AI Construction Cost Estimator
for Japan

Over 90% of Japanese detached houses use zairai kōhō, a traditional wood post-and-beam framing method distinct from Western platform framing — but the residential construction market itself is dominated by large turnkey 'housemaker' companies (Sekisui House, Daiwa House and similar), who quote a single all-in price per tsubo (a traditional unit, about 3.3 square metres) rather than an itemized material takeoff.

Because pricing here is bundled into a turnkey housemaker contract rather than broken into a public per-item schedule, real construction cost data for Japan is genuinely harder to source independently than in markets with a government-published rate schedule or an established quantity-surveying tradition — a real, disclosed limitation, not something worth glossing over with an invented figure.

Japanese lumber sizing conventions also differ from the inches-based sizing used in North American wood-frame estimating, which is part of why applying a US-style board-feet takeoff formula directly to a Japanese house isn't something this platform does without saying so.