Attic Fan Ventilation Requirements

Calculate or enter the square footage of the attic or area to be vented.

Attic fan ventilation requirements.

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. Enter your square footage. 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. Complete coverage of the attic floor along with sealing air leaks will ensure you get the best performance from your insulation.

Bountiful eave soffit ventilation space. Building codes vary. 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. 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. Attic fans perform this ventilation by pushing hot air out into the environment while also pulling fresh cool air into the attic. 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. Tips for assessing your needs.

An attic floor that is thoroughly air sealed. Attic insulation that is less than r 19. Hvac equipment in the attic that is well insulated and sealed. Most building codes require a ratio of 1 150 ventilation space to attic floor space.

In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. You can also contact your local municipality to check on building code in your area. Attic x 0 7 700 cfm minimum fan rating add an additional 20 cfm x 1 20 if you have a steep roof and 15 cfm x 1 15 for a dark roof. 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.

The result is a cooler attic space with plenty of air exchange.