It was upon the exhibition of her own house — designed together with fellow architect Fuminori Nousaku — that first brought Mio Tsuneyama’s practice to a broader audience. Pushing boundaries of what constitutes an architectural work while committing to making use of existing structures, in this interview Tsuneyama explains her claim to agency through a deeply grounded engagement with the discipline.

This conversation is part of KoozArch's issue "Terra Infirma."

FEDERICA ZAMBELETTI / KOOZ Let’s start by addressing your relationship to soil, both as an architect and a citizen. When did you start thinking about soil; how did this shape your approach to architecture and how you live the city?

MIO TSUNEYAMAMy deep interest in soil began in 2018 through two key encounters. The first was a soil improvement project by Takada Zoen, which utilises mycelium networks to rehabilitate wastelands across Japan. This project revealed how soil can be transformed into a thriving environment for plants and microorganisms through simple practices like digging holes to introduce water and oxygen.

The second encounter was with the book The Hidden Half of Nature: The Microbial Roots of Life and Health by David R. Montgomery and Anne Biklé. The book explores how fungi and microorganisms interact both in the soil and within the human body. Understanding that these microscopic organisms coexist with plant roots and exchange nutrients and information heightened my awareness of soil, turning what was once an abstract concept into something tangible and vital.

KOOZ In particular I would like to take your Holes in the House project — that is, the renovation of your home in Tokyo — as a case study to discuss your relationship to soil, starting from the very fact that the project is itself a renovation and thus avoids the act of excavation. How do you weigh the choice of working within an existing structure or having to build anew?

MTI view architecture through the lens of material cycles, rather than opposing terms of new construction or renovation. Utilising existing buildings is crucial for reducing waste and conserving earth’s resources. However, it often demands more effort to update structures to meet modern standards for earthquake resistance and environmental performance.

Conversely, new construction offers opportunities to use recycled and biodegradable materials, or materials that are less harmful to soil. It also enables the incorporation of soil-friendly construction methods, such as independent foundations and rainwater infiltration techniques. New construction can embrace innovative ideas and techniques that promote environmental sustainability and resource efficiency.

KOOZ When weighing up such choices, certain elements seem to be out of our hands — especially coming up against national norms and structural standards, such as the frequent revision of earthquake standards in Japan. How do you approach factors that can often seem like normative hindrances?

MT Japanese building codes, created for an era of mass production and consumption, need to be updated to address the growing focus on renovation and material reuse. Instead of strictly adhering to outdated standards, architects should challenge and redefine them. The codes often include unreasonable or obsolete standards due to frequent revisions, and while changing social systems is complex, architects can influence perceptions and foster innovation through their projects.

For instance, in projects like Piles and Pointed Roof and House on Classical Elements, we implemented independent foundations despite the Japanese building code's requirement for continuous foundations. After extensive collaboration with structural engineers and rigorous questioning by government officials, we achieved approval for this method. Similarly, in the String Brace House, we utilised high-strength aramid fibre bracing and explored horizontal reinforcement methods for self-construction, confirming safety through structural calculations. These experiments illustrate where contemporary architectural design can thrive, emphasising practical innovation over mere eccentricity.

KOOZ When thinking about the structural stance of a project the first thing is the connection to the ground and thus our foundations. How do you approach this point of contact? What strategies can be implemented so as to reduce the weight and footprint of the building on the soil?

MT I'm exploring how traditional Japanese building methods can inform modern architecture, particularly regarding foundations. Traditional Japanese architecture often employs independent stone foundations, where crushed stones are placed beneath each foundation stone and carbonised pine piles are driven into the ground. The carbonised, porous surface of these piles supports microorganisms, forming a mycelium network that strengthens the soil structure.

This traditional approach teaches us the value of designing foundations that do not obstruct the flow of water and air. It suggests that we can develop new independent foundation systems by integrating these principles with modern materials and techniques.

KOOZ Holes in the House is representative of your interest in off grid living and thus tapping into local resources, how did this interest shape the adaptive reuse project and approach to the soil?

MT At Holes in the House, we harnessed the power of soil by breaking up the concrete in a small parking space and returning it to soil. We began by dumping food scraps and wood shavings there and discovered that some materials are easily reintroduced into the soil, while others are not. For instance, plywood — a water-resistant material often used in modern wooden houses — remains in the soil indefinitely due to its glued composition. Unlike natural wood, it doesn't absorb or release moisture, leading to humidity issues and mould growth, particularly during Japan's humid summers and rainy seasons. As I became more attuned to soil dynamics, I realised that materials that don't return to the soil also lack positive effects on human health and aesthetics. Consequently, I started opting for biodegradable materials like wood fibre, cotton, solid wood, and paper.

In urban environments, allowing rainwater to percolate into the soil can significantly enhance the subsoil ecosystem. In Tokyo, rainwater is usually directed through gutters to communal drainage systems, where it is then discharged into the ocean or rivers. This practice, combined with asphalt and building cover, depletes soil structure and increases the risk of landslides and other hazards. By creating small soil patches, we can facilitate oxygenation through rainwater infiltration and establish a network of water and mycelium, fostering a soil structure that supports plant growth. Plants in these patches contribute to cooling through transpiration and shading, promoting wind flow and alleviating the heat island effect.

The soil introduced a food cycle into this small house. Seeds from food scraps returned to the soil yielded tomatoes the following year. When these tomatoes were dried on the rooftop, they became sweeter and more flavorful, highlighting the benefits of natural sunlight. Solar cooking, whether performed on the rooftop or a windowsill, moved cooking beyond the conventional system kitchen, leading to a rethinking and deconstruction of the traditional kitchen concept.

KOOZ The project embraces the fact that if construction waste accounts for 20% of waste worldwide we must create architectures which are already preconfigured to become waste and thus favouring a “bio cycle” approach. How do you source the materials used throughout your projects and how do you navigate their implementation over the use of cheaper plastics and so on?

MT We aim to make use of waste and scrap materials that are often generated in densely populated cities with significant construction activity. While biodegradable materials are preferable for biological cycles and a healthier indoor environment, we also actively repurpose materials destined for disposal, even if they are petroleum-based. For example, the insulation on the south wall of our fourth floor is made from blue Styrofoam, salvaged from a friend’s construction site. Similarly, the cypress and cedar rimmed boards used for the flooring and wall finishes on the ground floor were salvaged from a public art museum we were involved with. These boards, which were part of the exhibits, were destined to be discarded after the exhibition period, but we rescued them from a garbage dump, giving them a second life in our space. Additionally, the wood fibres used for insulation on the upper floors were obtained from a manufacturer's dead stock, with only transportation costs. By regularly sourcing scrap materials, we begin to uncover the hidden world of distribution and disposal. This process opens up access to unexpected resources that would otherwise go to waste.

KOOZ The use of sustainable materials also significantly impacts the budget of a project – how do you evaluate these solutions to ensure projects that are also economically sustainable?

MT The House on Classical Elements, completed last year, utilised cedar lumber sourced from a mountain within 200km of the construction site. In Japan, lumber distribution typically involves multiple intermediaries, each taking a margin from the forest to the construction site. However, the carpenters at House on Classical Element used a traditional method with foundation stones and partnered directly with the forestry cooperative. By installing a mobile sawmill at the forest management office, the cooperative handled the natural drying and sawing process, bypassing intermediaries.

This direct approach allowed them to purchase naturally dried lumber, which is stronger and more durable than machine-dried wood, at a lower cost. While natural drying requires more space and labour, the system has proven to be a more sustainable and economical way of using high-quality materials. Revisiting the conventional distribution system offers a shortcut to sourcing better building materials.

KOOZ Beyond the environmental benefits, the use of such materials requires ad hoc solutions and training which differs from the use of concrete, metal and plastics more commonly used in construction. What is the potential of this in relation to the construction labour force?

MT The construction of traditional Japanese minka houses embodied a communal aspect. For example, the process of re-thatching roofs, known as yui, was a collective effort carried out by the community every few decades. This practice was passed down through generations, with a house in the community being re-thatched each year. Residents were actively involved in both building and maintaining their homes, enabling regular upkeep and repairs. As a result, wooden houses were preserved and used for many generations, with parts and materials being replaced as needed.

The materials, techniques, and labour for building houses were sourced locally, and construction was seen as a way of life rather than a form of labour. In contrast, the current built environment operates within a capitalist framework. However, small-scale projects offer opportunities for experimentation with minimal risk. These projects can explore new construction materials, traditional techniques, innovative structural forms, and user-driven building methods. Ideas developed in these experimental fields can evolve through iteration and eventually become standardised, paving the way for larger-scale applications.

KOOZ Going back to the soil, you conducted research on urban farms in cities such as New York, Paris, Berlin, Lausanne Daegu and Tokyo developing hypothetical projects that aimed to uncover the potentialities of urban soils in relation to urban lifestyles. What observations did such research yield and how could they point towards a different kind of urbanism?

MT The self-sufficiency of food within the existing urban framework has led to the emergence of a new architectural typology. As cities become more densely built, this typology becomes increasingly unique, blending creativity in securing natural resources like soil, sunlight, wind, and water with local lifestyles and cultures. In Manhattan, for instance, citizens have initiated pocket gardens on individual plots, supported by the Parks Department. In Brooklyn, vocational agriculture has taken root on the rooftops of large warehouses. In Tokyo, planter gardens are thriving in alleys and on balconies, often used for drying clothes. Meanwhile, in Paris, community gardens in apartment parking lots are fostering new, cross-generational, and cross-cultural communities, especially in the Périphérique.

The key challenge in realising urban agriculture lies in designing not only the physical resources but also the social systems that manage them. There is vast potential for commons-based management to offer an alternative to the current polarised public and private sectors, particularly in today's capitalist society.

Bios

Mio Tsuneyama is a Japanese architect and founder of Studio mnm. She began her study of architecture at Tokyo University of Science, Japan and completed at École Polytechnique Fédéral de Lausanne (EPFL) in 2008 as Swiss Government International Scholarships student, where she taught as a visiting professor in 2022-2023. She worked as an architect at HHF Architects in Basel after her study until she went back to Tokyo to start her own practice Studio mnm in 2012. She teaches at several private universities in Japan and began teaching in the role of guest professor at EPFL in 2022.

Federica Zambeletti is the founder and managing director of KoozArch. She is an architect, researcher and storyteller whose interests lie at the intersection between art, architecture and regenerative practices. In 2022 Federica founded KoozArch with the ambition of creating a space where to research, explore and discuss architecture beyond the limits of its built form. Prior to dedicating her full attention to KoozArch, Federica collaborated with the architecture studio and non-profit agency for change UNA/UNLESS working on numerous cultural projects and the research of "Antarctic Resolution". Federica is an Architectural Association School of Architecture in London alumni.