1. Material acceptance checklist
- Rebar: lot number, mill certificate (composition), diameter and count
- Concrete: delivery slip, design strength, mix-design sheet, slump value at pour
- Windows: serial number, glass spec, thermal performance
- Timber: moisture under 15%, JAS certification mark
2. Pre-cover-up inspections — non-negotiable
Three stages must be stopped and inspected before they're covered:
- Rebar → before the concrete pour
- Waterproofing → before screed and finish
- Plumbing and electrical → before drywall or render
3. The role of construction photos
10+ photos at each hidden stage. "If a question arises later, the photos answer it." Rebar shots include a tape for spacing and cover; waterproofing shots capture every joint and termination.
4. When something fails
Rebar spacing off, concrete strength under spec, a tear in the waterproofing. Light defects get repaired; serious defects get redone. The compass is always "what does this do in 30 years?"
5. Independent inspections
Beyond the supervising architect, a third-party inspection on structure, waterproofing, and insulation costs around JPY 200–400K — and pays back many multiples in long-term peace of mind.
Hidden work is invisible after handover. Photos and inspection records become the only honest history of the house.