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.
Calculating attic ventalation.
So if your attic is 1 500 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.
Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.
The rule of thumb on the amount of vent space needed is approximately 1 sq.
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.
Here are the answers to the five most frequent questions pertaining to calculating attic ventilation.
Tips for assessing your needs.
Hence you would need two square feet 600 300 of attic ventilation.
Roof ventilation calculator enter your attic area or length and width to determine your ventilation needs.
Enter square footage calculate or enter the square footage of the attic or area to be vented.
Typically building codes include minimum requirements applicable to attic ventilation.
Width or area.
The roofing industry also has practical guide lines for attic ventilation.
As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area.
To calculate nfa take the attic square footage 2 square inches of exhaust and square inches of intake nfa needed.
Most attic ventilation manufacturers list the longer formula on their websites and inside key product brochures.
Calculation q a.
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.
Code requirements the international building code.
Of vent space for every 150 sq.
Ft you divide that by 150 to get 10 sq.
But the shortcut is just as good and faster.
To use this calculator first find the total square footage of the attic floor area.
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.
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.
