Planning consent was, last night, granted to refurbish 318 Oxford Street, the building of landmark tenant House of Fraser. Architects PDP will work alongside us as civil and structural engineers to undertake major improvement works which will allow continued retail use in the lower levels of the building.

The refurbishment will add an eighth floor to the 35,000m2 building, boasting a rooftop restaurant and extensive terraces. The sixth and seventh floors will be rebuilt to provide high quality COVID-compliant office space while the second to fifth floors are retained and converted, also for office use.

The redesign requires the complete removal of most internal masonry walls, which provide stability to the structure. In response, we have designed a completely new stability system comprising a braced steel frame to be inserted into the former escalator well.

Considerable research was required to understand details of the existing structure, and to justify the necessary increase in height. Keeping the new structure ‘light’ allows much of the existing structure to be retained which significantly reduces the scheme’s carbon footprint. A further reduction in environmental impact is achieved by re-using some of the demolished steelwork in the new construction.

We analysed the existing and proposed loading on each of the near-1000 columns in the building. By combining information from archive records, opening-up and materials testing, they were able to justify the changes in load and eliminate the need for major strengthening works, reducing cost and embodied carbon. The embodied carbon for the structural scheme has been calculated and it exceeds LETI, RIBA and SCORS targets, achieving an A+ rating.