How Many Attic Vents Do I Need

The downside of attic ventilation fans.

How many attic vents do i need.

To determine the total vent area measure the length and width of your attic in feet then multiply the two measurements to get the attic area then divide the number by 150 to get the vent space in square feet length x width 150. For a home with 2000 square feet of attic floor space you ll first divide 2000 by 300 2000 300 6 66. Since you want a balanced system you divide by 2 so that half of the ventilation is intake and half is exhaust. Attic ventilation fans whether hard wired or powered by their own solar panels seem like a low cost and effective way to help keep your house cool.

As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. How many vents will my house need. You need 6 66 square feet of attic ventilation. Based on your 1100 sq.

Building codes typically echo the administration s guidelines. Of vent for every 300 sq. Near ridge of the roof. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet.

The general rule is that you must have one square foot of vent space for every 150 square feet of attic area. If your attic floor has a vapor barrier you will need one square foot of nfa per every 300 square feet of attic floor area half of that will be intake half for exhaust. In no case should the amount of exhaust ventilation exceed the amount of intake 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.

This helps make it easy to calculate how many vents you need for your attic once you ve determined your requirements. Always have a balanced ventilation system. And this guideline you ll need a minimum of. The federal housing administration recommends 1 square foot of attic ventilation for every 150 square feet of attic space.

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.