Roof Attic Ventilation Requirement

Code requirements the international building code.

Roof attic ventilation requirement.

The following are the requirements taken directly from the irc. Feet of attic space divided 50 50. The majority of the requirements related to attic ventilation have not changed much from the previous editions. Throughout the balance of this digest the terms attic and roof will and can be used interchangeably.

Foot of ventilation for every 150 sq. Effective attic ventilation systems reduce damaging heat and moisture in your attic promote energy efficiency by helping to reduce the load on your air conditioner in the summer and also reduce the risk of ice dam formation on your roof. The amount of space you devote to intake must be equal to the amount you allow for exhaust and these must be calculated according to the size of your attic and slope of your roof. You can calculate attic ventilation requirements by determining the square footage of your attic.

Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems. 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. Most building codes require a ratio of 1 150 ventilation space to attic floor space.

In cold climates the primary purpose of attic or roof ventilation is to maintain a cold roof temperature to control ice dams created by melting snow and to vent moisture that moves from the conditioned space to the attic ventilation acts to bypass the vapour barrier created by most roof. 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. See the benefits of attic ventilation a new roof is more than just shingles. 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.

You can also contact your local municipality to check on building code in your area. 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. Explore owens corning ventilation products.

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