Small Home: Bay Window Tower House

How did you find the experience of designing your family home together as your first collaboration?

Although it's our home, we designed it considering that we might not live here forever – it could be used by others or converted into a shop or office in the future. Therefore, we didn't approach it with any special emotional attachment just because it's our house; we treated it as one of our projects.

You live here with your two children and two cats. Can you please tell us their names and ages, and what they each enjoy most about living in this special and unusual home?

Our children are Rihito, 10 and Mako, 8. Our cats are Andrei, 13 and May, 13. The cats move around according to seasonal and daily changes in light and wind, finding comfortable spots. In summer, they prefer the lower floors where it's cooler, and in winter, they stay on the upper floors where it's warmer. The children seem to enjoy being able to do what they want in various places inside the house and use the space according to their moods: reading books on the upper floor or drawing on the lower floor, freely using the bay windows as benches and tables. Rihito particularly likes looking at the sky from the rooftop, while Mako enjoys playing the piano in the semi-basement space.

All the living in your home is done 'in the round' – in the centre of the house, across these multiple levels, like a child's fantasy tree house. When and how did this concept come into the design process?

From the beginning, we had "love our neighbours" as our design concept. Even in Tokyo's densely populated areas, we wanted to ensure that we wouldn't block the windows of neighbouring houses, allowing light and air to reach their interiors unobstructed. As we refined this approach, we arrived at an octagonal floor plan that approaches a circular shape.

What about the cork? I understand the inspiration came from a building you saw in Portugal. What was it about the material that made it so appealing?

We were searching for an exterior material that could serve both as external insulation and a design element while being environmentally friendly. Cork is harvested from the bark of cork oak trees without cutting down the trees. The bark regenerates every nine years and can be harvested again. The crushed bark is placed in moulds, heated and pressed, binding it together with its own natural resin – no chemical adhesives are used. As a result, for non-humans – for flora and fauna – this house behaves like a large cork tree. These aspects really appealed to us.

Longevity in built structures is not always the chief ambition in Japanese architecture, and yet this was a major consideration as part of your design – to design a building that would endure and age well long after you've moved on from it. Can you tell us more about this thinking and motivation on your part?

Since the house is located near a station, it's in an area that could serve various purposes in the future. Therefore, we avoided making it too overtly residential in design to maintain flexibility for other uses, and we selected materials that would become more attractive with age, ensuring that the Bay Window Tower House would develop a deeper connection with people over time.

I love the idea of the bay window being embraced as a site for all kinds of tasks and living… Can you tell us about how this idea fed into your design?

The Bay Window Tower House has a very compact floor plan of about 20m2 per floor. If we were to place furniture like sofas in this space, it would occupy most of the area and define the space too rigidly. This design allowed us to keep the spaces undifferentiated without assigning specific functions to them. As a result, our family gained the freedom to behave as we wish without constraints like "this is how one should behave in this space".

Talk to us about your research into bay windows and the possibilities they opened up in your design?

Spaces like bay windows that partially enclose the interior can be found worldwide. In Japan, the engawa (veranda) in traditional wooden houses is a similar concept. Spending time in bay windows, which are the most exterior-facing interior spaces, provides spatial expansion in the compact Bay Window Tower House. One of our most significant discoveries was how it allows us to live while being strongly aware of the seasons, which are very distinct in Japan.

There are three different types of bay windows in the design. Can you please tell us about the types and why the different types were included?

Environmental analysis revealed that different locations required different types of bay windows – some for capturing light, others for catching breezes, and some for preventing heat gain. Therefore, we designed different types of bay windows for these specific roles.

I love the way your home makes so much use of its internal perimeter. It's so counterintuitive to how we tend to think about organising and utilising the spaces within our homes. We more often use these perimeters for storage and display rather than the more active parts of living. It opens up so much space in the rest of the home. How have you found the experience?

The areas around the bay windows aren't limited to specific functions, so they can accommodate various activities and, with some creativity, can be used very effectively. It's very comfortable. For instance, we've had events where many people sat in the bay windows as audience seats, making it like a mini theater for performances.

The benches or ledges that span the lengths of the walls on the first and second floors are simple and yet so clever in the range of functions they can play – from occasional seating and dining seating to bookshelves or a place for a TV or artwork… They are so versatile. Was this adaptability always forefront in your mind?

Yes, this was planned from the beginning. When having a party, we store the TV and artwork under the bay window bench, which then becomes seating. Since the spaces don't have fixed functions, we can flexibly adapt them according to the situation at hand.

What have you learned from living in your design?

Living in the highest interior spaces closest to the exterior and utilising the three types of bay windows has heightened our sensitivity to subtle climate changes and nurtured our connection with nature. This has been our most significant discovery.

For each of you, what are your favourite details or spaces within the design?

I like the simple, detail-less aspect of the cork, and how we laid the 35mm-wide flooring boards following the offset of the external shape. I particularly appreciate the subtle details of the space and the visualised centre in the design.

For Yuko, it's the iron coating and plastered walls that contain mica, which gives off a subtle glow when light hits at certain times of day. The texture also changes with age. Yuko really loves these details that show the passage of time.