This is an interior renovation project of an existing two-story timber structure house in Tokyo which was built approximately 40 years ago.

The clients, a young couple and the wife’s parents, were already living here before the renovation.

Soon after, the wife’s grandmother, who lived alone in the countryside far from Tokyo, also decided to move in. As such, the clients requested to renovate the house and to make it suitable for accommodating 4 generations—the grandmother (1st generation), the parents (2nd generation), the clients (3rd generation), the clients’ son (4th generation).

As the age as well as daily living rhythm of each family member are different, creating a space to promote a comfortable connection among them was one of the major challenges of the project.

Another focus was the provision of a comfortable living environment. The existing conditions of daylight and ventilation were not preferable since the existing rooms were split into smaller functions and as such they were not open to the exterior environment nor to each other, which led to poor daylight and natural ventilation.

Firstly, the architects carefully studied the arrangement of rooms to take full advantage of existing windows thus maximizing natural daylight and ventilation.

Furthermore, common spaces adjacent to private rooms were secured in each floor. They act as communication hubs to seamlessly connect different generations. The private rooms are also exchangeable among the members so as to enhance communication between generations; similar to a share-house lifestyle.

However, since private rooms were prioritized in planning, securing enough natural daylight in the common space on the 1st floor became another challenge; particularly as it faces north. Consequently, a catenary ceiling was designed on the 2nd floor to better reflect daylight into the 1st floor; this became a distinguishing feature of the house.

At the same time, the existing structure was renewed.

Although the columns were densely arranged in accordance with the existing partitions, the architects found that the existing house was structurally unbalanced and lacked the necessary structural resistance. As such, they decided to add reinforcements through supporting beams and structural plywood whilst optimizing the use of its existing structural components. As a result, some columns were deemed redundant and thus removable (in total 20 columns were removed), providing an opportunity to create open spaces.

The catenary-shaped ceiling now gently envelopes all 4 generations of the family who ultimately enjoy living in a space abundant of natural daylight and ventilation.

Data Sheet

Official name of the project: house for 4 generations

Location: Tokyo, Japan

Budget: JPY 18M

Project dates/project end date: 2015 to 2017/April 2017 

Area: 140sqm

Client: Private client

Architects: tomomi kito & architect associates

Designers: tomomi kito & architect associates

Collaborators: 

• Structural designer: Building Structure Institute

• Technical advisor: Yutaka Misawa

• Lighting advisor: Kanae Hagiwara

Photo credits/Photographer(s): satoshi shigeta

About tomomi kito architect & associates

tomomi kito architect & associates was founded in 2014 by Tomomi Kito (born in Aichi, 1978). He has completed the Master Course of Architecture at University of Pennsylvania in 2004 after receiving the Master and Bachelor degrees in Japan. He worked at architectural design offices in Europe and at Architecton in Tokyo. The design approach is based on the respect for and integration of the nature of a site—climate, topographic, environmental conditions, etc., and on the activities of the building’s residents.