Park Plaza Hercules House

Creating a new hotel from a 1960s concrete office building

Walsh played a key role in transforming this 1960s concrete-framed office building into a new 500-bed hotel near London Waterloo. The project ambitiously added five new floors, expanded the footprint, included a new annex, and the construction of a new basement.

Starting with a comprehensive desktop and archival search, followed by intrusive investigations, sampling and testing, Walsh determined the necessary strengthening works to meet the project’s swift timeline. A thorough temporary works strategy and detailed construction sequencing streamlined the final design. The site was adjacent to a Network Rail exclusion zone and we facilitated approvals whilst piling commenced.

The building was first stripped to its concrete frame allowing spaces to be reimagined. Atriums were filled to create hotel-friendly floor plans and ground-level columns were removed to accommodate a suitable lobby and reception area. Despite efforts to preserve the original core, updates to meet modern standards for lifts, stairs, and risers led to its replacement. This was expedited by off-site prefabrication of twin-wall cores.

Walsh encountered and managed complexities, including unexpected obstructions, variable foundation conditions, and fluctuations in groundwater levels. The addition of five new floors was facilitated by employing lightweight steel and a hybrid foundation system. This approach included the implementation of full-depth trusses spanning the building’s width and the reinforcement of the existing pad foundations.

To achieve uniformity across the hotel rooms, the existing building’s footprint was expanded by 15% through the integration of a new steel perimeter frame. Integrating this frame with the existing Stahlton clay infill floors, which were fragile and required preparatory opening before fabrication, presented a significant challenge. This necessitated an agile approach to detailing, significant flexibility and collaboration with the contractor. This new structural frame facilitated a modern prefabricated cladding solution which could be swiftly installed on-site.