Many months of planning and design have gone into these almost-final construction drawings.
Key features are:
- The avoidance of thermal breaks in the roof and floor.
- Minimal thermal breaks in the walls (1.8m spans).
- Minimum 120mm rigid foam insulation in walls, 150mm in roof and floor. (R38 walls & R46 roof/floor)
- Exposed timbers where desired inside and where not up to 240mm of rigid foam insulation in walls and 270 in roof/ceiling.
- Excellent ventilation of structural roof, wall and under floor spaces.
- Thick foundation platform (240mm), well over building regulations for earthquake-prone Japan.
- Exterior wall foundation overhangs.
- Three vapor barriers in each wall, four in floor, five in roof (due to the layers of aluminium backing on the insulation panels and the house wrap).
- Outer skin of plywood should almost double the earthquake rating of the timber frame which is already over specification with bracing.
- Inside layer of plasterboard adds to insulation and sound barrier levels.