Hokkaido CLT Pavilion: a building entirely made of timber

The project aimed to understand the characteristics of CLT and use CLT for all structural components including floors, walls, and roofs. The approach to the building is on the national highway side, considering the flow of visitors. A corner opening to the southeast with a view of the greenery, eaves overhanging 2,450mm, and a terrace are provided.
A corner opening was placed on the northwest side taking into account the flow of cars from the national highway, to highlight the CLT structure. Taking advantage of the beam-free nature of the building, a crevasse-shaped high sidelights were installed in the center of the building, and laboratories made of Todo fur and larch were placed on each side of the crevasse. The size of the CLT panels was determined based on the maximum possible size that can be loaded on a trailer to reduce the transportation cost. We controlled the cutting allocation of the motherboard at the design stage, and achieved a yield rate of 93%.
Taking full advantage of the dry construction method of CLT panels, the foundation was constructed with piles and steel members using a dry construction method.
Ten piles with a diameter of 216.3 were driven The site is located within the Forest Product Research Institute in Nishikagura, Asahikawa-shi. This is a laboratory building dedicated to the observation and studies of CLT architecture from various perspectives including its strength, environmental changes, and material properties for seven years as part of Hokkaido's forestry research.
The project aimed to understand the characteristics of CLT and use CLT for all structural components including floors, walls, and roofs. The approach to the building is on the national highway side, considering the flow of visitors. A corner opening to the southeast with a view of the greenery, eaves overhanging 2,450mm, and a terrace are provided.
A corner opening was placed on the northwest side taking into account the flow of cars from the national highway, to highlight the CLT structure. Taking advantage of the beam-free nature of the building, a crevasse-shaped high sidelights were installed in the center of the building, and laboratories made of Todo fur and larch were placed on each side of the crevasse. The size of the CLT panels was determined based on the maximum possible size that can be loaded on a trailer to reduce the transportation cost. We controlled the cutting allocation of the motherboard at the design stage, and achieved a yield rate of 93%.
Taking full advantage of the dry construction method of CLT panels, the foundation was constructed with piles and steel members using a dry construction method.
Ten piles with a diameter of 216.3 were driven into the ground, parts of the piles were extended to the ground surface, and 200mm H-section steel bars were assembled in a double cross pattern on top of them.
The joints between the piles and the steel members had to be made with very high construction accuracy, and all the errors in the pile positions were controlled to less than±10mm.
CLT panels were joined using pull bolts in the wall and through bolts, which are bolted through a single steel member inserted from the bottom to top. Details were designed in such a way that no hardware is visible on the interior and exterior walls.
The construction was completed in just ten days from start to completion of the raising of the building, which is significantly shorter compared to reinforced concrete construction. Wood is used as a material to create a space with a sense of warmth.
Two types of CLT, Todo fur and larch from Hokkaido, were used for the strength test, and each type is used on either side of the crevasse. The size of the CLT panels was determined based on the maximum possible size that can be loaded on a trailer to reduce the transportation cost. When ordering materials, we controlled the cutting allocation of the motherboard at the design stage, and achieved a yield rate of 93% and avoid wasteful cutting.
The stairs of the approach were made by cutting a single piece of CLT panel (5 layers, 7 plies, t=210) into a stair shape.
The roof overhangs by 2450mm in the strong axis direction and by 1700mm in the weak axis direction.
By stitching CLT inverted beams to the roof in the orthogonal direction, the roof can protrude significantly in the weak axis direction, which is not usually the case.

Since the area is subject to heavy snowfall with a depth of 1.3m, the deflection due to snow accumulation will be measured to verify structural characteristics of CLT in the future.
CLT roof panel layout plan: CLT inverted beams were installed so that the roof can overhang significantly in two directions.
In order to shorten the construction period as much as possible using the CLT dry construction method, the foundation was constructed with the same dry construction method. Ten piles with a diameter of 216.3 were driven into the ground, parts of the piles were extended to the ground surface, and 200mm H-section steel bars were assembled in a double cross pattern on top of them. The joints between the piles and the steel members using high strength bolts had to be made with very high construction accuracy. These measures resulted in a significant shortening of the construction period, and we achieved a design with a sense of lightness by detaching the building from the ground.
The size of the motherboard and the cutting position were carefully studied to reduce cost by minimizing the amount of cut waste. By keeping the strength grade and thickness of CLT as consistent as possible, the yield rate was improved from 75% to 93%, thus achieving less wasteful panel collection. In addition, CLT scraps were used to cover and protect the sides of the CLT roof and floor with thin CLT sheets (t=30,) thus reducing waste while extending the life of the building.