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Up on the roof: House By Tezuka Architects (Hadano, Japan)

Topped by a roof deck that doubles as an external room, this family house is an inventive if vertiginous response to Tokyo’s lack of space

Originally published in AR October 2001, this piece was republished online in September 2011

This modest family villa in the suburbs of Tokyo is an ingenious solution to the perennial Japanese problem of lack of space. In their previous house, the family appropriated the roof as an informal outdoor terrace, extending their living area.

When they came to commission a new dwelling from the young partnership of Takaharu and Yui Tezuka, the notion of the roof as an external room became the starting point for the design. Hadano is about one hour by train from Tokyo and despite its suburban character retains some older historic parts.

The house occupies a corner plot with good views of Mount Kobo across a valley to the south. The single storey pavilion-like volume is compactly organized, with cellular bedrooms, bathroom, kitchen and study spaces flanking the main living area.


Lightweight sliding partitions separate these more private areas from the main space, so that if family circumstances change, then the interior can be easily reconfigured. Overlooking a small garden, the south side is fully glazed, with a narrow veranda running along its length. The main street facade is composed of austere planes of raw concrete.

Interiors are luminous and uncluttered, lined with panels of structural plywood. The overall sensation is rather like being inside a musical instrument. But it is the roof that commands most attention. Floating like a broad-brimmed hat over the house it forms a generous, multifunctional extension to the living space.

Gently inclined (at a pitch of 1 in 10), it acts as an outdoor deck, equipped with a seating area (enclosed by a low wall), kitchen and shower. A series of ladders and skylights connect the roof with the rooms below, so that each family member has their own means of access to the deck, like rabbits bolting up and down from their individual burrows.

Supported on slim laminated timber columns, the oversailing roof acts like a two-way spanning flat slab. Two double-skinned layers of structural plywood panels enclose a gridded core of 105mm square section timber members. This reduces the depth of the structure and gives the roof an elegantly thin profile.


Although the distinct lack of a handrail may induce palpitations in district surveyors and anyone with young children, the family seem entirely at ease with the roof-as-room arrangement, shinning nimbly up and down their ladders to eat, play, shower, sunbathe, converse, contemplate the view and even practise musical instruments.

Their former house had a smaller and steeper roof, so in this respect, the new purpose-designed deck is a much more practical proposition. Despite being dependent on the agility of its occupants and the clemency of the weather, this little house shows what can be achieved with a minimum of resources and a slightly unconventional architectural imagination.

Architect Tezuka Architects, Tokyo
Structural engineer Masahiro Ikeda
Photographs All photographs by Katsuhisa Kida except no. I which is by Shinkenchiku-sha

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