Daiwa House unit faked 816 ground-survey reports for 12 years until the ground sank

Daiwa Rantec, the Osaka-based Daiwa House Industry subsidiary that performs ground surveys for the group's housing work, disclosed on 24 July 2026 that its surveyors had fabricated parts of ground-survey reports for client sites. Four staff members at its Northern Japan sales office repeatedly processed test data or reused data from other sites instead of reporting what the soil actually showed, producing 816 improper reports between October 2012 and March 2025 — more than twelve years, mostly in the Tohoku region and Hokkaido.

The scheme surfaced physically, not procedurally. In May 2025, a client building on one of the subsidiary's reports had a paved road inside the site sink during construction. The investigation that followed traced the failure to the fabricated report underneath it, and then to a routine: surveys judged by workload rather than measurement, with figures massaged or borrowed wherever the field test was inconvenient.

Daiwa House said it would set up an external investigation committee to establish the full picture, with findings due in December 2026. The immediate question hanging over the disclosure is how many of the 816 sites hold homes whose foundations were sized against numbers nobody actually measured.

816 survey reports unreliable across Tohoku and Hokkaido from October 2012 to March 2025; re-surveys, remediation questions, external probe due December 2026.

Workload pressure did the corrupting: the Northern Japan office's small survey team prioritized processing volume, and a doctored report cleared a job far faster than a real field test.

The fabrication was deliberately boring — tweak a penetration value, copy a nearby site's dataset — so the reports looked routine and passed desktop review for years.

Nothing in the pipeline re-tested finished sites, so twelve years of reports were accepted at face value; the first audit that mattered was a driveway sinking.

A subsidiary's shortcut became a group problem: Daiwa House's pipeline depended on its in-house surveyor, so keeping reports flowing outranked questioning them.

A testing backlog without headcount turns quality control into fiction. When workload makes real field tests optional, a plausible report beats an honest delay.

Daiwa House has ordered an external investigation committee, with a full report targeted for December 2026, and the affected reports feed the same wave of construction-quality distrust that has already swept other Japanese builders. Clients on the 816 sites face re-surveys and remediation questions, and the case lands while regulators are tightening scrutiny of delegated ground surveys after a string of construction-data scandals across the industry.