How To Size An Attic Exhaust Fan

Use a tape measure to get an accurate measurement.

How to size an attic exhaust fan.

That translates to one attic vent 3 feet by 3 feet or two attic vents. You multiply length times width times height. To determine the size of your attic multiply the width by the length of the attic floor in feet. How to size attic exhaust vent fans for your home attic size.

Cfm cubic feet per minute is a measure of the amount of air the fan moves in a minute. Next multiply the square feet of attic space by 0 7 to get the minimum number of cubic feet of air per. Measure the distance between the studs on the left and right side of your vent. Attic fan size cfm 0 7 x sq ft area of the attic formula 1 the size of an attic fan is calculated in terms of cfm.

You now need to multiply 960 x 15. 10 feet x 12 feet x 8 feet that computes to 960 cubic feet of air in the room. When you re finished write the number down somewhere you ll need it to find the right size piece of plywood for your attic fan to be installed on. If you need 6 000 cfm of air flow through your house divide 6 000 by 750 to get a minimum 8 square feet of attic venting.

Some professionals multiply the square feet value with 0 6 instead of 0 7.