Support free timber roofs

From schools to concert halls, lecture theatres to train stations, support free timber roofs are springing up all over the place. TiC visits a school in Kent to get the low-down.

AS YOU pass through the doors of Marlowe Academy, you are assaulted by a grand influx of light, space and warmth. It is not too far reaching for you to think you have entered a concert hall or a gallery as you have a school, as you begin to appreciate leasons being taught under the sky-filled surroundings.

The Marlowe Academy at Ramsgate in Kent, was designed by architects British Design Partnership (BDP) and was awarded a Royal Institute of British Architects’(RIBA) National prize in June. The Academy also won the Structured Category in this year’s Wood Awards.

By far the most spectacular structure at the academy is the timber gridshell roof that vaults a full 20m across the acadmey, allowing daylight to stream in through glazing in the centre of the roof, injecting a liveliness into even the most dormant of adolescent.

Technically, the roof employs a design developed and patened by American architect Buckminster Fuller in the 1920s, known simply as a geodesic dome – a spherical structure based on a network of struts arranged on great circles (geodesics) lying on the surface of a sphere.

Blue-sky thinking

“The design is certainly not new,” explains Gordon Cowley managing director of Cowley Timberwork, one of the structural engineers on the project. “The structural efficiency of the form has been going for a long time and is used in all sorts of ways around the world.”

Some of the largest structures in the world have developed out of Fuller’s proposal. In the UK this is represented by the Eden Project in Cornwall and the new tessellated roof of the Great Court of the British Museum, designed by Foster and Partners in 2000.

“The advantage is more from the shape of the structure than the way it is satisfied,” explains Cowley. “Simply having it as a hemisphere or an arch is so much more efficient than a straight beam. It works like an egg does. It is the shape that gives it its robustness.”

From an engineering perspective, geodesic domes are far superior to traditional right-angle post-and-beam constructions, explains Cowley. Traditional constructions are a less efficient use of materials, are far heavier, less stable and rely on gravity to stand up. Cowley offers his own interpretation: “I think the simplest explanation I can offer is that the design is formed between taking the shortest line between points on a sphere,” he says.

From an aesthetic principle, the design offered a number of graceful aspects for Marlowe, explains Cowley. “The shell looks pretty basic structurally,” he says, “and makes it totally free of columns and support.”

A space free of structural support was crucial to Marlowe. The space allows the pupil and staff population to meet together in one place for whole school assemblies. The award citation for the RIBA prize made this a huge consideration for its nomination: “The new Academy replaces the existing failing Ramsgate School. The traditional corridor with its problem of congestion, inefficiency and bullying has been replaced by a series of lively spaces with real educational potential.”

Creating a Masterpiece

A number of ingredients combine to strengthen the shell. Firstly, the ribs and the sheathing above them are made of Kerto laminated veneer lumber, Finnforest’s thick and variation on plywood. Cowley explains that glulam had also been considered. “The Kerto is quite a bit stronger than glulam and it was more efficient for the arching shape needed for Marlowe’s roof. The deck Kerto planks were bent around the curve and shared the load with the ribs.” he says.

The discreet connections at the nodes where the ribs meet comprise special steel rings with angled spurs that are bolted into the ends of the ribs. They were designed and patented by Cowley and were The discreet connections at the nodes where the ribs meet comprise special steel rings with angled spurs that are bolted into the ends of the ribs. They were designed and patented by Cowley and were used for Napier University in Edinburgh.

The discreet connections at the nodes where the ribs meet comprise special steel rings with angled spurs that are bolted into the ends of the ribs. They were designed and patented by Cowley and were used for Napier University in Edinburgh.

Cowley said the geodesic design in timber offered Napier welcome relief to some early problems. “The contractor went into liquidation half way through and the client thought they’d be forced to carry on in a different way and went shopping to do it in steel,” he says. “They found that the depth of structure needed with steel would have cost them more seats in the auditorium and they wouldn’t of had the same space available to them.”

The lecture theatre aspect seems to be gaining momentum, Cowley explains. “Of the geodesics Napier University was the first one we did followed by the refurbishment of the dilapidated 50-year-old Kingsdale secondary school in a London,” he says.

In 2004, Kingsdale went from being a condemned school in the “special measures” category to being one of the UK’s 20 most improved schools.

Cowley admits that the UK’s mindset of adopting timber into its project studies has picked up serious speed over the last ten years, but still it lags behind our European counterparts. Cowley is particularly appreciative of timber use in Germany. “A lot of the design seems to have hailed from Germany. It is a fantastic user of structural timber and we can continue to learn from them,” he says. “By square meter they are still way ahead of us in terms of timber use.”

Cowley formed the company more than 25 years’ ago but says today it is seeing an increase in demand for all timber. And with the geodesic designs springing up in all types of structures from lecture halls to multipurpose arenas, who’d bet against seeing more of a roof structure that gets stronger as it gets larger?