Attic ventilation requirements how many attic vents your roof needs industry standard for proper attic ventilation recommends for no vapor retarder type of attic insulation no paper plastic or aluminum layer between the attic floor and insulation layer 1 sq.
Estimating ventilation requirements for attic.
Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.
Standard attic vents like af 50 s ventilation fans or solar powered attic fans.
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.
Ridge vents are one of the easiest ways to meet roof venting requirements.
It is important that air movement occurs and is not impeded by any framing members of the.
A ridge vent is a ventilation strip that is placed along the ridgeline of the home.
Intake vents located at the lowest part of the roof under the eaves allow cool.
Code requirements the international building code.
If not measure the size yourself.
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.
Feet of attic space divided 50 50.
Hence you would need two square feet 600 300 of attic ventilation.
The open area of a vent is sometimes listed on the roof air vent as nfva net free vent area.
The ridge vent is installed on the peak with nails and shingled over for aesthetic purposes.
Other options to meet your attic ventilation needs are.
The two square feet is divided equally between the intake and the exhaust one square foot for each.
Typically building codes include minimum requirements applicable to attic ventilation.
Then aim for about 1 sq.
Foot of ventilation for every 150 sq.
Enter square footage calculate or enter the square footage of the attic or area to be vented.
The roofing industry also has practical guide lines for attic ventilation.
How does roof pitch come into play when calculating attic ventilation current irc requirements do not factor the role a roof s pitch plays in the amount of attic ventilation needed but ventilation manufacturers do.
Divide the square footage item 1 by 300.
In of vent opening per 150 sq.
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.
The building code lets you reduce that by half under some conditions but more roof ventilation is usually better.
Prior to installing the ridge vent a 1 inch wide strip of roof decking is cut out along both sides of the ridgeline to allow for air movement through the vent.
Generally as the roof pitch increases the volume inside the attic also increases along with the amount of needed.
Calculate the square footage of the attic space.
