Roof Pitches

Solutions for all roof designs

Calculated, continuous, unimpeded passive ventilation is a critical ingredient in the essential ventilation of a building. Using tried and tested international proven best practice, VENT Systems Airflow calculations are determined by the pitch and type of roof.

National Construction Code Vol 2, Part 3.8.7.4.b requires:

  • Traditional Roof Pitches >22° require a calculated airflow of 10,000mm² per linear metre or 1/300:
    • Product combination – G1200N and G502
  • Traditional Roof Pitches >30° require a calculated airflow of 10,000mm² per linear metre or 1/300:
    • Product combination – G1200N, G502 and RV10P/DT
  • Traditional Roof Pitches <22° require a calculated airflow of 25,000mm² per linear metre or 1/150:
    • Product combination – G2500N, G502
  • Cathedral Roof Pitches any degree pitch require a calculated airflow of 25,000mm² per linear metre or 1/150:
    • Product combination – G2500N, VB20 and RV10P/DT (Pitched) or AB20/DT (Mono Pitched)

Control of Condensation and Mould in Tasmanian Homes (CBOS vs 2):

  • Traditional Roof Pitches >16° require a calculated airflow of 10,000mm² per linear metre or 1/300:
    • Product combination – G1200N and G502
  • Traditional Roof Pitches >30° require a calculated airflow of 10,000mm² per linear metre or 1/300:
    • Product combination – G1200N, G502 and RV10P/DT
  • Traditional Roof Pitches <16° require a calculated airflow of 25,000mm² per linear metre or 1/150:
    • Product combination – G2500N, G502
  • Catherdral Roof Pitches  any degree pitch require a calculated airflow of 25,000mm² per linear metre or 1/150:
    • Product combination – G2500N, VB20 and RV10P/DT (Pitched) or AB20/DT (Mono Pitched)

When considering passive ventilation consideration should be given to other Australian Standards for example AS3959 for buildings in bushfire zones.

Mono Pitch Cathedral Roof, any degree pitch

Roof Ventilation option using the VENT Systems Over Fascia VENT (G2500N), VENT Systems Vented Batten (VB20), VENT Systems Apron Vent (AB20/DT) and VENT Systems Eaves Comb Filler (G1275) is also fixed as shown to prevent bird ingress and nesting insects.

This system will provide the recommended continuous airflow of 25,000mm2 per linear metre or 1/150.

Pitched Cathedral Roof, any degree pitch

Roof Ventilation option using the VENT Systems Over Fascia VENT (G2500N), VENT Systems Vented Batten (VB20), VENT Systems Ridge Vent (RV10P/DT) and VENT Systems Eaves Comb Filler (G1275) is also fixed as shown to prevent bird ingress and nesting insects.

This system will provide the recommended continuous airflow of 25,000mm2 per linear metre or 1/150.

Traditional Roof Pitch <22° (16° CBOS)

Roof Ventilation option using the VENT Systems Over Fascia VENT (G2500N), VENT Systems Roll Panel Vent (G502) and VENT Systems Eaves Comb Filler (G1275) is also fixed as shown to prevent bird ingress and nesting insects.

This system will provide the recommended continuous airflow of 25,000mm2 per linear metre or 1/150.

Ridge ventilation is required for roof spans greater than 10m and whilst not essential ridge ventilation can be applied to smaller spans.

Trussed Roof >30°

Roof Ventilation option using the VENT Systems Over Fascia VENT (G1200N), VENT Systems Roll Panel Vent (G502), VENT Systems Ridge Vent (RV10P/DT) and VENT Systems Eaves Comb Filler (G1275) is also fixed as shown to prevent bird ingress and nesting insects.

This system will provide the recommended continuous airflow of 10,000mm² per linear metre or 1/300.

Whilst option for traditional roof pitches <30°, ridge ventilation is essential for traditional roof pitches >30°

Traditional Roof 22°- 30° (16° – 30° CBOS)

Roof Ventilation option using the VENT Systems Over Fascia VENT (G2500N), VENT Systems Roll Panel Vent (G502) and VENT Systems Eaves Comb Filler (G1275) is also fixed as shown to prevent bird ingress and nesting insects.

This system will provide the recommended continuous airflow of 10,000mm2 per linear metre or 1/300.

Ridge ventilation is required for roof spans greater than 10m and whilst not essential ridge ventilation can be applied to smaller spans.

Traditional Mono Pitch Roof

Roof Ventilation option using the VENT Systems Over Fascia VENT (G2500N or G1200N), VENT Systems Roll Panel Vent (G502), VENT Systems Apron Vent (AB20 OR AB20DT) and VENT Systems Eaves Comb Filler (G1275) is also fixed as shown to prevent bird ingress and nesting insects.

  • For roof pitches >22° (>16° CBOS) apply the G1200N This system will provide the recommended continuous airflow of 10,000mm2 per linear metre OR 1/300.
  • For roof pitches <22° (<16° CBOS) apply the G2500N This system will provide the recommended continuous airflow of 25,000mm2 per linear metre OR 1/150.