Timber frame wall with ventilated timber cladding, 60 mm continuous wood-fiber board, 220 mm mineral wool between studs, airtight layer, 50 mm insulated service cavity, and 12.5 mm gypsum finish. Total build-up thickness (incl. ventilated zone and cladding): ~410 mm.

Meets low-energy to passive-house targets; very high thermal performance with robust moisture management (ventilated façade + vapor-open exterior, airtight interior). Suitable for temperate and cold climates; adaptable to humid subtropical zones with correct membrane specification.

📊 Thermal Performance

Rse = 0.04 m²K/W, Rsi = 0.13 m²K/W
ΣR (layers counted) = 9.014 m²K/W → R_total = 9.184 m²K/W
U = 0.109 W/m²K

1. External Timber Cladding — 25 mm

Softwood boards. λ ≈ 0.13 W/m·K.
R = 0.192 m²K/W (not included in U/R_total due to ventilated cavity separation).

2. Ventilated Cavity — 40 mm

Open, back-ventilated.
R = (ventilated) excluded from U/R_total.

3. Weather / Wind Barrier — 0.2 mm

Breathable WRB. Thickness negligible; thermal R ≈ 0 (excluded).

4. Wood-Fiber Board (continuous) — 60 mm

λ = 0.046 W/m·K → R = 1.304 m²K/W (counted).

5. Mineral Wool Between Studs — 220 mm

λ = 0.035 W/m·K → R = 6.286 m²K/W (counted).
Note: 220 mm insulation infill; calculation is 1D and does not reduce R for stud fraction.

6. OSB Sheathing — 12 mm

λ = 0.13 W/m·K → R = 0.092 m²K/W (counted).

7. Airtight / Vapor Control Layer — 0.2 mm

Membrane; thermal R ≈ 0 (excluded).

8. Service Cavity (insulated) — 50 mm

Mineral wool λ = 0.039 W/m·K → R = 1.282 m²K/W (counted).

9. Gypsum Board — 12.5 mm

λ = 0.25 W/m·K → R = 0.050 m²K/W (counted).