Spreading like wildfire: Why wooden skyscrapers are springing up across the world

Story highlights

  • New super strength products such as engineered bamboo are making timber a more popular building material
  • Experts say wooden buildings have a positive psychological effect on people

(CNN)Wood is being billed as the answer to creating greener cities -- lightweight and sustainable, it is even said to be more fire resistant than steel.

The newest addition to the timber trend is a proposed 19-storey structure that will be built in the Swedish city of Skelleftea.
    Designed by architecture firm White Arkitekter, it was the winning submission in a competition to design a cultural center and hotel in the Swedish city.
    The "Sida vid Sida" -- its name translated to side by side" -- submission was praised for paying tribute to the city's rich local timber industry, and the multiple design benefits attributed to wood as a building material.
    Once complete, the 19-storey structure is expected to become the tallest wooden building in the Nordic countries.

    Spreading like wildfire

    An explosion of timber towers, either built or proposed, has gripped the architecture world over the past five years, every one seemingly a recorder holder in some respect.
    In 2012, the 10-story, 104-feet-high Forte residential block was erected overlooking Melbourne's Victoria Harbour.
    It was the world's tallest timber building until The Treet in Central Bergen, Norway, stole that title in 2014, with an extra four stories.
    Oakwood Tower would be London's tallest wooden skyscraper.
    Last year, the Cube, a 109-feet-high apartment block in London's Shoreditch, became "the tallest cross-laminated timber structure in Europe," according to its developers.
    In Canada, work has begun on the descriptively named Tall Wood Building, which will provide student digs at the University of British Columbia.
    At 174 feet and 18 stories tall, it was set to be the world's tallest building, until the Oakwood Tower came along.
    The Oakwood Tower is a proposed joint project by PLP Architecture and Cambridge University's Department of Architecture. It's an experiment in pushing the frontiers of building with wood, and is part of a growing movement to build in timber.
    The 80-story tower, if given the green light for construction, will be made of timber -- making it London's first wooden skyscraper and the tallest wooden structure in the world.
    At 1,000 feet tall, it will only be overshadowed in London by The Shard.

    Branching out

    New types of ultra-strong timber are partly driving the trend.
    "There's a whole bunch of new materials made out of wood that are structurally able to build big buildings," says Dr. Michael Ramage, of the Center for Natural Material Innovation at Cambridge University.
    Cross-laminated timber, for example, sees thin layers of wood placed across one another at right angles, and laminated with fire-resistant glue to create a stronger weave.
    But it's bamboo -- a material that has been used in Asian construction for centuries -- that most interests Ramage.
    With a five-times higher growth rate than wood, but similar mechanical properties, there are 31.4 million hectares of bamboo worldwide, according to the Food and Agricultural Organization.
    "We're working on engineered bamboo," says Ramage. "We can take the walls of bamboo tubes, cut them up into rectangles and glue them into big slabs.
    "You get large pieces of what looks like lumber. But it's stronger than timber."
    Kevin Flanagan, a partner at PLP architects, adds that in the future he can imagine the industry genetically modifying wood to make it even more conducive to high-rise construction.

    London's burning?

    Obviously, when it comes to wooden buildings, there's one burning question.
    Are timber skyscrapers a fire hazard?
    Ramage says Oakwood Tower -- which will be an extension of the Barbican Center in Central London -- will exceed the fire standards of regular steel and concrete buildings.
    His center has been awarded £250,000 ($353,785) from the Engineering Physical Sciences Research Council in the UK to research timber construction techniques, such as fire proofing.
    "There is a huge perception problem," says Ramage. "Timber doesn't burn in the way the public imagines.
    "The great fires of London and Chicago were both sparked by very small pieces of wood. Very big pieces of wood are quite hard to set on fire -- they aren't kindling material."
    Wood, he says, burns predictably. Therefore, fire engineers can calculate how large a block of wood is needed to provide a protective layer to sustain a building for a certain period of time.
    "All buildings over a certain size need to have sprinklers and active fire suppression systems -- irrelevant of whether it's wood, concrete or steel," he adds.
    A series of blazes at Dubai skyscrapers in recent years have highlighted that it isn't just timber buildings at risk of catching fire.

    Does wood make us happier?

    According to Flanagan, wooden buildings have a positive psychological effect on people.
    "People tend to feel relaxed around wooden buildings," says Flanagan. "People associate wood with green spaces, they have an affinity to it. There would be a real benefit to introducing wooden structures to the cities where people live."
    In 2009, the Austrian Joanneum Research Institute compared four classrooms: two with timber flooring, ceilings and cupboards, and two fitted with linoleum floors, plasterboard walls and chipboard cupboards.
    Children working in the timber classrooms, researchers found, were more relaxed, displaying lower heart rates.

    Aren't we meant to be saving the rainforest?

    Yes. According to the World Wildlife Organization, up to 58,000 square miles of forest are lost each year -- that's equivalent to 48 football fields every minute.
    But Ramage explains that Oakwood Towers, if approved, would be built from "white wood" -- that is, crops grown over a 40-year-period specifically for construction purposes.
    "Russia has huge timber reserves, largely because we're finally using less paper," he explains.
    In fact, using wood could be more sustainable. Ramage says wood is, on average, four times lighter than concrete, so transporting it uses less energy.
    Furthermore, timber buildings are increasingly being assembled in a factory, and then craned into position and fixed together on site -- like an Ikea-style skyscraper that can "self-assemble".
    "This has huge time and financial savings implications," says Flanagan.

    Won't wood rot?

    From the magnificent Tudor timber arches of Westminster Hall in London to the wooden rooftops of the Forbidden City in Beijing, wood has been used to construct some of the world's most beautiful, iconic buildings.
    And they haven't fallen victim to rot.
    "We know from a very long history of building in wood it can last -- we have 600, 700-year-old buildings in the UK which are fine," says Ramage. "The one constant they have is that they have all been well looked after."