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.
How many roof vents do i need for my house.
Hvi recommends a ratio of 60 to 40 for soffit ventilation to gable or ridge ventilation.
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.
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.
Use the calculator below to find out how many exhaust and intake vents you will need on your house.
Choosing round soffit vents for.
The downside of attic ventilation fans.
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.
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.
Thus if your attic is 450 square feet you need roof vents equaling 3 square feet.
These specialty vents do not affect the.
Without exception you should talk to a professional to determine what your home requires.
As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space.
In no case should the amount of exhaust ventilation exceed the amount of intake ventilation.
Rafter vents or insulation baffles install in any rafter space to create narrow gaps that direct fresh air from the soffit vents to the peak of the roof.
Always have a balanced ventilation system.
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.
Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator.
Generally speaking you need a ratio of 1 300 where for every 300 square feet of ceiling space you need 1 square foot of attic ventilation.
That said air resistance and interference such as vent grates reduces the area of true ventilation.
Choose one of the following products to meet the recommended exhaust nfva of 528 square inches.