>> This is the world's tallest wooden building 14 storeys high, almost 53 meters tall. And made using sustainable forests, it's called the tree and looks out of the Norwegian city of Bergen. Alister Doyle Reuters environment correspondent got up on to the roof.>> It's more environmentally friendly, you store away carbon dioxide in wood, less CO2 is produced.
And so perhaps when countries were signed up two years ago, a year and a half ago, for the Paris agreement on climate change, this will mean a big push towards wooden buildings. Which of course has been the material for buildings across places like Norway for hundreds of years for smaller buildings.
Now they're reaching to the skies.>> Concrete makers, though, dispute the idea that timber is greener. They insist deforestation cause even more CO2 emissions. Up on the roof, concrete slabs are used to reduce movement. The weights stops the plyscraper from swaying. But the first question on everyone's lips, is this a fire hazard?
>> The architects say, that actually fire is not so much of an issue because the wood burns very slowly. Such thick beams of wood burn very slowly like a log on the fire. It retains some of it's strength. The building doesn't sway more than a normal building. They say it's a nicer place to live, it's more natural.
There's a more natural smell to the place. All the flats are sold here.>> Another similar and slightly taller structure is being erected in Canada. Australia has one too and plans are afoot in Austria and London. The structures are more expensive to build but prices may fall as the industry matures.
While they maybe only a marginal threat to concrete and steel at the stage, those behind the wooden buildings argue it's time for timber, as buildings like this put their roots at the city's skyline.