How Much Roof Vents Do I Need

Thus if your attic is 450 square feet you need roof vents equaling 3 square feet.

How much roof vents do i need. Building codes vary. How many vents will my house need. 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. If the slope of your roof is greater than 6 12 you will need more ventilation to reflect the extra volume of attic space.

Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge. Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge. Of vent for every 300 sq. Asphalt roofing and nrca.

As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. That said air resistance and interference such as vent grates reduces the area of true ventilation. 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. Based on your 1100 sq.

In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. And this guideline you ll need a minimum of. Because you always want your intake nfa to meet or exceed the amount of exhaust nfa we will take the amount of exhaust provided and divide by the nfa rating of the deck air. 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.

Near ridge of the roof. 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 other words the entire vent opening doesn t count as vented space. Rounding up you would need ten 10 750 vents.

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.