[2025] Defect Rate in Home Inspections During New Detached House Construction

Sakura Office Co., Ltd. (Shibuya-ku, Tokyo; President: Rinka Onishi), "The Real Estate Master," which provides comprehensive real estate consulting and home inspection (housing diagnosis) services for individuals, and consulting services for condominium management associations, is pleased to report the aggregated inspection defect rates for the five main items in new detached house construction home inspections conducted by Sakura Office in 2025, categorized by company size.

Defect Rate in Home Inspections During New Detached House Construction by Company Size

【Survey Overview】

・Survey Period: March 2026

・Survey Organization: Sakura Office Co., Ltd.

・Survey Target: 625 properties where Sakura Office conducted home inspections (third-party inspections) during new construction between January and December of both 2024 and 2025.

Overall Decrease in Defect Rate

The defect rate in 2025 has relatively decreased compared to the previous year, indicating an overall improvement in the construction quality of new buildings. In particular, the defect rate for "structural hardware inspections" has decreased by over 20% for major and semi-major companies, and by over 10% for small and medium-sized companies.

Structural hardware refers to fittings used to firmly connect structural members such as pillars, beams, and foundations, which form the framework of a house. When a large force such as an earthquake is applied, if each member is not securely fixed, there is a risk of joints coming loose and collapse. In Japan, an earthquake-prone country, meticulous attention is required for construction quality related to seismic resistance, so this improvement in figures can be considered a welcome step forward for the entire industry.

Defect Rate for External Sheathing Shear Walls

On the other hand, although not included in the five main items, among inspections related to seismic resistance, the defect rate for "external sheathing shear walls (boards installed on the inside of exterior walls to enhance seismic resistance)" remains high, exceeding 60% for major and small-to-medium companies, and over 40% for semi-major companies.

Furthermore, for "foundation rebar," also related to seismic resistance, while major and small-to-medium companies saw a significant decrease in their defect rates compared to last year, semi-major companies experienced a slight increase, and both semi-major and small-to-medium companies still have defect rates exceeding 50%. Therefore, construction quality related to seismic resistance remains one of the items that requires continued close attention.

Defect Rate for "Exterior Wall Waterproofing" Remains High Regardless of Company Size