The 3 inch Round Back Static Vent is 3 inches in diameter with a 4 inch tall collar. In other words, this vent has 4 inches of clearance between the base and the inner louvers. The model RBV-3-C4 has 7 inches of net free area (NFA) and comes with an 8” x 8” square flange.
For a pitch of 3/12 or greater, install 4 feet from the peak in climate zones 1-4. However, if the installment is less than 18 inches from the peak on a roof pitch of 4/12 or greater, this vent is suitable for all climate zones.
The 3 inch Round Back Vent is ideal for roofs with a 3/12 to 12/12 roof pitch.
To determine the number of vents you may need, see our Vent Calculator.
This static vent is ideal for venting out bathroom fans or range hoods. In addition, the round design is aerodynamic to withstand wind speeds up to 200 mph. The 3 inch Round Back Vent is great for residential roof applications because of its low profile. It can also be painted to match the color of the asphalt shingles.
AVP’s Round Back Static Vents are UL Listed and rated up to 50+ PSF or wind pressure above 200 MPH. Certified by Texas Department of Insurance, Florida State Approved & Conforms to the Standards of CALFIRE.
In addition, if you are looking to ventilate a duct, please see the Round Back Roof Jack for vents with a tailpipe adapter. On the other hand, AVP also offers Static Vents with curb mount flanges to go on roof curbs.
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.