Curvilinear 'Shell House' Is Made With Plastered Earth

For most people, the words "earth architecture" conjure up images of small, traditional dwellings made with a variety of earthen materials and techniques, such as cob, adobe, or rammed earth. Indeed, building with earth goes back thousands of years, and can be one option worth considering if one is looking for a locally sourced and ecologically friendly way to build. What's more is that earthen architectural forms and the building process have now also evolved; we are now seeing more modern homes built out of rammed earth, earthen prototypes being 3D printed, or even this energy-efficient plastered earth renovation of a heritage home.

Whatever it may be, the tradition and evolution of building with earth continues on. In Japan, architect Tono Mirai is adding to that continuity with the realization of the Shell House, a small 409-square-foot (38-square-meter) retreat located somewhere in the forests of Karuizawa, a resort town found in Japan's Nagano prefecture.

The Shell House is designed for a couple from Tokyo—more specifically, a Shinto priest and a kindergarten director who were looking for a unique and environmentally friendly residence, where they could escape to during the summer. In response to the clients' wish for something that would harmonize well with its natural surroundings, the Shell House used a combination of traditional materials and building techniques, along with a modern flair and sustainable building strategies, in order to create a structure that is both one-of-a-kind, yet inconspicuous.

The rounded exterior of the house features a shingled skin that protects the plastered earth walls inside from fluctuations in temperature and humidity. One gains entry through a wooden door that is set on one side.

On the other side, we have an angular wooden deck that functions as a continuation of the ground floor from the inside. The deep eaves integrated overhead here recall traditional elements of Japanese architecture, where they serve to protect the building from rain and sun.

The interior consists of flexible spaces that include a raised platform where the clients can sit at the curved table to eat, or sleep with the use of traditional Japanese futons that can be rolled up and stored underneath the raised floor. At the rear of the platform, a long row of wooden slats hides doors that lead to the bathroom and storage area.

The distinctive asymmetric dome is made with seven wooden beams connecting to the main pillar, using a traditional Japanese carpentry technique that utilizes no nails. To accomplish this, the design team brought on the expertise of a master Japanese craftsman. This part of the project was essential to forming the rounded shape of the project's exterior, and the flowing lines of the interior were inspired by nature, as Mirai eloquently explains via Dwell:

"I felt that a straight and modern form would not be matched to the surrounding forest. Instead, it is an architecture that is inspired by the way humans are born from and return to the earth. The seven beams that emerge from the organic earth wall and form the roof are an expression of the cycle of life of humans and the universe."

The curvilinear fireplace echoes the organic forms of the walls and ceiling, serving as the central anchor of the hearth in a compact home.

Across from the fireplace, there is a curved kitchen island that helps to extend the functionality of the kitchen. With the glass patio doors completely open, it feels like the interior becomes an extension of the outside.

A set of stairs winds up behind the platform, alongside a curved wall made of plastered earth and wood. A variety of local, FSC-certified wood species was used, including Japanese red pine, cypress, and cedar, with much of the materials used sourced within 93 miles. Additionally, the house was built with energy efficiency, and passive heating and cooling in mind, on top of other more subtle considerations, says Mirai:

"I feel this project expresses the power of nature and humanity. I was inspired by the spirits, the place, the wood and earth materials of the forest, and the craftsmanship of the Japanese artisan. I respect all of them."

The mezzanine above serves as another flexible space to use, either for overnight guests or as a quiet space to relax.

Even the rounded lines of the bathroom, down to the organic shape of the rock covering the drain, echo the natural flows of the nearby brook.

The notion that the "spirit of the place" should inspire the building process is the driving force behind the Shell House, in addition to the remarkable universality of earth, says Mirai:

"Earth is the building material, but this is also the material that all building materials return to. Earth is the material that connects everybody on the globe."

To see more, visit Tono Mirai Architects.