House in Koyoen | Tomohiro Hata architect & associates

The Koyoen region of Japan has a complex landscape of retaining walls, as well as winding stairs and streets. Within the area, Tomohiro Hata and the team have built a private residence with a form that blends with the flow and order of the city. The structure of the building integrates arcs, aches, and vaults to follow the shape of the twist and turn from the surrounding streets.

courtesy of tomohiro hata architect & associates

In the construction of the main structure of the building, the main road which is narrow and winding leading to the location has become the main challenge. While observing the main road leading to the site, the team of architects realized that it was not possible to transport building materials. Therefore, the design team began to consider options for using constructions that could be assembled and carried by hand. The focus is also shifted to arches as the shapes can pass through the span by combining small pieces. Structural materials are also maximized by the use of LVL (laminated veneer lumber), a material that can be disassembled and assembled into small, lightweight pieces.

In order to form an easy construction, the design team decided to form an arch with the LVL section being laser cut. The pieces are then stacked and connected by shifting the positions of the connectors so that they do not overlap. According to Tomohiro Hata's team, this is a primitive system in which only compression and tension forces flow along the grain of the wood cut out along the fiber direction. The wooden arches made in this way were held back and combined into the shape of a cross column, which was developed into a stretched and repeating structure.

Regarding the roof structure, it was decided to use a domed roof structure with a slope of 45 degrees. These roofs are slanted diagonally from a lattice of cross arches. This arrangement makes the cross columns and diagonal domes overlap each other, forming a multiaxial flow that responds to the spiral path around it. in this way, the structure extends to the expanse of the city, creating a house that blends into the landscape of the stretched slopes.