Acoustic Shells

Sited in a sunken garden beside the beach in Littlehampton, West Sussex, UK, these ‘Acoustic Shells’ act as a stage and shelter for the local community. Prompted by a desire to reinvigorate Littlehampton with its gentility of the early 20th century, the shells materially enhance the public open space of the adjacent greensward and satisfy an essential social need that is not provided elsewhere in the area.
The concept for the shells is derived from the notion of a traditional bandstand; following the industrial Revolution and worsening conditions in urban areas, bandstands were conceived as a response by local authorities to an increased need for green open spaces where the general public could relax.
Following the first bandstand in Britain in the Royal Horticultural Society Gardens in South Kensington in 1861, bandstands became hugely popular, and were subsequently installed in parks across the country. Competing with new medias in the 20thC; cinema and television, bandstands lost their appeal, and fell into disuse. However, the new world of social media has further democratised the production and distribution of music. No longer the preserve of elite musicians, popular music is again made by anyone, and played anywhere, whether this is online, or in public. The Acoustic Shells are a response to this context, bringing back an old ideal, an architecture that can represent ‘sound’, and the people that made it.
One shell faces the town and forms the principal bandstand. The acoustic design of the interior creates a reflective surface to project the sound of the performers to the audience in the sunken garden. The other shell faces the beach and forms a more intimate structure as a shelter for listening to the sound of the sea or for buskers to perform facing the promenade.
The £100k budget for the Acoustic Shells prohibited the form of a more traditional bandstand; a large elevated platform, open sides, and an acoustically reflective soffit, and roof. We chose to unify the architectural components of the brief; floor, walls, structure, roof, into a single entity that would reduce materials, complexity and cost. A traditional timber structure was ruled out due to the harsh marine environment and the threat of anti-social behaviour such as graffiti and arson. It was decided that a robust material was required that could withstand all possible eventualities. Concrete was chosen as a material that could be dense enough to meet an acoustic brief and be robust enough to be a match for the environmental conditions.
An ‘all concrete’ structure had its own problems and would have to use innovative construction techniques to limit the wastage inherent in shuttering and forming processes. Research was undertaken in the development of thin, ‘shell’ structures. These can be self- supporting, so have structure integrated into the form of the shell. The most efficient technique that would suit was that of sprayed concrete. With care, this process can produce the complexity required by the Acoustic Shells project, and be carried out in a short time frame, thus reducing the site costs further.
The project was built in two distinct stages: The construction of the shells by Shotcrete, the specialist Sprayed Concrete contractor; followed by the integration into the landscaping which was by Landbuild.
The development of the scheme in 3 dimensions was very complex, and involved considerable input from the contractor. After having developed the form of the building in specialist software, a digital model of the scheme was handed to the Shotcrete Group
to drive the development the form. Following the ordering and delivery of the reinforcement bars, a grid of scaffolding 1m x 1m x 1m was set up on the site. A corresponding digital version was set up in the architect’s office. Points were taken on the digital model where the form of the shells touched the grid. These were then marked on the scaffold. These points were then checked by digital survey, and sent back to the model in the office for review. Once all parties were content with the spatial co-ordinates, the reinforcement bar mesh could be assembled within the constraints of the marked scaffold, with the confidence that the form of the shells will confirm exactly to the shape and specification of the digital version.
Following the reinforcement bar assembly, an expanded metal mesh was threaded into the structure. This acted as ‘lost shuttering’ and enabled the spraying process to take place from both sides. The thickness of the shell was on average 100mm, with the leading edge thickening to 150mm for structural stability.
Once sprayed, the structure was hand finished with metal trowels, creating a perfectly smooth finish. This was then painted and given an anti-graffiti seal.

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