Dezeen Magazine

International Royal Architecture aims for spaciousness with minimal KKZ House interior

Japanese firm International Royal Architecture (IRA) minimised partitions and balustrades inside this split-level house in Tokyo to make the interior feel as spacious as possible (+ slideshow).

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Located on a small corner plot in Setagaya, KKZ House was designed by IRA to provide a generous three-storey residence for a family.

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To achieve this, the architects developed a split-level plan featuring several double-height spaces. This created a basement floor that boasts clerestory windows, as well as a pair of upper levels with floor slabs that don't meet all four walls.

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"Connecting these floors with voids, which run through the entrance hall and above the kitchen, makes the residence so spacious," said the architects in a statement.

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Externally the house appears as a rectilinear box with a white-rendered surface. One corner looks as if it has been sliced away, leaving a glazed recess that accommodates the building's entrance.

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Inside, a mid-level platform leads up to a simple living room and kitchen on the middle floor, or down to a basement level proposed as a children's bedroom. Simple metal railings provide the only balustrades, so residents can easily clamber or jump between these floors.

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A master bedroom is located on the uppermost storey and features glazed partitions on two ends, allowing light to filter through from the room below.

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The architects chose 180-millimetre-thick laminated veneer lumber (LVL) beams – a kind of engineered timber similar to plywood – to create solid floor slabs that are supported by cantilevers, rather than with columns.

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"With this simultaneous design of the floor and the ceiling as a single slab, though simple it is, one can feel the presence of the structural materials," said the architects.

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A variety of different materials were used to provide floor and wall finishes throughout the building. These vary from poured concrete and wooden panelling, to dark tiles and basic white plaster.

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The house also features a secluded roof terrace, as well as a series of small windows that can be camouflaged behind plain white shutters.

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International Royal Architecture was founded in 2010 by architects Akinori Kasegai and Daisuke Tsunakawa. Past projects by the studio include a house shaped like an arrow.

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Basement plan - click for larger image
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Ground floor plan - click for larger image
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First floor plan - click for larger image
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Section - click for larger image