A skyscraper is set to become the tallest timber structure in the world. The 350 meter (1,148ft), 70-floor construction will tower over Japan’s capital as a lighthouse of environmentally-friendly building. However, construction isn’t scheduled to start until 2041.

How the skyscraper will look like. Image credits: Sumitomo.

Architects have become more and more passionate about timber constructions, and Tokyo has more than its fair share of wood structures. In fact, a law passed in 2010 mandates that all public buildings of three stories or fewer need to be built primarily from wood — but skyscrapers are a completely different story.

The new project belongs to a wood products company Sumitomo Forestry Co, who also maintains a significant part of Japan’s forests. The construction will commemorate Sumitomo’s 350th anniversary.

The W350 tower will be mostly wood and 10% steel. Image credits: Sumitomo.

Sumitomo says the new structure, which they call the W350 Project, will be an example of “urban development that is kind for humans,” adding natural wood, greenery, and biodiversity to an otherwise grey and overly urban area.

The new building will be built almost exclusively from wood, using just 10% steel. The internal framework (columns, beans, etc) will be made from a wood-steel hybrid material, designed to withstand Japan’s extremely high rate of seismic activity. The Tokyo-based architecture firm Nikken Sekkei will contribute to the design.

Sumitomo’s plan also takes advantage of the fact that Japan’s forest cover is one of the most impressive in the world, and that the country’s wood stockpile is increasing each year. In a press release, they say that the project will not only be aesthetically pleasing and environmentally friendly, but it could also inject new life into an already mature economy. W350, they say, will popularize timber architecture, jumpstarting a revitalization of the forestry industry and sparking new interest in reforestation.

“The project offers the advantages of the re-use of timber, urban development that is kind for humans, and the vitalization of forestry. Wooden construction will increase through the optimal use of the strengths of trees.”

“We will make every effort to further enhance fire and seismic resistance as well as durability, thoroughly reduce construction costs, develop new materials and construction methods, and develop trees that will be used as resources.”

“We will strive to create environmentally-friendly and timber utilizing cities to Change Cities into Forests.”

Image credits: Sumitomo.

The 70 stories will provide 455,000 square meters in floor space, which will house shops, offices, a hotel and residential units. The facades will be covered in relaxing gardens and terraces. W350 will use more than 6.5 million cubic feet of wood

However, this innovative plan comes at a cost — Sumitomo will pocket an estimated ¥600bn (£4.02bn), almost double that of a conventional high-rise building. However, since construction won’t actually start by 2041, the company says that technological advancements will significantly lower this cost.