Design process
For many years the Downland Museum's building conservation workshop and timber store were inadequate. Acknowledging this, a brief for a more suitable building aimed for an innovative design that would complement the existing historic site and the topography of the wider Weald and Downland region. Environmental control was also necessary, and needed to be responsive to the physical working demands of the museum, especially for the storage of fragile artefacts.
In response to this challenge, Edward Cullinan Architects won the tender with their gridshell design. Funding came largely from the Heritage Lottery Fund (HLF), which gave a grant of £70 000 to develop the project. A final bid was submitted to the HLF in late 1998, resulting in a grant of £1.2 million. The museum raised an additional £750 000 during the design and construction, bringing the total project budget to just under £2 million, equating to a cost of £1100 psqm.
The gridshell structure was a technical challenge for the architects, engineers and carpenters. Previously, gridshells have been built flat on the ground and pushed up into shape with many fractures. A new technique was developed at Weald and Downland, using a flat gridmat of two latticed layers of 36 metre long oak laths, 35 x 50mm in section, constructed on top of 7.5m high scaffolding. These laths were made by connecting six, six metre long, laths with scarf joints. The scaffolding was then lowered at predetermined points by a few centimetres each day, slowly bending the mat into the desired gridshell shape, with carpenters fixing any of the joints that broke (of the 10,000 joints, only about 145 did). Adjustments were made by eye, referring to the computer model, until the framework was fixed into place three months after the lowering process had begun. Cladding, roofing and installation of ventilation systems were completed over the next nine months, with the building opening to the public in 2002.
To reduce loads on water and power supplies, the building and site systems took advantage of natural features such as earth mass heating, with heat sourced from digging into the ground, and rainwater collection.
The construction of the gridshell with so many design innovations meant that this project was not simple. Active involvement and consultation on detail and innovation between Edward Cullinan Architects, Buro Happold (engineers), Boxall Sayer Ltd (quantity surveyors), and The Green Oak Carpentry Company Ltd (technical carpenters), at the beginning of the process was exemplary and critical to the success of the complex design and construction. The carpenters' expertise as boat builders is credited as helping them visualise the curves of the roof.
This exchange of ideas and expertise early in the process helped to develop the design and provide clear milestones to be achieved as well as providing a clarity of vision throughout the process; translating this innovative vision into a successful workable reality.
