Tips for assessing your needs.
Calculating attic ventalation.
To use this calculator first find the total square footage of the attic floor area.
As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area.
The roofing industry also has practical guide lines for attic ventilation.
Code requirements the international building code.
Calculation q a.
Roof mount power fans are a type of motor driven attic exhaust vent that make up half of a balanced attic ventilation system for each roof.
Hence you would need two square feet 600 300 of attic ventilation.
Here are the answers to the five most frequent questions pertaining to calculating attic ventilation.
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.
Ft you divide that by 150 to get 10 sq.
To calculate nfa take the attic square footage 2 square inches of exhaust and square inches of intake nfa needed.
Width or area.
Most attic ventilation manufacturers list the longer formula on their websites and inside key product brochures.
But the shortcut is just as good and faster.
Enter square footage calculate or enter the square footage of the attic or area to be vented.
Select ventilation product flex roll ridge vent multi roll multi purpose vent rigid roll ridge.
Round your calculations up to the next highest number see ventilations requirements.
Roof ventilation calculator enter your attic area or length and width to determine your ventilation needs.
Typically building codes include minimum requirements applicable to attic ventilation.
According to the fha federal housing administration us for every 300 square feet of attic floor area you should have at minimum one square foot ventilation.
Of vent space for every 150 sq.
This calculates the 2015 international residential building code minimum irc section r806 roof ventilation 1 which states that 1 square foot of net free area for every 150 square feet of attic floor space with the attic.
Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator.
So if your attic is 1 500 sq.
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 can be an impor tant performance consideration when design ing and installing steep slope roof systems.
