Japan plans to take timber high-rise construction to new heights

A Japanese company has revealed plans to build a 350m-high tower made predominantly of timber, which, if ever built, would dwarf the wooden structures currently being constructed or contemplated.

In recent years a global competition has developed to build the world’s tallest timber tower, with Norway, Canada, Austria and Australia entering the race – and arguing over whether it is cheating to including non-timber structural elements.

But Sumitomo Forestry’s vision for its mixed-used “W350” tower would be three times higher than its nearest rival, 40m higher than London’s Shard and the 34th highest building in the world.

Sumitomo Forestry is the timber and housing arm of the Sumitomo keiretsu, a group of autonomous companies organised around the Sumitomo bank. It is planning to complete its W350 project in 2041 to mark the 350th anniversary of the company.

The W350 in cherry blossom time. (Sumitomo Forestry)

The structure would be a hybrid, made up of 90% wood, including all the internal elements. It would use a “braced tube” structure, with the timber element forming a hollow rectangle stiffened by a steel frame and diagonal struts.

The delight element would be enhanced by filling much of the tower with live plants, and giving apartments generous balcony space to enjoy sunshine filtering through the foliage.

Altogether, the mixed-use building will contain 185,000 cu m of wood, and would cost something like $5.5bn, about twice the price for a similar tower built with conventional materials, however the company says it hopes that costs will fall as technology improves.

And wood is a fast developing area for materials scientists – as GCR reported last week, scientists at the University of Maryland have discovered an inexpensive treatment that can increase the strength of wood by a factor of 10 while solving the all-important problem of dimensional stability.

The ultimate aim is to create a city of wooden buildings, narrowing the gap between cities and nature

The hope is that the increased use of wood and other natural materials will help to make cities a friendlier environment for humans and other animals.

“Under this concept, greenery on the earth will contribute to buildings and cities, making over cities as forests,” the company says.

“Buildings that are full of greenery will form a network that is linked to the biosphere of living creatures such as wild birds and insects, contributing to the biodiversity of cities.”

The ultimate aim, the company said, is to create an environment-friendly city of high-rise buildings made of wood that also helps to “transform the town into a forest”.

The company is working with Tokyo architect Nikken Sekkei on the design.

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