.

In terms of the foundations, the analysis needed to ensure that any additional loads would not cause either settlement beyond acceptable levels or overstress the existing foundation structure.

With regard to the superstructure, new structural elements were designed to be as lightweight as possible, to keep additional loading to a minimum without compromising the dynamic performance of the building. Proposed measures include the use of lightweight concrete for composite floor slabs. Detailed analysis ensured that any column strengthening needed as a result of the alterations was provided only where required, while strengthening to existing steel beams has been designed to increase the allowable floor loads.

Refurbishment and lightweight extension of a concrete office building

LOCATION
London, UK
CLIENT
Derwent London
ARCHITECT
PLP Architecture
PROJECT VALUE
£ 23 million
COMPLETION
2014

AWARDS
  • 2015 Civic Trust Award
  • 2014 New London Award – Commendation