The University of Exeter’s Forum building provides a stunning £48 million centrepiece for the hilly Streatham Campus. It connects the Library and the Great Hall, unifying two vital centres which were once separated by a steep slope. The Forum Project encompasses new and refurbished structures enclosed under a stunning gridshell roof comprising a matrix of timber members joined by a series of galvanized steel nodes.
The Forum was a result of a two-stage international design competition. The starting point for the architects was the undulating landscape of the campus, with the landscaped piazzas responding to the contours of the hillside setting. A new entrance building at the north western end of the piazza provides a reception area for the University and Great Hall. The curving roof form of the entrance building rises one storey, and then falls to trace the northern elevation of the Great Hall before merging with the Forum project. Beneath the roof and behind the glass facades which now encapsulate the space between the existing buildings, the Forum is an airy, galleried hall. The upper level gives access to the Great Hall, Student Guild and a new suite of learning labs and seminar spaces designed for discussion and open debate.
The Forum’s roof encloses 3,500m² of column-free floor area making it one of the largest timber roofs of its kind. Beneath the roof’s copper cladding, lies an innovative hybrid timber structure which emulates the traditionally all-steel construction of a gridshell roof, weaving between the existing buildings of the campus. Wilkinson Eyre developed software in-house to enable the standardisation of parts for the ambitious roof design, minimising variants, and therefore cost, despite the complex geometry. The triangular cells of the grid are connected by galvanized steel nodes and are either clad in copper, with oak-slatted acoustic baffling on the interior surface, or filled with ETFE (ethyl tetra fluoro ethylene) pillows, which flood the interior spaces with natural light.
The complex, undulating roof form is made possible by the galvanized node where all of the members’ rotation and changes in angle occur in order to tessellate the triangular panels across the surface. Of the 150 nodes, around 20% are located outside the building, but even those internally were exposed to the elements during the erection and were subjected to the usual risks of damage during transportation and construction. This protective galvanized coating philosophy was also then carried through to the flitch plates that were used for 10% of the beams in the most highly loaded areas and the plates used in the bolted connections for the secondary to primary beam.
Architect: Wilkinson Eyre
Image: Hufton + Crow