Attic Venting Requirements

Vents are rated by their net free area or the amount of space for air to flow in or out.

Attic venting requirements.

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. 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. Photos 1 6 show how it s done.

The two square feet is divided equally between the intake and the exhaust one square foot for each. 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. Calculating attic ventilation requirements. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction.

Code requirements the international building code. The roofing industry also has practical guide lines for attic ventilation. Foot of ventilation for every 150 sq. Intake vents located at the lowest part of the roof under the eaves allow cool.

Adding attic vents is a simple matter of cutting holes and installing vents. But before you cut any holes plan the locations of the attic vents. A ridge vent is a ventilation strip that is placed along the ridgeline of the home. Calculate the square footage of the attic space.

The following are the requirements taken directly from the irc. 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. Result of item 1 300. Mark the roof venting locations from the attic where you can see the rafters and avoid placing roofing vents over them.

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. Typically building codes include minimum requirements applicable to attic ventilation. Feet of attic space divided 50 50. 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.