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Stronger than concrete? Why this new material could define our age

Updated 25th November 2016
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Stronger than concrete? Why this new material could define our age
If the 19th century belonged to iron and steel and the 20th century belonged to concrete, could timber be the building material of our age?
That is the question posed by architect Alison Brooks' "The Smile," which was on display at the Chelsea College of Art and Design as part of this year's London Design Festival.
Constructed out of tulipwood, "The Smile" is a 34-meter long, 3.5-meter high (111.5 feet by 11.5 feet) rectangular tube that curves at both ends into a huge Cheshire cat grin. Viewers could wander through the hollowed interior, while holes in the walls cast light patterns across the floor.
It is the most complex structure ever to be made out of cross-laminated timber (CLT) and, as such, was one of the most exciting installations at the UK's largest design festival.
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"It's going to open up a whole new world of possibility," says Brooks. "It reveals the possibility of buildings being completely fabricated in wood."

The secret of strong wood

A collaboration with Arup and the American Hardwood Export Council, "The Smile" is an experimental building -- part pavilion, part sculpture -- designed to showcase the structural and spatial potential of a material that could transform the way architects and engineers approach timber construction.
"I think the potential of hardwood is yet to be discovered, it's the next step," Brooks says.
Tulipwood CLT is light but naturally strong, allowing the two ends of "The Smile" to soar into the sky.
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"I think what's kind of amazing is how thin the walls and floor are," she adds. "Tulipwood has a tight grain and a really rich variation in color. It has a lot of warmth."
While steel and concrete have been used as structural materials in buildings for decades or even centuries, the use of timber has long been hampered by the fact that it did not come in panels large enough to be used in a building's fabric or structure, for instance in the core.
This issue has been resolved by the development of CLT.
"CLT is a really clever way of making very large panels from small trees," says Andrew Lawrence, timber specialist at Arup.
This is achieved by gluing planks together in layers. The planks in each layer are turned at right angles to the next in a crisscross effect.
"The Smile" is made of just 12 panels manufactured by German CLT pioneers Zublin-Timber, and held together by screws.
The largest panel is 14 meters (46 feet) long and 4.5 meters (15 feet) wide, a size that can compete with precast concrete.

A sustainable future

Timber has other properties that make it attractive to engineers and architects. CLT lends itself to prefabrication, explains Lawrence, because it can be cut precisely in a factory and is easily assembled on site.
"A building of CLT is like a giant piece of flat-pack furniture. That's why the construction industry has fallen in love with it, because it's so easy to transport, crane and assemble," Lawrence says.
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Though CLT made from softwood such as spruce has been in use for some time, the full potential of hardwood has not been explored until now.
1/19Wooden skyscrapers
This floating wooden pavilion is the Pavillion of Reflections in Zurich. It was revealed as part of Manifesta, an annual contemporary art biennial. Credit: Wolfgang Traeger
David Venables, European director of the American Hardwood Export Council, believes hardwood CLT could also help buildings be more sustainable.
"Over one billion cubic meters of this tulipwood material is standing in American forests right now," he says. "If we want to be sustainable we have to use all the material that nature provides."
"Timber construction is absolutely the future," he adds. "'The Smile' is the beginning of something. This isn't the end of the journey."
"The Smile" was on display through October 12 at Rootstein Hopkins Parade Ground, Chelsea College of Art and Design in London
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