Timber, in architecture, is undergoing a bit of a renaissance. It's not all glacial glass and steel out there, you know. But normally it is used superficially, or as a basic framing system. Here, it is turned into something extraordinary and delightful. When you walk into the Gridshell, what strikes you is the beauty of pure, unadorned structure, expressed surprisingly delicately in what is a rough, tough material: green oak. It succeeds in being both ancient and modern, but that is hardly a surprise. A brick can pull the same stunt. Such materials are interesting only because of the way they are used. Here, you can instantly appreciate the ingenuity that has gone into the timber structure. As very few buildings ever manage, this one shows you exactly how it works. It is high-tech in the true sense, as opposed to workaday industrial chic.

It creaks gently and almost constantly as it warms and cools in the sun and wind. It is this that makes you feel that it is living and breathing, that also gives it the feel of the hull of a wooden ship. Romantically, you would like to think that this is the result of all those timbers flexing. The truth is more prosaic: it is the high-level polycarbonate glazing, providing the necessary daylight into the workshop, that makes the lively noise.

The building resulted from a triple alliance of skills - Cullinan's as architects, Buro Happold as structural engineers, and Andrew Holloway of the forward-thinking Green Oak Carpentry Company. Happold's are specialists in lightweight structure, who made the Millennium Dome work. The architects - Ted Cullinan, his partner Robin Nicholson, and Steve Johnson - never saw this as being just a bit of smartly structured woodwork. Too many such shell buildings look unfinished on the outside, often being covered with a horrible plastic skin like elephant hide. Cullinan was determined to avoid the elephant-hide look, hence his deployment of solid (cedar) and clear (polycarbonate) cladding. Architectural deftness is apparent in the purposefully outward-leaning arched portals at either end, in shrewd proportioning, and in the unexpected but wholly successful addition of a snaking flat ribbon roof.