How Many Roof Vents Do I Need

Choosing round soffit vents for.

How many roof vents do i need.

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. For example if you have 1200 square feet of attic space you should need at least 4 air vents to ensure proper ventilation. 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. In no case should the amount of exhaust ventilation exceed the amount of intake ventilation.

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. You ll need the square footage of your attic to calculate the number of roof vents that you should 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. You will need to have 1 square foot of vent area for every 150 square feet of attic space.

Fan calculation as a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. Near ridge of the roof. And this guideline you ll need a minimum of. Some local building codes carry special considerations that take precedence.

The net free area nfa ratingindicates the amount of space each roof vent covers. Based on your 1100 sq. Always have a balanced ventilation system. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet.

How many vents will my house need.