New "world's tallest" timber towers sprout up quite regularly nowadays, but Japanese lumber and housing firm Sumitomo Forestry could smash all current records if its ambitious plan to build a supertall timber skyscraper in Tokyo is realized. Rising to an impressive 350 m (1,148 ft)-tall, the tower would be a real feat of wooden construction.

If it does end up being built, the skyscraper, dubbed W350, will comprise 455,000 sq m (4,897,579 sq ft) of floorspace, spread over 70 floors. This will be split between retail, residences, office space and hotels. The roof will be topped by a green space and the facade will be dotted with greenery too.

According to Sumitomo Forestry, the building will be made mostly from wooden materials, with some steel structural support to ensure it can withstand earthquakes and high winds.

"The planned structure is a hybrid wood and steel structure made from 90 percent wooden materials," says the firm. "It will use a braced tube structure in which steel frame vibration control braces (diagonal braces) are positioned inside a column and beam structure, made from a combination of wood and steel.

The outermost side is designed with balconies that continue around all four sides of the building. The balcony part gives the high-rise building a space in which people can enjoy fresh outside air, rich natural elements and sunshine filtering through foliage. The greenery connects from the ground to the top floors through the balcony part, and it offers a view of biodiversity in an urban setting."

There's one major wrinkle, though. According to Sumitomo Forestry, the total construction cost of the W350 is estimated at an eye-watering 600 billion Yen (around US$5.6 billion). The project isn't planned until 2041, which will be Sumitomo's 350th birthday (hence the tower's name and symbolic height), by which time the firm hopes that technological advances in timber construction and further research will help lower costs.

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