Attic Ventilation Requirements

Roof insulation thermal resistance at roof perimeter should be equal or greater to thermal resistance of exterior wall.

Attic ventilation requirements.

Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. Typically building codes include minimum requirements applicable to attic ventilation. The recommended ventilation ratio to provide for vented attic assemblies when an air barrier is present is the 1 300 ratio as specified by most building codes. Divide the square footage item 1 by 300.

The majority of the requirements related to attic ventilation have not changed much from the previous editions. Hence you would need two square feet 600 300 of attic ventilation. 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.

This means that if you have a 1500 sq attic then you would need at least 10 sf of ventilation. Calculate the square footage of the attic space. Current regulations state that the minimum attic ventilation requirements are 150 1. 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. 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. Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.

The roofing industry also has practical guide lines for attic ventilation. The following are the requirements taken directly from the irc. Code requirements the international building code. Foot of ventilation for every 150 sq.

Attic ventilation is an important part of keeping your building healthy. The two square feet is divided equally between the intake and the exhaust one square foot for each. 1 300 ventilation ratio recommended. Result of item 1 300.

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. Intake vents located at the lowest part of the roof under the eaves allow cool.