The 18 inch Aura Gravity Retrofit Vent is for replacing existing attic vents. The AV-18-RF is 18 inches in diameter and has 254 inches of Net Free Area (NFA).
This roof vent will fit over an existing base of the same diameter. It is a perfect replacement for turbine vent heads. Turbine vents frequently stop turning entirely due to corrosion. However, our Gravity Retrofits are made of durable rust-free aluminum.
The Aura Gravity Retrofits will fit over an existing base of the same diameter. This allows for easy installation without damaging the roofing material. The vent removes heat from the attic in the summer and moisture in the winter allowing for proper ventilation. This retrofit comes in an array of sizes to fit all roofing needs.
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 air out of the gravity vent. In addition, the round design is aerodynamic to withstand wind speeds up to 200 mph. This is much more efficient compared to a typical wind turbine vent, which is open to the sky; Thus allowing rain and snow to get inside when it is not in motion.
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.