Attic Fan Ventilation Requirements

Vents are rated by their net free area or the amount of space for air to flow in or out.

Attic fan ventilation requirements. Building codes vary. Attic fans perform this ventilation by pushing hot air out into the environment while also pulling fresh cool air into the attic. Bountiful eave soffit ventilation space. Attic insulation that is less than r 19.

Calculate or enter the square footage of the attic or area to be vented. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Of vent for every 300 sq. 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 result is a cooler attic space with plenty of air exchange. 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. Tips for assessing your needs. 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.

Ventilation openings having a least dimension larger than 1 4 inch 6 4 mm shall be provided with corrosion resistant wire cloth screening hardware cloth perforated vinyl or similar material with openings having a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum. An attic floor that is thoroughly air sealed. Rafter vents ensure the soffit vents are clear and there is a channel for outside air to move into the attic at the soffits and out through the gable or ridge vent. Enter your square footage.

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. Attic vent fans are commonly rated from 800 to 1 600 cfm making one fans suitable for attics of up to around 2 200 square feet. Hvac equipment in the attic that is well insulated and sealed. Complete coverage of the attic floor along with sealing air leaks will ensure you get the best performance from your insulation.

You can also contact your local municipality to check on building code in your area.