Attic Space Venting Requirements

Attics must have a minimum of 1 square foot of ventilation openings for every 150 square feet of floor space.

Attic space venting requirements.

Code requirements the international building code. Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space. Typically building codes include minimum requirements applicable to attic ventilation.

Choose one of the following products to meet the recommended intake nfva of 528 square inches. The two square feet is divided equally between the intake and the exhaust one square foot for each. The roofing industry also has practical guide lines for attic ventilation. 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.

It really is a design choice. Calculate the square footage of the attic space. Divide the square footage item 1 by 300. There should also be a 50 50 balance of attic venting and roof venting.

Hence you would need two square feet 600 300 of attic ventilation. The following is a list of options for installing ventilation into a residential attic space. Calculate net free vent space. Requirements for unvented attics can be found in section r806 5 of the 2018 irc.

The following product options will allow you to achieve an intake nfva of 528 square inches. 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. If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

So the decision to vent an attic space is not dictated by building code. The venting space should be equally divided between intake. Allows cool dry air to enter the attic. In order to find the right calculator divide the attic floor.

Intake vents located at the lowest part of the roof under the eaves allow cool. Calculating attic ventilation requirements. Result of item 1 300. 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.

Building codes typically require 1 square foot of venting space for every 150 square feet of attic space.