Attic Venting Requirements

Mark the roof venting locations from the attic where you can see the rafters and avoid placing roofing vents over them.

Attic venting requirements.

Vents are rated by their net free area or the amount of space for air to flow in or out. You can calculate attic ventilation requirements by determining the square footage of your attic floor its width times its length and compare that to the total required net free area nfa. The following are the requirements taken directly from the irc. Calculating attic ventilation requirements.

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. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems. A ridge vent is a ventilation strip that is placed along the ridgeline of the home.

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. Feet of attic space divided 50 50. Adding attic vents is a simple matter of cutting holes and installing vents. The two square feet is divided equally between the intake and the exhaust one square foot for each.

Code requirements the international building code. Divide the square footage item 1 by 300. Result of item 1 300. 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.

Typically building codes include minimum requirements applicable to attic ventilation. Hence you would need two square feet 600 300 of attic ventilation. Foot of ventilation for every 150 sq. But before you cut any holes plan the locations of the attic vents.

Intake vents located at the lowest part of the roof under the eaves allow cool. The roofing industry also has practical guide lines for attic ventilation. The majority of the requirements related to attic ventilation have not changed much from the previous editions. 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.

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.