A storage facility for archiving furniture, products, and artwork in Miyota-machi, Nagano Prefecture, with a guesthouse attached. Located in a quiet and nature-rich environment where streams weave through a thick forest of red pine, the tunnel-like architecture took shape through a combination of precast and prestressed construction methods.

▼项目概览,Preview © Takumi Ota

▼鸟瞰,Aerial view © Takumi Ota


The prestressing method is a technique used in civil engineering structures such as bridges, in which the parts are aligned and then tightened with wires to connect them. This results in a seamless and smooth surface finish, obtaining a tight seal, and durability.

▼隧道般的结构融合了预制建造和预应力的施工方法,The tunnel-like architecture took shape through a combination of precast and prestressed construction methods © Takumi Ota

▼建筑外观,Exterior view © Daici Ano


▼设计示意,Sketch © nendo

For precast construction, common parts are molded in a factory and assembled on site. An example of its applications in infrastructure projects is the box culvert (box-shaped concrete structures), used to store waterways, pathways, power lines, and communication lines buried underground. However, since the method itself does not provide a leak-free composition nor does it allow for stacking, both necessary for this architecture, prestressing was also used to connect the parts together.

▼堆叠的体量,The stacked volumes © Daici Ano

▼建筑与自然环境,The building and its natural surroundings © Takumi Ota

© Daici Ano

常见的方形构件每个约重12吨,该项目共计使用了63个这样的构件,它们的尺寸是根据运输卡车的荷载大小和起重机可以吊起的重量计算得出的。建筑的入口角采用了一般箱涵也会使用的45度钢筋,起到支撑和加强抗震的作用。相互连接的构件创造出内部尺寸约为2 x 2.3米的细长隧道形空间,这几个“隧道”通过14条钢索连接起来,并在所有时刻下对每根钢索施加均匀的张力。随着时间的推移,钢丝逐渐收紧,直至每根钢丝被施加的张力达到46吨。

▼视频 – 施工过程,Video – making

The common square-shaped parts weigh approximately 12 tons each, and a total of 63 of these parts were used. The size of the parts was derived from the loading size of the delivery truck and the weight that could be lifted by a crane. The 45-degree reinforcement at the entry corner, which is also found in general box culverts, serves as a brace and enhances earthquake resistance. By connecting these parts, a slender, tunnel-shaped space with an internal dimension of approximately 2 x 2.3 m was created. Fourteen wires were used to connect each “tunnel” and care was taken to apply uniform tension to each wire at all times. The work involved gradually tightening the wires over time until a tension of 46 tons was finally applied to each.

▼堆叠的“隧道”,The stacked “tunnels” © Daici Ano

▼“隧道”近景,Detailed view of the “tunnels” © Takumi Ota


The building is composed of four stacked “tunnels” covered with a roof in the center. In addition to a long, narrow storage room with a depth of approximately 40 meters, there are two smaller storage rooms, but it is envisioned that more will be added to the site in the future as the collection grows. The kitchen, bathroom, toilet, and other water facilities are concentrated on the first floor, and a compact bedroom and a study are located on the second floor.

▼首层空间,Ground floor space © Takumi Ota

▼户外庭院,Outdoor courtyard © Daici Ano

▼入口细节,Entrance door © Takumi Ota


The windows were made without metal frames as much as possible, and high-transparency glass measuring up to 10 meters in length was fixed into the grooves in the same manner as shoji screens. The gravel and plantings used in the exterior were also arranged in the interior to draw the outside environment into the interior. To make it easier to walk on, the gravel was partially hardened with resin. Instead of just pouring resin over the gravel, which is usually the case, the resin was applied to the base first and then gravel was laid on it so that the surface wouldn’t become glossy.

▼玻璃长窗,The long window © Takumi Ota

▼中央带顶空间,The covered central space © Daici Ano

▼餐厅/起居室,Dining / living room © Takumi Ota

▼餐厅储物墙,The storage wall © Daici Ano

▼起居室和庭院,Living room and courtyard © Daici Ano

▼楼梯,Staircase © Daici Ano

▼二层走廊,Second floor corridor © Takumi Ota

▼从二层俯瞰一层,View from the second floor © Daici Ano

© Takumi Ota

▼室内细节,Interior view © Daici Ano


In addition, the door handles would have looked abrupt if installed as-is, so an original handle was designed, which hides in the small gap between the door and the wall.

▼隐藏的门把手,The hidden handle © Daici Ano

▼储藏室,Archive © Daici Ano

© Takumi Ota

© Daici Ano

© Takumi Ota

▼旅馆卧室,Bedroom © Takumi Ota

▼书房,Study room © Takumi Ota

▼窗景,View © Daici Ano


The bathtub is carved into the floor, such that the water surface aligns with the floor, creating the appearance that the tunnel shape is continuous.

▼浴室,Bathroom © Daici Ano

▼浴缸细节,Bathtub © Takumi Ota


The resulting space is less architectural, but rather a project that combines civil engineering concepts with product design details.

▼入口细节,The entry door © Takumi Ota

▼室内细节,Interior details © Daici Ano © Takumi Ota

▼夜景,Night view© Takumi Ota

© Daici Ano

© Takumi Ota

▼场地平面图,Site plan ©nendo

▼一层平面图,1F Plan ©nendo

▼二层平面图,2F Plan ©nendo

▼剖面图,Section ©nendo

Collaborator: Noritaka Ishibayashi, Ryota Maruyama, Daisuke Maeda
Photographer: Daici Ano, Takumi Ota
filming and editing : Toru Shiomi
filming: Takahisa Araki