1 Roof Condition
Slope ≥ 1:6 (2:12) with rafters or trusses → 1:300
2 Insulated Ceiling Area
m²
Total insulated ceiling area of the attic space
Required Unobstructed Vent Area (NFA)
— sq in
Enter ceiling area above
Ventilation Ratios — 9.19.1.2
| Roof Condition | Ratio |
|---|---|
| Standard pitch (≥ 1:6 slope) | 1 : 300 |
| Low-slope (< 1:6) or joist-framed | 1 : 150 |
NFA = Ceiling Area ÷ Ratio
NFA = net free (unobstructed) vent area
Ratio = 300 or 150 per Sec.9.19.1.2
Ratio = 300 or 150 per Sec.9.19.1.2
Clearance Requirements — 9.19.1.3
| Location | Min. Clearance |
|---|---|
| Insulation to sheathing (general) | 63 mm (2.5") |
| Eave baffles — air space | 25 mm (1") |
| Eave baffles — above insulation | 50 mm (2") |
Ceiling insulation shall not restrict airflow through roof vents or attic spaces. — Sec.9.19.1.3.(3)