The 9m-high Hy-Pavilion has been variously described as resembling four interlocking pairs of enormous wooden scissors and an inverted, inside-out teepee. Whichever way you look at it, it certainly is eye-catching. Which is one of the reasons TRADA has chosen to make it the central feature of its stand at Timber Expo, the new UK timber industry exhibition this September.

The striking structure is an exercise in timber engineering, devised for London’s Festival of Architecture by Tim Lucas, partner at consultant structural engineers Price & Myers. The company has quite a portfolio of wood-based buildings under its belt and is one of the UK’s few exponents of engineering structures that use sheet materials as a stressed skin, a prime example being the plywood and steel pod-style penthouses erected on top of Bradford’s Lister Mills.

Ease of use
For the festival, after considering using steel frame, Lucas decided to use the opportunity simultaneously to demonstrate what Price & Myers’ had learned about wood’s creative possibilities and potential ease of use.

“I wanted to create a pavilion that was made out of a very basic element, a straight line, put together in an interesting way so that it could be elegant and exciting, but simple to make and build,” he said. “We always try to do something for the festival, but previously provided architects models. Our aim was also to do a full-scale structure for a similar cost.”
The form Lucas eventually struck on to achieve the desired meld of simplicity and stop and stare looks was a hyperbolic paraboloid. This creates almost a trompe l’oeil effect by crossing a series of straight elements to give the impression of curves. And in the Pavilion this special effect is accentuated by intersecting two hyperbolic paraboloids in a single structure.

To get the effect just right, Lucas worked on a series of computer models, then created 20:1 and 1:5 physical prototypes. The process took around four months.

Kerto LVL
The design and plans for the pavilion to be demountable and trucked around the country from event to event, demanded a core material that combined strength with lightness. Consequently Lucas opted for Finnforest’s Kerto brand laminated veneer lumber, a material built up like plywood from multiple thin layers of softwood bonded together under pressure. “We like Kerto,” said Lucas. “It’s efficient, strong and makes good use of the tree.”

The Pavilion used eight Kerto beams. These were originally 12m long, 400mm wide and 75mm thick, but were cut to 10m and tapered at the ends, with the offcuts saved to make the benches inside the structure. Steel connector plates are bolted to the pointed ends of the timber together with an articulated joint. Each beam then connects to another at the tip, and a second at the base and is also attached with a pivoting bolt at an angle of 55° to a third to form an X.

A series of steel cables and 56 bungee ropes also link the Kerto, completing the hyperbolic paraboloid and giving the whole structure added tension and strength.

The other element is a 34m² canvas panel which forms a roof about halfway up, connecting to the timber frame with a series of rachets and pulleys so it unfurls as the pavilion is erected.

The Pavilion comprises eight Kerto beams, steel cables and 56 bungee ropes

Easy erection
The whole thing weighs around 700kg but, because of the way it’s hinged and pivoted, it can be put up, from lying flat with one hyper parabolic frame inside the other, using just a couple of Tirfor hand winches. Lucas likens the process to unfolding a deckchair.

“It’s very simple and the fact it doesn’t require a crane is a real advantage,” he said. “We first put it up in public in London’s Store Street under some trees, which wouldn’t have been feasible if we’d needed a crane.”

For added ease of transport the 10m beams are cut in two and joined on site with further connector plates.

Finally the whole pavilion is bolted to four steel trays, each weighed down with concrete slabs. And the structure can be delivered to site and erected, says Price & Myers, in less than a day.

TRADA first saw the pavilion in London and thought it would make the ideal centrepiece for its stand at Timber Expo, which it is co-organising. It will provide a 360° stage for talks and presentations on new timber products and TRADA’s range of activities and services, including its Q-Mark quality assurance scheme.

“We wanted something to grab visitors’ attention and make a visual statement, which is what the pavilion certainly does,” said TRADA marketing manager Rupert Scott. “At the same time, it’s a clever structure that also says much about what is possible with timber. That’s exactly what Timber Expo is intended to convey. It provides the perfect platform for TRADA and the event as a whole to deliver the timber message to specifiers.”

Demountable
The Hy-Pavilion’s demountability was another attraction. “We’ve focused on timber’s suitability for demountable buildings and produced a book on the subject,” said Scott. “We think it will be an increasingly significant area, particularly with events, notably the 2012 Olympics, looking at legacy and recycling or reusing structures afterwards, rather than just trashing them.”

Meanwhile, Lucas is considering how the Hy-Pavilion can be developed. “A group of them linked together to form a bigger structure might work,” he said. “It also has a very celebratory air. It would look good with pennants fluttering from the points and we have half an idea to build a tower out of them mounted one on top of the other!”

A 34m2 canvas forms a roof

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