How Many Roof Vents Do You 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.

How many roof vents do you need.

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. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. Use the calculator below to find out how many exhaust and intake vents you will need on your house. Calculate 20 per cent more for 7 12 to 10 12 pitches and 30 per cent more for a pitch that is 11 12 or greater.

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. Near ridge of the roof. 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. Keep in mind you should always consult with a professional roofing company when determining how many air vents your roof should have.

The net free area nfa rating indicates the amount of space each roof vent covers. Also the nfa will be calculated differently if your roof slope is greater than average. Some local building codes carry special considerations that take precedence. 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.

You ll need the square footage of your attic to calculate the number of roof vents that you should need. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. You will need to have 1 square foot of vent area for every 150 square feet of attic space. Based on your 1100 sq.

Choosing round soffit vents for. For example if you have 1200 square feet of attic space you should need at least 4 air vents to ensure proper ventilation. 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. Always have a balanced ventilation system.