How Many Roof Vents Do I Need?

A roof vent is a fixture installed at various points on your roof and in your attic that provides either intake or outflow of moving air. The size of your roof and attic space will determine how many roof vents you need, and there is a basic formula you can use to determine this. Read on to learn which kinds of vents will work best for your roof and how many you need to install.

Roof Vent Types

Ridge vents run along the apex of your roof and are long and narrow. Gable vents attach the gables and go through the siding. Under-eave or soffit vents are installed on the underside of the roof that hangs over the siding–the eaves. There are box- or dome-shaped vents that go through the roof itself. Vents can be manual or electric powered to increase air circulation.

How Many Your Roof Needs

As a general rule, your roof needs 1 square foot of vent area for every 150 square feet of attic space. Thus, if you attic is 450 square feet, you will need roof vents equaling 3 square feet. They should be divided equally between inlet and outlet vents and can be in any combination that will work with your roof design.

Calculate how many roof vents your home needs by following the ratio 1 sq. ft. to every 150 sq. ft. of attic space. Split them equally between intake and outflow vents for the best air circulation.