Attic Venting Requirements

Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

Attic venting requirements.

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. Result of item 1 300. The majority of the requirements related to attic ventilation have not changed much from the previous editions. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction.

Photos 1 6 show how it s done. 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. But before you cut any holes plan the locations of the attic vents. Calculate the square footage of the attic space.

Intake vents located at the lowest part of the roof under the eaves allow cool. A ridge vent is a ventilation strip that is placed along the ridgeline of the home. Mark the roof venting locations from the attic where you can see the rafters and avoid placing roofing vents over them. 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.

Hence you would need two square feet 600 300 of attic ventilation. Code requirements the international building code. Typically building codes include minimum requirements applicable to attic ventilation. Calculating attic ventilation requirements.

Foot of ventilation for every 150 sq. The two square feet is divided equally between the intake and the exhaust one square foot for each. 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. Divide the square footage item 1 by 300.

Vents are rated by their net free area or the amount of space for air to flow in or out. Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems. Feet of attic space divided 50 50. 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.

The following are the requirements taken directly from the irc.