Condensation Management
2024-03-27
Source: Passive House Building Science Details
In a Perfect Wall assembly all insulation is on the exterior.
However when mixing interior and exterior insulation it's important to maintain ratios between interior and exterior insulation.
However when mixing interior and exterior insulation it's important to maintain ratios between interior and exterior insulation.
The following table shows the assembly ratios that should be kept. One can always increase the % on the exterior but not go higher on the inside!
2x4 Framing
| Climate Zone | Minimum R | % Exterior |
|---|---|---|
| 4C | 2.5 | 16% |
| 5 | 5.0 | 28% |
| 6 | 7.5 | 37% |
| 7/8 | 10 | 43% |
2x6 Framing
| Climate Zone | Minimum R | % Exterior |
|---|---|---|
| 4C | 3.75 | 16% |
| 5 | 7.5 | 28% |
| 6 | 11.25 | 37% |
| 7/8 | 15 | 44% |
Fins Concealed Cavitites
If these are thin they can still create condensation issues as there is more heat leaving then getting into the space.
Keep insulation / air barrier away from these spaces and add them outside of it.
