Attic Venting Requirements

Calculating attic ventilation requirements.

Attic venting requirements.

Hence you would need two square feet 600 300 of attic ventilation. Foot of ventilation for every 150 sq. Divide the square footage item 1 by 300. Feet of attic space divided 50 50.

Vents are rated by their net free area or the amount of space for air to flow in or out. Code requirements the international building code. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. 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.

But before you cut any holes plan the locations of the attic vents. Mark the roof venting locations from the attic where you can see the rafters and avoid placing roofing vents over them. Typically building codes include minimum requirements applicable to attic ventilation. 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. 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. 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.

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

The following are the requirements taken directly from the irc. The roofing industry also has practical guide lines for attic ventilation. Calculate the square footage of the attic space. The two square feet is divided equally between the intake and the exhaust one square foot for each.

Photos 1 6 show how it s done.