Most attic ventilation manufacturers list the longer formula on their websites and inside key product brochures.
Calculating attic ventalation.
Round your calculations up to the next highest number see ventilations requirements.
But the shortcut is just as good and faster.
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.
Code requirements the international building code.
As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area.
Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.
Here are the answers to the five most frequent questions pertaining to calculating attic ventilation.
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.
Ridge vent intake vent calculator for standard gable attic.
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.
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.
Enter square footage calculate or enter the square footage of the attic or area to be vented.
The roofing industry also has practical guide lines for attic ventilation.
To calculate nfa take the attic square footage 2 square inches of exhaust and square inches of intake nfa needed.
Typically building codes include minimum requirements applicable to attic ventilation.
Tips for assessing your needs.
Hence you would need two square feet 600 300 of attic ventilation.
The rule of thumb on the amount of vent space needed is approximately 1 sq.
Select ventilation product flex roll ridge vent multi roll multi purpose vent rigid roll ridge.
Then look across to the number under the minimum length of ridge column.
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.
Calculation q a.
So if your attic is 1 500 sq.
Of vent space for every 150 sq.
To use this calculator first find the total square footage of the attic floor area.
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.
