Seismic Standards In Japan
Japan revised its seismic building standards in 1981 under the Building Standards Act (建築基準法). This introduced the “new seismic standard” (新耐震基準), replacing the previous “old seismic standard” (旧耐震基準). The distinction is based on the building confirmation approval date (建築確認): before June 1981 means old standard, after June 1981 means new standard.
Under the old standard, buildings were primarily designed to withstand moderate earthquakes. The new standard requires buildings to withstand major earthquakes without collapse, even if damage occurs.
Why This Matters
- Financing: many banks are more conservative with pre-1981 properties, particularly for non-resident buyers.
- Resale: buyer demand is generally stronger for post-1981 buildings, affecting liquidity.
- Risk perception: older buildings are typically viewed as higher risk, even if well maintained.
Apartments Vs Houses
Apartments (RC / SRC) depend on overall building structure, seismic retrofitting (耐震補強), management, and maintenance history. Wooden houses depend more heavily on structural details, bracing, wall balance, and whether they meet the later 2000 standard.
Practical Takeaways
- Post-1981 buildings are generally easier to finance and resell.
- Pre-1981 properties require closer evaluation.
- Structure type matters as much as age.
- Renovation or reinforcement can change the risk profile.
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