The Round Back Static Vent with Curb Mount Flange is 12 inches in diameter with a 2 inch tall collar. In other words, this vent has 2 inches of clearance between the base and the inner louvers. The model RBV-12-C2-CMF has 113 inches of net free area (NFA) and comes with a 14” x 14” square curb mount flange.
The Round Back Vent removes hot air in the summer and moisture from the attic in the winter for year-round ventilation on low slope or flat roofs. This roof vent is engineered with a curb mount flange which allows for easy access to the attic or duct below. In other words, the flange is designed to fit over roof curbs or an existing base of the same diameter. As a result, this gives the vent head extra clearance allowing for installation in all climate zones.
To determine the number of vents you may need, see our Vent Calculator.
However, if you are looking to ventilate a duct, please see our Round Back Roof Jack for vents with a tailpipe adapter. On the other hand we also have Static Vents with flat flanges to be installed on roofs with a pitch of 3/12 or greater.
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 6 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.
Our Round Back Vents have the power to withstand hurricane force winds. See some of our customer feedback.
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.