Back on the Grid

“Everything is landscape,” says the architect Glenn Howells, looking at the Savill Garden Visitor Centre, in London’s Windsor Great Park, on the building’s opening day in June. A slim roof composed of three leaflike valleys sits aloft a timber structure and, from certain angles, almost disappears into the grounds behind it. Glenn Howells Architects designed the unusual building for the Crown Estate, the conservative body that manages all of the Royal Family’s lands. Built mostly from wood, the gateway to the gardens reflects its setting as well as serving another role: propelling a particular strand of lightweight timber engineering, pioneered by German visionary Frei Otto, further along its essentially infant path.

The underside of the roof—also visible from outside through the plate-glass windows—features the unmistakable diamonds of a grid shell, a lattice of hundreds of crisscrossing timber laths that combine to share the structure’s distributed load and create large interior spans. It’s a fusion of high-tech computer modeling and low-tech craftsmanship that is unusual in a world governed by the economics of high-speed design and construction. Howells and his team needed nearly five years to complete the $9.5 million project. “We explained a number of different solutions, took a year developing the idea for planning, and then started felling trees,” the architect explains. “It’s a form of slow building.”

Timber building, out in the cold in Britain for many years, has been enjoying an architectural resurgence since the completion of the award-winning Weald & Downland Museum grid shell by Edward Cullinan Architects in 2001. This remarkable building introduced the technique to Britain and turned many architectural heads, being only the second permanent, large-scale wood grid shell built anywhere since Otto’s Mannheim Multihall was completed in 1974. The Multihall was fiendishly difficult to engineer, and because thousands of the laths fractured while it was going up, few thought the idea would be repeated.

Believing that the Weald & Downland Museum embodied the kind of iconic environmental architecture the Crown Estate was seeking, Howells linked up with the building’s veteran engineers, Buro Happold and Green Oak Carpentry Company, to enter the Savill Garden competition. “We wanted, shall we say, a contemporary building,” Crown Estates deputy ranger Philip Everett says. In fact the limited competition for Savill Garden—a few miles from Windsor Castle—stipulated an eye-catching building with a core material of timber harvested from Windsor Great Park’s own ­sustainably managed woodland. The three partners developed a radical sinusoidal computer-modeled design, which Howells helped the judging committee understand by taking them to Cullinan’s recently opened grid shell. “I don’t think Savill Garden would have happened without Weald & Downland already being there,” says Richard Harris, head of wood engineering at Buro Happold, a company that, not coincidentally, was founded by engineers who worked with Otto on the Mannheim building.

The opening of the Savill building pushes grid shells, and the timber engineering tradition they spring from, further into the mainstream. While carpenters and their craftwork remain essential to the process of building a grid shell, Howells acknowledges the role technology has played in making them more viable. “Without computer-modeling techniques, it wouldn’t have been possible to get the fineness and efficiency of the design without redundancy,” he says. “The whole structure becomes demystified.”

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