Calculating Attic Ventalation

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.

Calculating attic ventalation. 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. So if your attic is 1 500 sq. Width or area.

Ft you divide that by 150 to get 10 sq. As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area. Typically building codes include minimum requirements applicable to attic ventilation. Hence you would need two square feet 600 300 of attic ventilation.

Ridge vent intake vent calculator for standard gable attic. Tips for assessing your needs. To calculate nfa take the attic square footage 2 square inches of exhaust and square inches of intake nfa needed. 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.

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. Enter square footage calculate or enter the square footage of the attic or area to be vented. 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. Most attic ventilation manufacturers list the longer formula on their websites and inside key product brochures.

To use this calculator first find the total square footage of the attic floor area. But the shortcut is just as good and faster. Calculation q a. Then look across to the number under the minimum length of ridge column.

Code requirements the international building code. 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. Select ventilation product flex roll ridge vent multi roll multi purpose vent rigid roll ridge.

Roof ventilation calculator enter your attic area or length and width to determine your ventilation needs. The roofing industry also has practical guide lines for attic ventilation.