Attic Venting Requirements

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.

Attic venting requirements.

Vents are rated by their net free area or the amount of space for air to flow in or out. The two square feet is divided equally between the intake and the exhaust one square foot for each. 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.

The following are the requirements taken directly from the irc. Mark the roof venting locations from the attic where you can see the rafters and avoid placing roofing vents over them. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction. 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. Typically building codes include minimum requirements applicable to attic ventilation. The roofing industry also has practical guide lines for attic ventilation. Result of item 1 300.

Calculate the square footage of the attic space. A ridge vent is a ventilation strip that is placed along the ridgeline of the home. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. But before you cut any holes plan the locations of the attic vents.

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 majority of the requirements related to attic ventilation have not changed much from the previous editions. Foot of ventilation for every 150 sq. 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.

Calculating attic ventilation requirements. Intake vents located at the lowest part of the roof under the eaves allow cool. Divide the square footage item 1 by 300. Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.

Adding attic vents is a simple matter of cutting holes and installing vents.