Attic Vents Per Square Foot

Ben ericksonaugust 30 2007 at 3 09 pm.

Attic vents per square foot.

Milt the rule of thumb on the amount of vent space needed is approximately 1 sq. 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. So the ridge ventilation has exceeded the minimum requirement. This shortcut conveniently calculates the 2015 international residential building code minimum irc section r806 roof ventilation 1 which states in part 1 square foot of net free area for every 150 square feet of attic floor space with the attic defined as length x width floor of the attic.

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. Standard ridge vent produces 18 square inches of ventilating area per lineal foot. Based on your 1100 sq. And this guideline you ll need a minimum of.

Our roof is 50 feet long so using a standard product we will get 900 square inches of ventilating space. Ft you divide that by 150 to get 10 sq. The federal housing administration recommends 1 square foot of attic ventilation for every 150 square feet of attic space. 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.

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. Near ridge of the roof. Of vent space for every 150 sq. 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.

1 square foot of ventilation for every 300 square feet of space for pitched roofs with vapor barriers 1 square foot of ventilation for every 150 square feet of space no vapor barrier and for some municipalities in hot climates. So if your attic is 1 500 sq. 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. Nine hundred square inches equals 6 25 square feet.