Concrete casket: this family house maximizes a tight urban site to create a dramatic internal realm

Architectural Review, The, Jan, 2005 by Phoebe Chow

When designing houses for their own use, architects are usually more able to succumb to the pleasures and perils of self-expression with sometimes intriguing, sometimes dismaying results. This new house in Kobe falls into the former category. Building any sort of dwelling in Japan's overcrowded cities is a challenge, met here with no little ingenuity by Hiroaki Ohtani, who has designed and built a house for himself and his family in the heart of Kobe. Ohtani found a characteristically tight site, only 33sqm in footprint and barely 3m wide, hemmed in between two existing houses. The lack of space and limited access precluded the use of elaborate construction equipment, so the programme assumed an even more formidable dimension.

Ohtani's response was to create an exquisitely ascetic concrete and timber casket that slots precisely into the cramped space. Within this domestic receptacle are spaces for study, sleeping, washing, living and dining stacked up with the precision of a Chinese puzzle and linked by disarmingly vertiginous flights of stairs seemingly hijacked from the illusionistic imagination of M. C. Escher.

To maximize every scrap of space, the house is set back slightly from the street, creating a tiny enclosed entrance patio planted with a single tree, signifying the boundary of a private domain. Horizontal concrete slats wrap around the patio and frame a huge glazed opening cut into the street frontage. The slatted fence and tree conspired to screen the interior of the house from the attentions of the street.

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The sleeping floor is raised slightly above street level with a dining cum study room and bathroom sunk slightly below it. The topmost floor contains an integrated living and kitchen space, its soaring volume illuminated by the glazed street facade and an opening cut into the roof above the staircase that filters shafts of light into the long deep plan. A smaller (but steeper) secondary staircase leads up from the living area to a roof terrace.

Because site conditions limited mechanical construction, Ohtani used pre-stressed concrete strips laid horizontally by hand to form the enclosing walls. The technique recalls log cabin building (walls are constructed with no vertical members) and traditional Japanese structures which employ horizontal strips of timber. Stair treads, shelves and other fixtures and fittings are simply slotted in between the precast members.

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Within this slatted concrete box, everything is pared down to its utter minimum. Stairs, for instance, are simply a series of timber treads without the pesky encumbrance of risers, balustrades or handrails. This certainly contrives to open up the interior and encourage spatial interpenetration, but vertical circulation is not for the faint-hearted (Ohtani and his wife have a six year old daughter who must be especially fearless).

Warm timber floors and furniture set off the slightly austere concrete walls, so the entire house has a powerful elemental quality derived from a limited palette of materials animated by the play of light. Ohtani consciously rejects the clutter of the world; as he puts it 'Lack of things can create a rich lifestyle', and his admirable if somewhat rigorous personal proscriptions include not owning a car, television, microwave, curtain, fax and 'a large refrigerator'. His ingenious little house, which in its use of space and materials has lessons for building on tight urban sites everywhere, is an eloquent manifestation of this philosophy.

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