Boundary House – A Cost-Effective Steel Frame House by Niji Architects

This modern small house, called Boundary House, can be found in a residential street in Tokyo. The house was created by Niji Architects who had to develop a cost-effective design due to a limited budget, while also incorporating the clients other requirements.


Prefab Steel House - Niji Architects - Tokyo - Exterior - Humble Homes

Boundary House makes use of light gauge sections (LGS) – mostly lipped channels – that are lightweight, easy to transport, and easy to work with. The steel was prepared in a factory, where it was cut to length and drilled for bolt holes. Hardware for each of the connections were also fabricated in the factory.


Prefab Steel House - Niji Architects - Tokyo - Living Area - Humble Homes

The result of all the factory prep-work, is a house structure that could be assembled on site without the need for any welding – all the connections are bolted, reducing costs. Because the structure is so light, they managed to avoid having to install a piled foundation, again saving more money.


Prefab Steel House - Niji Architects - Tokyo - Staircase - Humble Homes

The walls and roof feature rigid insulation panels that were directly fastened to the structure. The outside of the house looks very industrial; you would be forgiven for thinking it was used as an office. The industrial theme continues to the interior were the steel has been left exposed.

Prefab Steel House - Niji Architects - Tokyo - Bedroom - Humble Homes

Windows have been placed high and low on the walls in an attempt to maintain privacy. Other windows like those in the patio doors and balcony above, provide viewpoints out over the surrounding cityscape. The first floor is home to a living and dining room, a tiny kitchenette, and a bathroom with a separate toilet and powder room.

Prefab Steel House - Niji Architects - Tokyo - Floor Plans - Humble Homes

The second floor contains space for up to three bedrooms and another toilet. Storage closets are used to divide up the space between the rooms. In its current state the home looks very bare and minimalist. Like it or hate it, it seems that the “unfinished” trend in Japanese architecture is showing no signs of disappearing any time soon.

For more Japanese houses check out this redesign by Tato Architects that introduces curved partitions to a traditional Japanese house. Or, Takeshi Shikauchis small houses that features two residences in one. See all Japanese houses.

Via DesignBoom
Photos: Niji Architects

Niall Burke

Structural engineer by day, tiny house designer by night. Niall has a keen interest in small spaces, green design, and sustainability. He started developing Humble Homes while studying for his masters degree in engineering. He is the founder and managing editor of Humble Homes.

  1. This is an excellent design! I love the quiet minimal look and it appeaars to be an excellent use of materials

  2. I definitely like this one more then the others I have seen. Still would like to have seen pictures of the bedrooms. I like that you have the privacy plus the windows maybe a little bit bigger but I definitely like this one a lot. It had the railing for the stairs. I would have like to see pictures of the kitchen also.

  3. Is this house insulated ? Presumably so. If not, then of course this place would be totally unliveable. Interesting prefab idea but, Good Lord, this place is stark.. These comments are politely submitted.