A Building within a Building

The Grade II*- listed Battersea Power Station has been sympathetically transformed into a vibrant twenty first century destination as part of a 42-acre regeneration of this former brownfield site. In this article, we look more closely at some of the engineering challenges of designing a building within a building.

Some of the biggest challenges facing the design team on the Battersea Power Station project revolved around the notion of creating a new, large-scale building complex within this historic shell. Controlling building movements and retaining construction tolerances between the new and existing structures was a key priority for the team.

Presets – the super-elevations factored in to account for the movements of the building during loading – were carefully considered, optimised and responsive solutions were incorporated into the design.

Long distance photograph capturing the Battersea Power Station development from across the Thames. Image: Brendan Bell
Creating a new, large-scale building complex within the historic shell of Battersea Power Station represented a significant challenge for Buro Happold’s experts on this iconic project. Image: Buro Happold.

Our structural engineers devised intelligent solutions for maximising space within the building using steel ground beams – known as comb caps – to support the existing foundations. These large-scale below ground structural elements take the loads created by the new support structures constructed above. The steel piled “comb caps” are based on a see-saw effect, with a compression pile and a tension pile creating the required stability.

For the duplex apartments, we developed a lean, efficient means to achieve an ambitious 11m cantilever over Control Room A in Switch House West. By placing an A-frame at the very top of the living space and inserting new pile foundations, the floorplate of the upper residential area could be maximised while meeting all heritage demands. We also devised a straightforward construction sequence and pre-setting strategy to ensure that agreed tolerances of the structure are met when the apartments are handed over.

Infographic detailing the design solution for Battersea Switch House West

The design and construction of a dramatic 11m cantilever A frame structure created an additional 20,000ft2 of prime residential lettable area. Image: Buro Happold.

Control Room B was situated within the middle of a steel frame. This necessitated formulating a means to cut and carve the floors above and below. Our engineering solution also incorporated a stabilising vertical concrete core and the installation of new foundations, all of which left the control room in an unspoiled condition.

The Boiler House was an enormous space (150m x 60m x 60m), and in order to optimise the space, a 15-storey superstructure was devised, which would cleverly maximise the floorplates of the residential spaces and offices above, while creating open spaces in the public-facing retail and entertainment areas below.

We designed a series of innovative “tree” structures in the boiler house that carry unprecedented loads while achieving a column free space. Image: Buro Happold.

In the North Atrium, load transfers were achieved with an innovative scheme that utilised transfer trusses, beams and “tree” structures, as part of the 24,000 tonnes of new steel infrastructure installed in the retrofitted building. This included the installation of a 27m, 62-tonne beam in the North Atrium. This mammoth beam, capable of taking 2,670 tonnes of load, ensured no columns were required to break up the visually impressive open space of the North Atrium. An innovative steel saddle and rockerplate solution was devised to ensure the loads are delivered safely down through the wash tower walls.

Two vast tree-shaped structures in the Boiler House each support 30m x 30m of office floorplate over eight storeys, while also serving an ornamental function within a column-free space. Buro Happold’s computational capability enabled us to take the architectural intent and translate it into impressive forms of monumental elegance. Overcoming problems presented by supporting these “trees” in the context of the power station’s complex subterranean infrastructure, we introduced piles measuring 2.4m x 60m.

Image: Buro Happold.