Minimum Attic Ventilation Requirements

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

Minimum attic ventilation requirements. Attic ventilation is an important part of keeping your building healthy. The majority of the requirements related to attic ventilation have not changed much from the previous editions. The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

Based on your 1100 sq. The roofing industry also has practical guide lines for attic ventilation. In order to have a balanced ventilation system you need to have the right roof vent calculation. Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.

Exhaust nfva near ridge of the roof. The federal housing authority fha and the urban development hud have established minimum requirements for attic ventilation. And this guideline you ll need a minimum of. Of net free area of intake needed at or near the soffit.

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. According to the fha federal housing administration us for every 300 square feet of attic floor area you should have at minimum one square foot ventilation. Figure 1 soffit to ridge attic ventilation. 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.

Current regulations state that the minimum attic ventilation requirements are 150 1. For the 1 150 attic ventilation requirement simply double the amount of exhaust and intake calculated. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space. The following are the requirements taken directly from the irc.

Of net free area of exhaust needed at or near the ridge. Ridge static attic vents 384 00 minimum sq. At least code required minimum ventilation b balance ventilation between intake and exhaust c control heat moisture and air fl ow between the attic and the occupied space this document outlines reasons for ventilating roofs provides design guidelines discusses regulatory requirements and identifi es roof ventilation. 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.

As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area.