The 4 inch Aura Gravity Ventilator is 4 inches in diameter and has an 8 inch tall collar. The model number is AV-4-C8 and has 12 inches of Net Free Area (NFA). All 4 inch gravity ventilators come with a standard 10″ x 10″ square flange flashing.
This Gravity Ventilator is typically for low slope or flat roof ventilation because of its tall collar. However, if the roof is a low slope the vent should go on the upper portion of the roof. This particular roof vent can go on a 0/12 to 5/12 pitch roof in all climate zones. See the installation guides for help installing.
The Aura Gravity Ventilator works like a roof turbine but with no moving parts.
Aura Gravity Ventilators rely on the Venturi Effect when the wind blows against the outer louvers. As a result, this creates an upward draft allowing air to freely flow in and out of the vent.
Even the smallest breeze can create exhaust ventilation to draw out air from the gravity vent. Therefore, wind speeds of 11 mph for a 4 inch Gravity Ventilator produces 62 CFM of air exhaust for attic ventilation.
For any questions please see the frequently asked questions page. If you still have questions, email the sales team at [email protected] or call 845-565-7770. If you are looking to determine the pitch of your roof, see the Roof Pitch Diagram.
The diameter size of all roof vents determines the Net Free Area, also known as the "NFA". NFA is the measured amount of opening each vent offers at each specific size. to be available for venting air through a specific vent size. The calculator below will find the overall number of vents needed to effectively ventilate the targeted attic space.
Once you have the area, the numbers shown below are the number of vents of that size which would ventilate the specified area with both 1/300 and 1/150 rule.
The roof vent calculation values shown above are for the exhaust portion of the roof. The same amount of net free air inches is needed for air intake as well. Proper roof ventilation consists of 50% air exhaust and 50% air intake.