How Many Roof Vents Do I Need For My House

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.

How many roof vents do i need for my house. 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. 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. Always have a balanced ventilation system. If there is no vapor barrier double it to one square foot of nfa for every 150 square feet of attic floor space half for intake half for exhaust.

In no case should the amount of exhaust ventilation exceed the amount of intake ventilation. 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. Use the calculator below to find out how many exhaust and intake vents you will need on your house. 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.

The downside of attic ventilation fans. Without exception you should talk to a professional to determine what your home requires. Choose one of the following products to meet the recommended exhaust nfva of 528 square inches. 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.

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. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. Ideally there should also be plenty of soffit intake space their calculations recommend 336 net square inches of open soffit ventilation to supply 700 cfm. Choosing round soffit vents for.

These specialty vents do not affect the. 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. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. 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.