A ring-shaped wooden roof with a circumference of two kilometres will be erected using traditional techniques at the 2025 Osaka Kansai Expo. Sources: The Asahi Shimbun, photos: Japan Association for the 2025 World Exposition
The canopy, which will protect visitors to pavilions from sunlight and rain, will have a diameter of 675 meters and span an area of 60,000 square meters, the Japan Association for the 2025 World Exposition said.
The grand roof will be supported by the traditional “nuki” technique of joining horizontal beams and vertical pillars, which was used for the famed wooden stage at Kiyomizudera temple in Kyoto. An estimated 20,000 cubic meters of timber will be utilized.
“Wooden architecture is drawing attention around the world (from the perspective of UN sustainable development goals),” said architect Sou Fujimoto, who serves as the expo site design producer.
“Japan, which boasts a rich tradition of wooden structures as represented by Todaiji and Horyuji temples (in Nara), will be hosting an expo,” he said. “Given that our country is a global leader, I want to introduce the Japanese tradition to a world audience.”
The sloping roof will be 30 meters across. The outer circle of the ring will be 20 meters high, and the inner circle will be 12 meters high.
A skylight made of translucent material will be provided. The canopy is expected to be dismantled after the expo ends.
The expo venue’s construction cost of 185 billion yen will be shared in one-third portions by the central government, the business community and Osaka prefectural and city authorities. Of the total figure, 35 billion yen will be set aside for the roof.
While the Osaka city assembly expressed concerns about the rising costs of construction materials, organizers said they will try to keep the cost of the roof “within the budget.”
