The 4 inch Round Back Static Roof Vent is 4 inches in diameter and has 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-4-C2 has 12 inches of net free area (NFA) which means each vent will ventilate 50 square feet of attic space.
The 4 inch roof vent is ideal for roofs with a 3/12 to 12/12 roof pitch. For a pitch of 3/12 or greater, install this vent no more than 3 feet from the ridge of the roof. Doing this will enable you to install your static vent in climate zones 1-5.
However, if installations are 18 inches or less from the ridge of the roof, this vent is suitable for all climate zones.
The 4 inch static roof vents will work in conjunction with bathroom fans and range hoods.
The vent lid is one piece of spun aluminum that prevents rain and snow from entering the attic. The round design is aerodynamic to withstand wind pressure exceeding 200 mph. All Round Back roof vents are resistant to corrosion and will remain rust free for the life of the roof.
The inner louvers of the roof vent keep insects and animals from entering the attic. The louvers also allow the air to flow freely to the outside.
This 4 inch roof vent is great for residential roof applications because of its low profile. In addition, these vents can be painted to match the color of asphalt shingle roofs.
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.
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.