How Many Roof Vents Do I Need

For example if you have 1200 square feet of attic space you should need at least 4 air vents to ensure proper ventilation.

How many roof vents do i need.

Keep in mind you should always consult with a professional roofing company when determining how many air vents your roof should have. They should be divided equally between inlet and outlet vents and they can be used in any combination that will work with your roof s design. The net free area nfa rating indicates the amount of space each roof vent covers. Near ridge of the roof.

The rule of thumb used to determine the number of roof vents to install is one for every 300 square feet of attic area if your attic has a vapour barrier and one for every 150 square feet of attic area if the attic does not have a vapour barrier. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. You will need to have 1 square foot of vent area for every 150 square feet of attic space. You ll need the square footage of your attic to calculate the number of roof vents that you should need.

Always have a balanced ventilation system. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. How many vents will my house need. And this guideline you ll need a minimum of.

Some local building codes carry special considerations that take precedence. To calculate the number of 750 vents needed divide 480 by 50 to get 9 6 vents. So if your attic is 450 square feet you will need 3 square feet of vent space evened out throughout the entire space and divided equally between inlet and outlet vents. Fan calculation as a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space.

In no case should the amount of exhaust ventilation exceed the amount of intake ventilation. Because you always want your intake nfa to meet or exceed the amount of exhaust nfa we will take the amount of exhaust provided and divide by the nfa rating of the deck air.