A Wooden Supertall Proposed for Japan

Those eager to see such heights built in mass timber will have to wait a while: a statement from Sumitomo Forestry indicates a completion date of 2041, to "mark the 350th year since foundation of the business in 1691."

To date, the tallest tower built from mass timber is the Brock Commons Tallwood House in Vancouver, designed by Acton Ostry Architects. At only 17 stories, the hybrid wood-steel structure is relatively short, an indicator that building tall in wood is in its early stages and much research and construction needs to happen before timber tackles supertalls.

W350 would also, if ever built, be a hybrid wood and steel structure, with 90% of it in wood. To build at such heights in earthquake-prone Japan, the 70-story tower is designed with 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 most famous example of a braced tube structure, in steel at least, is SOM's John Hancock Center (now 875 North Michigan Avenue).

Beyond the benefits of wood construction on occupant comfort and well-being in its spaces for work and living, Sumitomo Forestry contends that W350 would sequester 100,000 tons of carbon dioxide. Furthermore, with 185,000 cubic meters of wood needed for W350 (equivalent to 8,000 houses), Sumitomo Forestry argues that it and other such projects would lead to the revitalization of forestry and result cities built from timber rather than concrete and steel.

In addition to bringing attention to mass timber construction through some nice renderings, the aims of the W350 concept are twofold: as an argument for the sustainable harvesting of Japan's cedar and cypress trees planted after WWII; and to increase the research and technological advancement of wood construction. Sumitomo Forestry admits that building W350 now would cost twice as much as steel or concrete construction, making it untenable. But if advances bring down costs dramatically between now and 2041, a timber supertall just might become a reality.