FAQs – General:
What is Passive Ventilation?
Why do we need to passively ventilate?
Is it a proven solution?
What is the difference between mechanical and passive ventilation and is there a need to passively ventilate a mechanical system is installed?
Will passively ventilating a roof cavity compromise the thermal efficiency of my insulation?
Does every roof require passive ventilation?
How costly is it to passively ventilate my roof space?
FAQs – Product:
Does the VB20 sit on the top of building paper or under?
When constructing a typical cold roof using a single membrane it is recommended to create ventilation by placing the VB20 on top of the purlin UNDERNEATH the roofing membrane. If however a warm roof construction is being constructed using a double membrane application then the airflow needs to be created above the upper membrane whereby the VB20 is placed ABOVE the upper membrane.
What’s the gap between RV10P and Ridge cap?
In order to cover the aluminium soft edge it is recommended to make the ridge capping to a minimum of 250mm with a drop down of 15mm. This will ensure that the aluminium soft edge is covered.
Is RV10P tape supposed to protrude beyond the ridge cap?
What’s the deepest trough RV10DT can work on?
What over fascia vent do you apply to a roof of under 15°?
The G2500N is designed to allow a calculated airflow of 25,000mm² per linear metre into the roof cavity. The smaller or tighter the roof cavity the more airflow is required.
Is it better to ventilate through the soffit or over the fascia and do VENT offer soffit strip vent in their product range?
VENT is however currently in the design phase of a soffit strip which can easily be applied to both new build or existing buildings.
Do VENT products (RV10) perform well in strong wind areas?
All other VENT products have long history of use in countries with high wind zones comparable to those experienced in New Zealand.
Can G1275 stop rats?
The G1275 will however prevent birds and nesting insects from accessing and nesting in roofing profiles. At the same time it is designed to never block airflow, unlike some traditional foam products.
How close would you put G700 to each other?
For 10,000mm² per linear metre, recommended for trussed roof pitches above 15,° the spacings should 200mm apart
To achieve 25,000mm² per linear metre, recommended for all trussed roof pitched under 15° and any pitch skillion roof, the recommended spacings are at 86mm staggered centres. Yes, this is a large amount of vents however one must remember that we are trying to achieve ‘calculated’ and ‘continuous’ airflow. Sporadically placed vents will not adequately ventilate your roof cavity.
As an alternative both the G1200N and G2500N Over Fascia vents can be used.
Can the G1200N or G2500N VENT Over Fascia Vents be retrofitted?
Removing the roof in its entirety and raising the roof height is definitely the easiest way to retro fit the vents. However, if the roof is in place and you are simply attempting to install the vents, the lower portion of the roof cladding will need to be lifted and the over fascia vents be positioned on top of the fascia. Securing the Over Fascia Vents is ideally achieved by fixing through the top of the vents and into the timber or metal fascia. As the roof cladding will press own on the vent when in place using the correct plastic to timber or plastic to metal adhesive will hold the Over Fascia Vents in place.
For new build installations please refer to the VENT installation guide in our Resources page