The Round Back Vent works as both an exhaust vent and as an air intake vent. It removes hot air from the attic in the summer and moisture in the winter for year-round ventilation. 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. Because of the curb mount flange, this vent is primarily used on low slope or flat roofs.
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 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.
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.
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, pulldown to select the specific vent diameter to show 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.