Attic Ventilation Requirements Calculator

Calculate the total vent area needed.

Attic ventilation requirements calculator.

Ventilation calculator 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. 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. Next multiply the 4 square feet into cubic inches. For balanced ventilation an equal amount of intake vent area net free area should also be installed.

If local code requires the 1 150 rule please double the requirements. All lomanco attic ventilation product requirements are based on the minimum standard 1 300 rule as set forth by the international building code ibc and the international residential code irc. 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. In order to find the right calculator divide the attic floor space by 300 sq feet.

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. Use avp s roof vent calculator to determine the number and size of exhaust vents you will need. As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area. Use the duraflo ventilation calculator to determine your home s ventilation requirements.

The calculator will determine the number of square inches of net free area required for adequate attic ventilation based on the 1 300th general requirement. Determine the square footage of the attic or area to be vented choose your square footage 500sq 600sq 700sq 800sq 900sq 1000sq 1100sq 1200sq 1300sq 1400sq 1500sq 1600sq 1700sq 1800sq 1900sq 2000sq 2100sq 2200sq 2300sq 2400sq 2500sq 2600sq 2700sq 2800sq 2900sq 3000sq. Here s how to determine your requirements. 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.

Hence you would need two square feet 600 300 of attic ventilation. Multiply the length of the attic times the width in feet to find the attic area then divide by 150 to find the total square feet of vent space needed. In our case the required 4 vents for the 1200 sq ft house multiply the 144 cubic inches by 4 576 cubic inches. Our soffit vents round back vents pop vents and universal vents make excellent intake vents.

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.