Environmentally friendly and quick to build, with an enduringly cosy aesthetic? No wonder timber towers are on the rise.
A timber age for architecture is dawning. At least, that’s the consensus among a smart bunch of designers and developers pioneering the use of this most ancient of building materials. As the process of taking timber from tree to tower dramatically improves, so too do our wooden buildings, becoming bigger, better and more sustainable than ever before.
“This is the future way to build cities,” says Marc Henri Maxit, engineer and one of the founders of Woa, as lengthy pieces of Austrian spruce swing through the air on spidery crane arms at a building site just outside Paris. “It’s clean, it’s more sustainable, it’s quicker – and you have much less noise.” It’s true that the screech of the angle grinder is mercifully absent at this soon-to-be social-housing block. Apart from a concrete-and-steel lift shaft, the structure is made entirely of wood. “It’s just like Lego,” says Maxit, looking at a colour-coded plan stating where each prefabricated panel should go.
While wood is an ancient material, large timber-built structures like this complex created for migrant workers are a relatively new innovation. Previously wood wasn’t considered strong enough to carry the weight of a large building. But this has changed with the development of cross-laminated timber (CLT) at the beginning of the century. “It behaves like concrete,” says Maxit as he runs his fingers over a vast piece of CLT, which will form an entire wall of the building. “It is layered and stuck together using fire-resistant glue like a kind of sandwich. Unlike wood, which is live, it doesn’t move – it’s as strong as steel.”
Even so, in the land of béton brut, it’s not easy championing wood. Wooden structures seem to initiate a “three little pigs” reaction. Will they rot? Burn? Or even get blown down? “When we think ‘wood’ we think ‘risk’ but we can prove that this is as safe as any building,” says Maxit. “It’s a question of changing perceptions. First we had to convince the professionals, now the public.”
In contrast to the painted concrete blocks that surround it, this construction site resembles an oversized treehouse or ski chalet. Yet Maxit insists that this is not about a cosmetic endeavour. For him, using wood is about providing solutions to the questions of sustainability, urban migration and quality of life. It’s also about cost. “We are post-crisis architects,” he says. “It costs more to build. Sustainable timber is here [in Europe], as are the forests – we should use them.”
Woa is currently working on Paris’s first timber skyscraper, co-designed by architect Vincent Lavergne. Maxit sees wooden structures as key to the future of expanding cities. “We can’t rebuild our cities but we can build a city on a city – wood is so light, it will be perfect for increasing density."
Albina Yard rises from its low-slung neighbourhood like a proud, if evolved, descendant of the surrounding century-old wooden bungalows. Built in 2016, the four-storey, wide-set office and retail project in Portland depends on timber with muscular structural beams, and warm interiors made from fir from the northwest’s forests.
Albina Yard has become something of a landmark in Portland. Its architect Thomas Robinson – whose practice, Lever, is based there – says about 1,000 people have toured it since inception. In part that interest arises from Portland’s new-found status as the US hotbed for big, ambitious developments in wood. Amid a building boom, the project is one of several notable path-breakers for “mass-timber” construction technologies, such as cross-lamination, which is strong enough for large-scale design.
Albina Yard was the first US building made from domestic CLT. The material inspires excitement in the Pacific Northwest, where the timber industry sees hope of revival in a material strong enough to replace structural steel and concrete. Oregon’s two major universities set up a joint-venture lab to research CLT and other new timber technologies.
“The project connected me to a part of Oregon I might not have known,” says Robinson. “We had to design with the specific attributes of the material in mind. That’s where you get creative.”
Beyond Albina Yard and Carbon12, a wooden condominium tower nearing completion, timber construction is rapidly gaining favour in Portland and beyond. Last year Japanese architect Kengo Kuma’s firm designed a prototype suburban residence for a developer called V, featuring both northwest and Japanese cedar. A Lever-designed wooden city-centre tower, Framework, will rise to 12 storeys when built later
this year. “The aesthetic effects of wood attracted us initially,” says Robinson. “But using it to create value makes the design even more meaningful.”
“In Norway we have this big tradition of building with wood yet we are making very few big wooden buildings,” says mdh Arkitekter partner Dagfinn Sagen. The architect is showing us Europe’s largest CLT project; it’s a development that has played a strong hand in bringing mass-timber building to Norway. The set of five nine-storey residential towers, a nursery and an upcoming library can be found in the Moholt student district of Trondheim.
On a crisp spring day, the pale silvery wood of the tower walls set them apart from the surrounding brick structures. Yet the buildings are in context with the northern Norwegian vernacular. The façades reference Nordic stave churches, with overlapping pine slats climbing up the exteriors, like the undulating shell of a pinecone.
Another bonus: when timber is felled and applied to a man-made structure, it still moves and changes to adapt to the climate. The shells of Molholt’s towers expand and contract, giving a sense of life to the building before the residents have even moved in. “For us it was important to have an honest expression in the timber detailing and the façade,” says MDH partner Minna Riska. “Making something as big as this in wood, we wanted it to show the material across everything, from the staircase to the elevator, which sits inside a timber frame.”
The harmony of these buildings, which form a sustainable urban hub, is motivating Trondheim to explore applying the material to further developments. While officials have recently held a conference to examine these possibilities, the Moholt project currently stands as the litmus test for whether mass-timber buildings, with their pleasing natural smell and texture, will have a greater role in Norwegian cities.“There are psychological challenges too,” says Sagen. “For example, the emergency exit staircases that climb up the side of each tower don’t need to be there. Their purpose is to reassure people that if the building were to catch fire, there’s another way out besides the interior stairs.”
But developers here are confident that overcoming the fear factor of working with wood won’t be difficult. Besides being proven to be safer in a fire situation than steel, CLT construction appeals to a consistent theme in Norway’s development: sustainability. Even though most of the wood used in the Moholt buildings came from Austria, the carbon emission reductions in its construction were off the chart.
“We are talking about a full package for co2 reduction,” says Moholt’s project manager Arvid Skjervik. He adds that the use of CLT in this project created a 56 per cent carbon reduction in construction emissions and says other elements, such as solar panelling and thermal heating, have set high sustainability benchmarks. “When it comes to building fuel-efficient neighbourhoods, with environmental goals, projects like this enable governments to practice what they preach.”
At MDH’s Oslo office, the team joke that they’ve had more interest from media and other architects trying to emulate their success than CLT-based commissions. However, they’re currently hammering away at a few proposals, including a timber solution for a new set of subway stations for the city.
“We’ve lit the fire on the topic of how to make big timber structures possible in Norway,” says Sagen. “Now there’s even a discussion on whether the new government headquarters in Oslo should also be made of timber. The politicians are the ones leading the conversation in fact, as it would boost Norway’s timber industry and show this new face of the nation’s architecture.”
For anyone who has ever wondered how Japan – a country with earthquakes, typhoons, ragingly humid summers and bone-dry winters – manages to have some of the oldest wooden buildings in the world, Kenzo Akao has the answers. Director of Takenaka Carpentry Tools Museum and an architect of 50 years, he can explain exactly why buildings such as Horyuji Temple in Nara, built in the 7th century, are still standing in spite of everything nature has throw at them.
“In those days the carpenters did everything: they went to the mountains, they chose the wood,” he says. “They cut down the trees, took the wood to the site and then worked on the building. The trees grew up close to where construction was happening so they were suited to the climate. And, of course, the carpenters knew where best to place each piece of wood.”
What Kenzo Akao doesn’t know about wood construction isn’t worth knowing. His museum, a beautiful repository of timber tools a hair’s breadth from Kobe’s bullet train station, started as a madcap project 30 years ago. The then president of Takenaka Corporation, a construction giant whose roots go back to 1610 when it was a carpentry company, realised that the tools that had been so crucial to the development of the most sophisticated wood-building techniques in the world were in danger of disappearing. One small problem was that the company didn’t have a collection. So every Takenaka branch office was put on alert and the great tool hunt began.
In five years the collection had reached 10,000 pieces and today the museum has 33,000, a comprehensive array of nokogiri (saws), nomi (chisels) and kanna (planes). “Many were in bad condition when they arrived,” he says. “We had to bring some back to life. If you see the state of a tool you can tell how good the carpenter was – it takes skill and a lot of time even to sharpen one of these tools.”
The museum relocated to a new building next to Shin-Kobe Station three years ago. Yoshino cedar was used for the ceilings and frames, white oak for the floors and chestnut for the entrance door. It tells the history of wooden building in Japan, from temples to teahouses, and has fine examples of both, including a life-size recreation by highly skilled miyadaiku (temple carpenters) of a 1,300 year-old interlocking pillar from a temple in Nara.
And while the museum is largely a celebration of the past, its remit is also to inspire Japan’s next generation of carpenters via an outreach programme for schools. “Many children have no idea how a house is built – everything is done by machine now so they’ve never seen these tools before,” says Akao. “We’re trying to teach them the spirit of monozukuri, of craftsmanship.”
Vancouver is rising as a world capital for tall timber buildings. British Columbia’s forests are abundant with Boreal wood perfect for the province’s trailblazing timber towers, such as Tallwood House, the world’s tallest.
Tallwood House at the University of British Columbia opened last year. It draws on clt, which is perfect for floors, walls and cores; it’s also a key loadbearing material.
Tallwood House will be dwarfed by Shigeru Ban’s hybrid timber Terrace House in 2020. Its posts and beams are milled to millimetre precision and prefabricated close to harvest time in the Kootenays.
The pure-timber buildings of the future may be light, sustainable and naturally fire-resistant but building codes will take a while to catch up. In a fire the charring properties of wood actually become a fire-retardant.
When the prefabricated posts and beams of Terrace House arrive on site there’s no need for jackhammers and grinders. They can be quickly fitted to embedded steel connectors in the concrete core.
With its timber components producing about a fifth of the carbon emissions of concrete equivalents, Terrace House developers hope that it will point towards a more sustainable city skyline.