Roof Ventilation Products

There are many product options which will provide passive ventilation for new build and existing homes. As this is a relatively new concept to New Zealand, we have recommended the following range of product options as a simple and effective guideline.

The products have been selected to achieve the recommended airflow for roof pitches above 15° (10,000mm2 lin/m) and below 15° (25,000 mm2 lin/m).

Primary roof ventilators fit externally within the eaves, usually within either the soffit board or fascia board, and provide an appropriately sized opening for air to flow into and out of the roof space. They incorporate rows of slots or holes which are large enough to allow the required volume of air to flow freely without danger of blockage by dirt, dust, cobwebs etc but are small enough to prevent the entry of vermin or large nest-building insects such as bees and wasps. All ventilators have 3.5 - 4mm wide slots or holes in accordance with recommendations.

Secondary roof ventilators fit higher up within the eaves, usually between the rafters above the wall plate position. They hold down the quilt of roof insulation material and prevent it from restricting the flow of air to and from the primary roof ventilator.

In most cases it is essential that both primary and secondary roof ventilators are used in conjunction with each other in order to provide a reliable ventilation system.

Roof pitch below 15

Recommended Products

A 'Cold Roof' with a pitch of less than 15° requires 25,000mm2/m of continuous airflow at fascia or soffit level. The most discreet product to achieve this is by using the Over Fascia Vent (G2500N) which is compatible with most steel fascia systems and timber.

The Eaves Vent (EV25) is also recommended here to ensure continuous airflow.

Location
Over-Fascia Vent
Eaves Vent
Ridge Vent
Fascia
 
 
Eaves
 
 
Ridges
 
 
N/A

Roof pitch between 15-35

Recommended Products

A 'Cold Roof' with a pitch of 15° - 35° requires 10,000mm2/m of continuous airflow at Fascia or soffit level. The most discreet product to achieve this is by using the Over Fascia Vent (G1200N) which is compatible with most steel fascia systems and timber.

The Eaves Vent (EV25) is also recommended here to ensure continuous airflow.

Location
Over-Fascia Vent
Eaves Vent
Ridge Vent
Fascia
 
 
Eaves
 
 
Ridges
 
 

Roof pitch over 35

Recommended Products

A roof pitch more than 35° requires 10,000mm2/m of continuous airflow at Fascia or soffit level. The most discreet product to achieve this is by using the Over Fascia Vent (G1200N) which is compatible with most timber & steel fascia systems.

The Eaves Vent (EV25) and Ridge Vent (RV10P) are also recommended here to ensure continuous airflow.

Location
Over-Fascia Vent
Eaves Vent
Ridge Vent
Fascia
 
 
Eaves
 
 
Ridges
 
 

Mono pitch Roof below 15

Recommended Products

Warm Roof

For Mono- pitch roofs of 15° or less, 25,000mm²/m of airflow is required at fascia/soffit level to ensure a cross flow of ventilation above the insulation. An G2500N would be suitable at fascia/soffit level and a VB20 would allow the warm air to be released at the top.

Location
Over-Fascia Vent
Eaves Vent
Ridge Vent
Fascia
 
 
Eaves
 
N/A
 
Ridges
 
 

Abutment Roof

Recommended Products

For an Abutment roof of less than 15°, the Over Fascia Vent (G2500N) would provide 25,000mm²/m of airflow at Fascia level and for pitches greater than 15° the G1200N would provide 10,000mm2/m. The Eaves Vent (EV25) would also be recommended to ensure continuous airflow. The Abutment ventilation can be achieved by using a G1200N

Location
Over-Fascia Vent
Eaves Vent
Ridge Vent
Fascia
<15° = G2500N
> 15° = G1200N
 
 
Eaves
 
 
Ridges
 
 

Flat Dormer Roof

Recommended Products

Dormer windows, fire barriers and pitch changes for example, create separate voids within the roof space. Ventilation must be maintained to these areas at high and low level as illustrated. The same rules apply as previous roof scenarios with the Over Fascia Vents (OV25), Eaves Vents (EV25) and the Ridge Vent (RV10P) for continuous airflow.

Location
Over-Fascia Vent
Eaves Vent
Ridge Vent
Fascia
 
 
Eaves
 
 
Ridges
 
 

All products available through your preferred supplier:

Bunnings Warehouse
ITM
Steel & Tube
Metalcraft Roofing
Mitre 10 Mega
Carters - Your Building Partner
Calder Stewart
Placemakers - Know how can do
Roofing Industries