Attic Ventilation Requirements

Code requirements the international building code.

Attic ventilation requirements.

The majority of the requirements related to attic ventilation have not changed much from the previous editions. Current regulations state that the minimum attic ventilation requirements are 150 1. The roofing industry also has practical guide lines for attic ventilation. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

Divide the square footage item 1 by 300. 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. 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 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.

Intake vents located at the lowest part of the roof under the eaves allow cool. 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. Foot of ventilation for every 150 sq. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction.

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

Result of item 1 300. Hence you would need two square feet 600 300 of attic ventilation. This means that if you have a 1500 sq attic then you would need at least 10 sf of ventilation. 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.

The following are the requirements taken directly from the irc. 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. Feet of attic space divided 50 50.

Typically building codes include minimum requirements applicable to attic ventilation. Calculating attic ventilation requirements.