RC vs. wood — comparing Japan's two structural systems

1. Cost

Item	Wood	RC
Per-tsubo cost (shell)	JPY 0.7–1.2M	JPY 1.2–1.8M
Foundation	Standard	+30–50% (more rebar / concrete)
Design & supervision fee	8–10% of shell	10–12% of shell

RC runs roughly 1.5–2× wood. At the luxury end, with equivalent fit-out, RC is about 60–80% pricier in our experience.

2. Seismic performance

Since the 2000 code revision, both systems must withstand seismic intensity 6-strong to 7 without collapse. When designed properly, wood and RC perform equivalently. However, the felt vibration is smaller in RC, and interior damage tends to be lower.

3. Lifespan

• Wood: Statutory life 22 years, real-world 60–100 with proper maintenance (countless century-old kominka exist).
• RC: Statutory 47 years, real-world 60–100 (concrete carbonation is the controlling factor).

Wood does not have the short life the market imagines. Real-world durability tracks water management and termite control, not the material itself.

4. Insulation

Wood has lower thermal conductivity and reaches strong UA-value performance easily. RC's thermal mass shines when paired with external insulation: warm in winter, cool in summer.

5. Acoustics

RC wins decisively. Best for dense urban sites, road noise, home theatres, and musicians. Wood can be upgraded with resilient channels and acoustic boards, but only so far.

6. 30-year maintenance cost

• Wood: Repainting exterior and roof every 10–15 years — JPY 4–6M over 30 years.
• RC: Less frequent exterior repair, but waterproofing renewal and recoating — JPY 5–8M over 30 years.

Which to choose

Dense urban site, 3+ storeys, acoustic priority: RC. Suburban, thermal comfort, natural materials: wood. Mixed structures (steel, RC + wood hybrid) are real options too.

"Luxury equals RC" is a stereotype. Ashiya and Hokusetsu are full of exceptional wood-frame residences. Choose structure from the site and the brief, not from the price tag.