NCC 2022 · Volume Two
NCC 2022 Volume Two 10.8.3 - Calculator
Calculates roof ventilation requirements at high level and at eave (applicable to builds in climate zone 6, 7 & 8)
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Roof Space Ventilation
Enter the roof dimensions below to calculate the required open areas for compliant installations in applicable zones.
Longest horizontal dimension of the roof.
▶ Click to see 10.8.3 applicable climate zones
Under NCC 2022 Condensation Management provisions, roof space ventilation is a mandatory requirement for buildings located in Climate Zones 6, 7 and 8 only. If your project falls within any other climate zone, roof space ventilation is not required under these regulations. To confirm your climate zone, check which climate zone you're in here.
See Calculation Table ▾
| Roof Pitch | Eaves Open Area | High Level Open Area |
|---|---|---|
| Under 10° | 25,000 mm²/m (two opposing ends only) | Not required |
| 10° – 15° | 25,000 mm²/m | 5,000 mm²/m |
| 15° – 75°, Non-Cathedral Ceiling | 7,000 mm²/m | 5,000 mm²/m |
| 15° – 75°, Cathedral Ceiling | 25,000 mm²/m (7,000 + 18,000) | 5,000 mm²/m |
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