located in a coastal town in hiroshima, japan, the knothole house by ICADA incorporates a thin and lightweight timber roof that resembles a starry sky thanks to the numerous skylights punctured on its surface
the 20mm holes are part of the laminated timber panels used on the project, which are intermediate, semi-finished goods taken from the production process of CLT, and though the symbol of poverty in japanese timber building tradition, in this case, they offer a rich spatial experience.ICADA has built the knothole house for a couple, a painter and his wife, who wanted a timber annex beside their concrete house, with functions such as an extra living room, kitchen, bathroom, small workshop and garage. due to a tight budget, the ultra-light timber structure has been designed with the use of very low cost materials, such as laminated timber panels, with just 3 cm thickness, reinforced by hemp rope ties to restrain the deformation. without beams, purlins and rafters, its thin and lightweight timber roof spans four meters, covered by translucent polycarbonate panels that let light come into the house through the numerous knotholes. hemp ropes are used as a tension materials, which are cheaper than steel cables, and imply the character of the site as fisherman’s village, according to the studio.
textile walls with insulation are partly applied for thermal comfort on the exterior, while timber walls are made from the remnants of the roof panels. material choices have been made to contribute to creating the house within the tight budget, including: exposed structures, backing materials and pipe works within the interior’ the garage’s floor left bare instead of covering it with concrete; and a textile curtain used for pastoral works, applied as the garage door.
name: knothole house
architect: ICADA/ masaaki iwamoto + nariaki chigusa
location: fukuyama, hiroshima, japan
program: private house
principal architects: masaaki iwamoto, nariaki chigusa
structural engineer: mika araki
contractor: mimachi komuten
GFA: 91.35 m2
footprint: 91.35 m2
site area: 999.82 m2
maximum height: 3.35 m
construction cost: 73,000 USD