Attic Vents Per Square Foot

This helps make it easy to calculate how many vents you need for your attic once you ve determined your requirements.

Attic vents per square foot.

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. 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. The federal housing administration recommends 1 square foot of attic ventilation for every 150 square feet of attic space. Standard ridge vent produces 18 square inches of ventilating area per lineal foot.

Ben ericksonaugust 30 2007 at 3 09 pm. Of vent space for every 150 sq. If your attic floor has a vapor barrier you will need one square foot of nfa per every 300 square feet of attic floor area half of that will be intake half for exhaust. 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. Near ridge of the roof. So if your attic is 1 500 sq. Our roof is 50 feet long so using a standard product we will get 900 square inches of ventilating space.

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. So the ridge ventilation has exceeded the minimum requirement. 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. And this guideline you ll need a minimum of.

Nine hundred square inches equals 6 25 square feet. Based on your 1100 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. Building codes typically echo the administration s guidelines.