Roof Vent Free Air Comparison
The table below shows the calculated free air area for our roof ventilator range,
including the standard open vent area and the adjusted free air area when fitted
with BAL-40 compliant 1.7mm perforated mesh.
Calculation basis: BAL-40 mesh airflow is calculated using an estimated
45% open area for 1.7mm perforated metal. Final airflow may vary slightly depending
on the exact mesh pattern, material and installation method.
| Vent Type | Roof Type | Opening Dimensions | Free Air No Mesh | Free Air With BAL-40 Mesh | Material / Finish |
|---|---|---|---|---|---|
| Universal Tile Vent | Concrete tile roofs | 260mm × 25mm | 6,500mm² / 65.0cm² | 2,925mm² / 29.3cm² | Roof colour finish |
| Terracotta 250 Vent | Terracotta tile roofs | 170mm × 35mm | 5,950mm² / 59.5cm² | 2,678mm² / 26.8cm² | Roof colour finish |
| Terracotta 280 Vent | Terracotta tile roofs | 200mm × 35mm | 7,000mm² / 70.0cm² | 3,150mm² / 31.5cm² | Roof colour finish |
| Smoothline Vent | Corrugated roofs | Trapezoid 390 / 260 × 40mm | 13,000mm² / 130.0cm² | 5,850mm² / 58.5cm² | Zincalume |
| Galvanised Smoothline Vent | Corrugated roofs | Trapezoid 390 / 260 × 40mm | 13,000mm² / 130.0cm² | 5,850mm² / 58.5cm² | Galvanised steel |
| Trimdek Vent | Trimdek roofs | Trapezoid 405 / 360 × 40mm | 15,300mm² / 153.0cm² | 6,885mm² / 68.9cm² | Roof colour finish |
| Spandek 700 Series Vent | Spandek 700 roofs | Trapezoid 375 / 315 × 40mm | 13,800mm² / 138.0cm² | 6,210mm² / 62.1cm² | Roof colour finish |
| Klip-Lok Vent | Klip-Lok roofs | Trapezoid 420 / 335 × 70mm | 26,425mm² / 264.3cm² | 11,890mm² / 118.9cm² | Roof colour finish |
Trapezoid calculations use the formula: ((base + top) ÷ 2) × height.
BAL-40 mesh airflow is calculated as gross free air × 0.45.
BAL-40 Mesh & Airflow Options
Many roof vents on the market are supplied without BAL-40 compliant mesh. Our vents are supplied with BAL-40 style 1.7mm perforated mesh for added ember protection where
bushfire performance is required.
Where BAL-40 level fire protection is not required, the mesh can be removed, modified or
changed to suit the project requirements, allowing significantly increased airflow through
the vent. Always check local building requirements, bushfire rating requirements and
installer recommendations before modifying any ventilation product.