Nendo takes minimalism to its maximum with the Culvert Guesthouse in Japan

This archival piece of architecture lets minimalism reign supreme, exploring in its stark white, modern being, precast concrete tunnels that are placed and oriented in fantastic simplicity. The Culvert Guesthouse by Japanese designer firm Nendo, led by Oki Sato, designed this storage facility with an attached guesthouse, recording and displaying their furniture, products, and artwork, as a solo museum of all things Nendo.

Rendered in unapologetic straight lines and a single, pure shade of white, the Culvert Guesthouse is almost Mondrian in its essence. But how does it fare for the verdant site it calls home, which presumably, lost a ton of trees and vegetation to the construction of the new-age building?

Located within a quiet and nature-rich environment in Miyota-machi, Nagano Prefecture in central Japan, where streams meander through a thick forest of red pine, the ingenious Japanese architecture is made by stacking four tunnel-like concrete “culverts” bookended by glass walls, enclosed by a flat bleached roof at their centre, and a fifth volume residing solitary a few metres away.

Buttressed by simplicity, the Culvert Guesthouse eschews anything superfluous, including views, colour and décor of any kind except scantly placed dwarf trees, a few pieces of furniture and geometries born of the volumes' placement. People are welcomed into a heavily monochromatic, monastic space animated by a modest interplay of light and shadow on its plain surfaces as well as vistas framed at the end of each tunnel towards the resplendent forest outside.

The interstitial areas of the archive and residential space are generated by the placement of the four long concrete corridors oriented in opposite directions, bare except for a few sparsely placed products, furniture and greens. No grooves or pockets for services or visible windows can be seen, giving the interior design an almost untouched, strange, and eerie vibe, perfect as a backdrop for a neo-science fiction film.

Archive 1, an elongated, narrow storage room with a depth of approximately 40 metres runs on the ground floor, with a smaller tunnel placed parallelly across, hosting a kitchen, two toilets and a bathroom plus other water facilities. These two culverts are connected with a massive living and dining area in the middle, while the separated fifth volume, Archive 2, sits at a right angle to the first one. “…it is envisioned that more (storage) will be added to the site in the future as the collection grows,” relays Nendo, who are globally more known for their uncomplicated, functional and minimal product designs.

The level above sits poised on these two white-walled corridors, with a study room and Archive 3 concentrated in one, while the other one placed across houses a denuded, compact bedroom with a simple upholstered bed in white fabric and no seeable utilities or elements.

Piled and placed on an oval traced on the ground in exposed concrete, the ultra-minimal Culvert Guesthouse was built by means of a combination of precast and prestressed construction methods, where common parts are moulded and prepared in a factory off-site 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,” the Japanese architects explain.

The technical method of prestressing is employed in civil engineering structures such as bridges, where parts are aligned and then tightened with wires to join them, resulting in a seamless and smooth surface finish, obtaining a tight seal, and extended durability for the concrete architecture.

The common square-shaped parts weigh approximately 12 tons each, and 63 of these parts were used for the Culvert Guesthouse. “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 architects and designers relay. Fourteen wires were used to connect each tunnel and Nendo took immense care to apply uniform tension to each wire constantly. “The work involved gradually tightening the wires over time until a tension of 46 tons was finally applied to each,” they continue.

The stark nakedness of the entire contemporary architecture is given some dimension and decoration in the form of 45-degree reinforcement at every entry corner, also found in general box culverts, serving as a brace and aiding in earthquake resistance. These parts were connected to form the slender, tunnel-shaped volumes with an internal dimension of roughly 2 x 2.3 m.

The windows are made sans 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 (a translucent folding screen that typically acts as a room divider to provide privacy and diffuse light throughout the room in typical Japanese residential and hotel architecture).

The guesthouse and residence are also arranged with gravel and plantings, also seen in the exterior semi-open courtyard, visibly and intangibly uniting the outside to the interior. The used gravel was partially hardened with resin to make it easier to walk on.

"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,” the designers explain. The interiors, like the gallery’s skin, is minimal to its core, as a sparse, bare-bones space that embodies the firm’s no-nonsense design sensibilities and tenets.

Nendo also relays that the door handles would have looked "abrupt if installed as-is", sticking out as sore thumbs to the unornamented space. So they installed an original handle niftily designed to be concealed in the small gap between the door and the wall. 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 within the minimal architecture.

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

Project Details

Name: Culvert Guesthouse
Location: Miyota-machi, Nagano Prefecture, Japan
Year of completion: 2022
Client: Nendo
Architect and Interior Design: Nendo
Collaborators: Noritaka Ishibayashi, Ryota Maruyama, Daisuke Maeda, NIITSU-GUMI, P. S. Mitsubishi Construction