Attic Venting Requirements

Lines for attic ventilation.

Attic venting requirements.

Vents are rated by their net free area or the amount of space for air to flow in or out. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. And since just about all attics are vented the pressurized attic air is then naturally pushed outside through those vents. Attic ventilation serves two main functions.

Measure the length and width of the attic floor space to be ventilated. 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. 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.

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. 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. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. The net free vent area nfva shall not be less than 1 150 of the area of the space being vented.

Of vent for every 300 sq. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Calculate or enter the square footage of the attic or area to be vented. Attic venting requirements your airscape needs to breathe a whole house fan is designed to move air from your house into your attic.

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. Enter your square footage. What does the code require. You can also contact your local municipality to check on building code in your area.

Balance is the key.