Attic Venting Requirements

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.

Attic venting requirements.

Code requirements the international building code 2012 edition ibc 2012 requires enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof framing to have cross ventilation for each separate space. Measure the length and width of the attic floor space to be ventilated. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Attic ventilation serves two main functions.

Calculate or enter the square footage of the attic or area to be vented. The net free vent area nfva shall not be less than 1 150 of the area of the space being vented. The ideal roof attic ventilation would consists of combination of vents located in upper section of the attic ridge vents turbine box shaped or dome static vents electric motor powered vents vents installed along the bottom parts of the roof overhang called intake or soffit vents hip vents and or gable vents all of the provided links are just samples vents manufactured by one company. Hence you would need two square feet 600 300 of attic ventilation.

As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area. I was told there would be no math. 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. You can also contact your local municipality to check on building code in your area.

Vents are rated by their net free area or the amount of space for air to flow in or out. What does the code require. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. You can calculate attic ventilation requirements by determining the square footage of your attic floor its width times its length and compare that to the total required net free area nfa.

And since just about all attics are vented the pressurized attic air is then naturally pushed outside through those vents. Attic venting requirements your airscape needs to breathe a whole house fan is designed to move air from your house into your attic. Of vent for every 300 sq. Enter your square footage.

Lines for attic ventilation.