Attic Vents Per Square Foot

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.

Attic vents per square foot.

Near ridge of the roof. Building codes typically echo the administration s guidelines. So if your attic is 1 500 sq. The federal housing administration recommends 1 square foot of attic ventilation for every 150 square feet of attic space.

Our roof is 50 feet long so using a standard product we will get 900 square inches of ventilating space. 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. 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. Standard ridge vent produces 18 square inches of ventilating area per lineal foot.

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. Based on your 1100 sq. 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.

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. 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. This helps make it easy to calculate how many vents you need for your attic once you ve determined your requirements. Ft you divide that by 150 to get 10 sq.

So the ridge ventilation has exceeded the minimum requirement. Ben ericksonaugust 30 2007 at 3 09 pm. 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.