Dry air to enter the attic.
Open aur needed fir attic exhaust.
Ravc member companies have an extensive offering of intake and exhaust vents.
Always have a balanced ventilation system.
Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.
Attic square footage 4 square inches of exhaust and square inches of intake net free area needed.
Intake vents located at the lowest part of the roof under.
In no case should the amount of exhaust ventilation exceed the amount of intake ventilation.
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.
Cool air in hot air out attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.
Most building codes require a ratio of 1 150 ventilation space to attic floor space.
You can also contact your local municipality to check on building code in your area.
This allows cool dry air to enter the attic at the lowest point helping to remove any warm moist air from inside the attic through the exhaust vents along the entire underside of the roof deck.
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.
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.
Say the contractor is standing in front of a house that has an attic with 2 200 square feet.
Select your preferred type of exhaust system.
2 200 2 1 100 square inches of exhaust net free area needed.
The uniform building code requires that the amount of venting area in the attic be equal to 1 150 of the area of the floor and in most circumstances it allows a ratio of 1.
The following product options will allow you to achieve an exhaust nfva of 528 square inches.