The site was bottom of the Kusatsu river which runs into the largest freshwater lake in Japan, Lake Biwa. Bottom of the river is higher than the surroundings because the embankment zone of the river has been raised repeatedly due to the heavy rains. Kusatsu River became a park after it was replaced by a new river.
We made three roof with variations in size float as a metaphor to remind the image of the old houses that were passed down to this neighborhood. Those enhance people to imagine that they are very familiar, comfortable and lovely place for the neighbors. It will act as a lighthouse which fascinates and draws the people. Even though the varieties of the commercial shops will appear bellow floating roofs, the large roofs will embrace the diversity of them. We have created group of floating roofs on the bottom of the past river, it will create a meaningful good spaces for human. They have experiences with their families and friends under the big roof. They remember the warmth of fireplaces, the light beams of the sunlight through the smoky atmosphere from top-light, smells, the soil floor’s coolness and so on. Those stimulate the perception of people. We tried to evoke that kind of experience with present materials and skills.
This project has three commercial facilities named Cocoriva in Kusatsu River Park. Each building has a distinguish structure system with notional abstract and steep roof which became a landmark in Kusatsu city. It will be a gathering space for the neighbors because the people feel comfortable with the atmosphere that is created below the large roofs. The metaphor of the intimate roof reminds people of the perception and experience which they accepted below the roof, “Yoshi-buki." The three structure has variations in size and each building has metaphor of local and old-time roof structure “Yoshi-buki”, something which covers the human space. Very like the thatching method, Yoshi-buki roof is crafted with dry straw vegetation that are available along Lake Biwa since the ancient times.
The steel truss system was chosen to lighten the structure parts as much as possible to make it easy to be assembled with local hands. The building structures are well ventilated during the summer with the chimney efficiency. The roof structure has thin steel plate floating above the top light to secure the ventilation path. Our intention was not to imitate the physical shape of the traditional roof, but to make present houses with modern local technique.
The ground data shows that the site is expected to have land liquidation during the large earthquakes. The structure is light enough to be jacked up if the building dose experience subsidence. The building structures are floating on top of the soft grounds like the floating boats instead of creating deep foundation. The roof top will act as a lighthouse to guide people during the night. The perception and experience will attract people.