Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.
Estimating ventilation requirements for attic.
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.
Typically building codes include minimum requirements applicable to attic ventilation.
Calculate the square footage of the attic space.
The open area of a vent is sometimes listed on the roof air vent as nfva net free vent area.
Hence you would need two square feet 600 300 of attic ventilation.
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.
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.
Code requirements the international building code.
It is important that air movement occurs and is not impeded by any framing members of the.
Generally as the roof pitch increases the volume inside the attic also increases along with the amount of needed.
Enter square footage calculate or enter the square footage of the attic or area to be vented.
If not measure the size yourself.
The building code lets you reduce that by half under some conditions but more roof ventilation is usually better.
The ridge vent is installed on the peak with nails and shingled over for aesthetic purposes.
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.
The two square feet is divided equally between the intake and the exhaust one square foot for each.
Calculating attic ventilation requirements.
Other options to meet your attic ventilation needs are.
Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.
Result of item 1 300.
In of vent opening per 150 sq.
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.
Foot of ventilation for every 150 sq.
Intake vents located at the lowest part of the roof under the eaves allow cool.
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.
Then aim for about 1 sq.
The roofing industry also has practical guide lines for attic ventilation.
