aoyagi design tops 'house in iruma' with seven-meter-tall triangular attic space in japan

aoyagi design has topped ‘house in iruma’ with a seven-meter-tall triangular attic space formed by a truss of CLT panels. located in a residential area in the suburbs of saitama, japan, the two-story house is built for a couple and their child. the building comprises an open, bright ground level where all functions for daily life are located, and the triangular attic space, which has no fixed purpose. all images © takumi ota

aoyagi design has divided ‘house in iruma’ in two levels that differ in scale and function. the ground level consists of a bright, open space that encloses all daily functions, while the attic has not been assigned any fixed purpose. another point of contrast between the two levels is light and shadow, where the ground level is bathed in natural light, while the seven-meter-high attic space is engulfed in shadow.

through the central atrium, the attic’s darkness extends to the ground level, intermingling with its natural light. ‘this merging of light and shadow expands the space and blurs the boundaries of the quality of attic vs living,’ notes aoyagi design. the triangular attic is formed by a truss of CLT panels with a 90mm thickness, chosen as a response to exterior wind pressure. not only structurally functional, the panels also give beauty to the building, while the rich texture of the wood makes it unnecessary to install further interior finishes. the structure also eliminates the need for insulation due to the considerable thickness of the panels.

project info:

name: house in iruma

architect: aoyagi design

team: hajime aoyagi, ayaka aoyagi

structural engineer: HF architectural design – hiroshi fukuyama

location: saitama, japan