Many of urban housing lots in Japan these days have been divided into pieces to leave small, narrow spaces, where, in general, various functions are laid out around a stairway in the center of a single room. This may be a solution to fully utilize the limited space. My concern is whether it is comfortable to be in the house with the stairway and other details of the house always in sight. I dared divisions to limit the visibility to give a sense of expanse to the existing space.

I coordinated, in a solid space of 4.8 by 7.4 meters floor space and 8.2 meters in height, six levels of floor, a stairwell through three floors with a skylight covering the top, another stairwell through two floors with another skylight covering the 1.5 by 1.5 meters top, an enclosed sun deck, etc.

I used material serving both as structural member and fire resistant board for the basis of wall surface treatment to comply with strict fire prevention regulation, which allowed using finish of a broiled cedar of high durability and of a calm appearance.

When you step in the entrance hall, you will be facing an atelier of concrete floor the level of which is the same as the outside ground surface. The client will ride his motorbike in for maintenance or for storage and for enjoying DIY hobbies there. On the left provided is a bedroom of half underground, where the entire interior is finished with paulownia wood for humidity control. From a little leveled up floor you will be stepping up to the dining and kitchen on the second floor, or further turn around and step up by three to the living room, or further turn right to the stairwell, or further turn to step up to the third floor. You will be thus rising spirally.
The living room of open atmosphere with direct sunlight introduced through the three windows, the dining room of calm atmosphere with the skylight six meters above through which the sunlight is reflected down to fill the room with constant softness all the time, and a bathroom on the top floor filled with sunlight and yet privacy is secured – all these rooms of different nature are combined with coordination. The inside of the stairwells cannot be seen from each room but the sunlight is delivered to each room through the skylights and through the stairwells. This invisibility together with leaking light is giving a sense of ever expanding space in a small building.