• 16 January 2018

K1 Knightsbridge

A prestigious retail scheme in the most exclusive part of London

Knightsbridge in London is one of the most exclusive shopping locations in the world, a vibrant location which has attracted super brands, high-end designers, upmarket restaurants and wealthy residents.

It is in the very heart of this sought-after area, between Sloane Street and Brompton Road, where the redevelopment of Chelsfield’s K1 Knightsbridge Estate seeks to reinvigorate, restore and celebrate this significant scheme.

The 33,000m2 redevelopment comprises a 7-storey mixed-use building with retail at street level, residential apartments surrounding a secluded rooftop courtyard garden at the second floor, office space and a roof top restaurant with panoramic views. The 3-storey basement will incorporate retail space, delivery vehicle access, car parking and plant rooms.

Innovative solutions to numerous challenges 

This is an exceptional project with various site constraints and challenges, many of which require extreme attention to detail and precision to overcome. Working closely with Chelsfield, we have been appointed to provide structures, civil and environmental consultancy services for this prestigious scheme.

The redevelopment involved the demolition of most of the buildings, however, as the site is located within RKBC’s Hans Town Conservation Area and includes a Grade 2 listed building, all the existing façades facing the main external streets had to be retained. Our teams have had to carefully consider the constraints of its location being above the current LUL Knightsbridge Underground station. These included the relocation of an existing tube entrance, pavement widening along Brompton Road and Sloane Street as well as a new step-free access to Knightsbridge station. In close consultation with LUL Asset Protection, we are continuously carrying out structural investigations, ground movement analysis and automated and manual movement monitoring to ensure the construction is safe and seamless to all surrounding infrastructure assets.

New Superstructure

As for the scheme’s main construction, our structures team has designed a new superstructure combining reinforced concrete and steel frames. It is founded on rotary bored piles with secant piles to the perimeter of the 3-storey basement. The key challenge here has been to design the sub & superstructure over and adjacent to the London Underground infrastructure. Several transfer structures have been resourcefully incorporated within the frame while minimising loss of headroom or area. We achieved this by introducing storey-height concrete beams, ‘deep beams’, within party walls between the different demises.

The spacial arrangements for the office, retail and residential space are all different and this is evident by the choice of the structural materials. The office building has been designed in structural steelwork to achieve the column spacing of 11.5m in one direction whilst the retail and residential spaces have been designed in concrete with a structural grid of circa 9.0m. The junction of the steelwork and concrete share the same columns and we have carefully taken into consideration to build a sequence to provide an efficient structural frame in a single row of columns.

Another structural challenge has been to retain the façade which has influenced the floor to floor heights and the spacing of the new columns around the perimeter of the building. The office has been designed to meet BCO guidance with a floor to ceiling height of 2.7m which has required the beam deflections to be minimised and the construction tolerances to be specified in detail.

Detailed ground investigations 

Desk-based environmental assessments of the site revealed former uses such as milliners, bootmakers, furrier and dry cleaners and this has required our specialists to proceed with further geotechnical and environmental ground investigations.

A second phase of ground investigations are currently underway to establish the groundwater quality in the underlying natural gravel. We are assessing the potential ground contamination and ground gas risk to the finished development. The data captured is also utilised in our ground movement analysis which supports the asset protection process.

Richard Papworth, Structures Director said; “This is a unique and prestigious project for us involving complex engineering with several constraints on the site. The scheme’s proximity to the London Underground and nearby buildings incorporating the retained façade has allowed us to be creative and innovative whilst carefully planning every step of our solutions.”

Waterman has been involved in K1 Knightsbridge since its conception in 2013. The project is due for completion in early 2020.

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