Artists' materials Snell Associates' glass pavilion with a fabric roof forms both entrance and gallery to an art college
The fabric roof of the new Foyer Gallery, designed by Snell Associates for the Surrey Institute of Art and Design at Farnham, Surrey, produces a quality of light conducive to viewing works of art. The gallery is the main entrance to the college and the innovative roof form also serves to attract passers-by. It demonstrates the college's commitment to modern design in its contrast with the slightly worn 1960s college buildings behind.
The gallery/entrance foyer is designed to be visually and physically accessible, so as to attract and engage the local community. A gentle ramp gives easy access for wheelchairs. The fabric roof extends to cover part of the ramp, creating an area with possibilities as an outside exhibition space or sculpture terrace. At the rear, just beyond the gallery's reception desk in the original building, is the college's main exhibition space.
The roof and two frameless glass walls allow the open-plan space to be filled with light. One glass wall contains the main entrance and is fitted with automatically bi-parting sliding glass doors. The other glass wall looks out over woodland. The roof and walls are supported by a lightweight steel framework set on a raised concrete floor slab. The roof comprises a series of doubly curved 50mm diameter steel arched bars which support the fabric roof. The fabric works compositely with the steel arches to give lateral restraint, allowing the sizes of the steel members to be kept to a minimum. Part of this composite action is generated by friction between the stressed fabric and the steelwork. The main action is achieved by carefully positioned Velcro straps attached to the fabric. Structurally the fabric and arches behave like an umbrella, unlike conventional fabric roofs. This interaction is an innovative form of construction; in order to understand the behaviour of the members, in terms of deflection and stresses, a 3D non-linear model of steelwork and fabric was analysed using Buro Happold's tensyl software.
In warmer weather, air can be cooled by being passed beneath the slab before entering the building through floor grilles. Electrically controlled openings at roof level remove exhaust air. In cooler conditions the ventilation path is closed and the space is heated with an underfloor heating system.