McAlpine Design Group shortlisted for BCIA 2024

The team’s innovative approach to the Westbury Hotel refurbishment project has earned us a nomination in the Temporary Works Initiative of the Year category.

Brought to you by the Institution of Civil Engineers (ICE) and New Civil Engineer, the BCIA are one of the most prestigious awards in the built environment sector that seek to recognise and reward excellence in project delivery and, crucially, delivering positive outcomes for society.

The Westbury Hotel, an iconic 8-storey building located in Mayfair, has been a landmark since its construction in 1955. Our project involved extensive refurbishment works, which included:

• The addition of an extended new double-storey basement
• Demolition of a substantial part of the building at the rear, followed by the extension of the ground floor and subsequent construction of new, enlarged floors above
• Demolition of Level 07 and part of Level 06, replaced with a more visually appealing structure

One of the most significant challenges was constructing an additional basement under the existing single-storey basement. This required the retention of the 7-storey concrete frame above while excavation and strip-out works were carried out on all upper floors. Limited structural information at the time of tender added to the complexity and risk of the project.

Our solution involved the installation of temporary deep foundations to facilitate excavation beneath the existing structure and the breakout of existing strip footings. Given the low headroom and restricted working area, we chose a mini piling rig capable of installing 300mm diameter piles.

A total of 92 piles reinforced with 193.7x9.5 CHS steel tubes were installed around the 23 existing columns. These CHS plunge columns were installed in 2m long segments, with threaded ends allowing for continuity and full structural capacity.

Temporary steel frames were then installed atop the plunge columns, each supported by four columns surrounding one existing concrete column. Specially designed steel brackets were fixed to the concrete columns to bear the full gravity load. The critical stage was the load transfer from the existing foundations onto the temporary frames, achieved using hydraulic jacks and a strict monitoring regime to ensure controlled loads and movements.

Following successful load transfer, the existing concrete columns were cut below the line of jacks, allowing for the demolition of the existing foundations and subsequent construction of new pile caps. UC steel extensions were installed between the new pile caps and the cut columns, with the jacks released in a controlled manner, resulting in overall observed movement of less than 3mm—well below the 5mm design limit.

The basement extension was crucial to the success of the entire project. Our collaborative efforts with the piling contractor, steelwork contractor, temporary works engineers, and project site team ensured timely and cost-effective delivery.

Congratulations to everyone involved in the Westbury Hotel project and best of luck for the awards ceremony which takes place on 9^th October.