How Many Roof Vents Needed

Choosing round soffit vents for.

How many roof vents needed.

1 square foot of ventilation for every 300 square feet of space. And this guideline you ll need a minimum of. Near ridge of the roof. 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.

Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. In no case should the amount of exhaust ventilation exceed the amount of intake ventilation. You will need to have 1 square foot of vent area for every 150 square feet of attic space. 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.

For example if you have 1200 square feet of attic space you should need at least 4 air vents to ensure proper ventilation. If the slope of your roof is greater than 6 12 you will need more ventilation to reflect the extra volume of attic space. 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. For pitched roofs with vapor barriers.

For the number of soffit vents in the example divide 8 square feet of ventilation needed by 0 5 for the number of rectangular vents required 16 in the example. Basic attic ventilation principal is to keep that unused section of our house as cool as possible critical condition during the cold season dividing amount of the roof upper and lower vents 50 50. How many vents will my house need. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation for every 300 square feet of attic floor space evenly split between intake and exhaust.

1 square foot of ventilation for every 150 square feet of space. Always have a balanced ventilation system. Based on your 1100 sq. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space.

The net free area nfa rating indicates the amount of space each roof vent covers.