Calculating Minimum Attic Ventilation

According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space.

Calculating minimum attic ventilation.

Divide the square footage item 1 by 300. Enter square footage calculate or enter the square footage of the attic or area to be vented. Calculate the total vent area needed. 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.

For balanced ventilation an equal amount of intake vent area net free area should also be installed. Let s use the following simple ranch house for an example. The federal housing authority fha and the urban development hud have established minimum requirements for attic ventilation. Length x width of attic in feet 150 total sq.

Calculating ventilation area of attic kitchen ventilation text. Divide the square inches by 2. Result of item 3 2. The house measures 30 feet by 50 feet.

Result of item 1 300. Change the square feet to square inches. Ft divided by 150 equals 10 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.

The result of item 4 is the minimum of square inch. This means that if you have a 1500 sq attic then you would need at least 10 sf of ventilation. Use avp s roof vent calculator to determine the number and size of exhaust vents you will need. 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.

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. Of total vent space needed. A 50 x 30 attic would have a total area of 1 500 sq. Attic ventilation is an important part of keeping your building healthy.

Calculate the square footage of the attic space. Result of item 2 x 144. Ok to determine how much ventilation area you need for your house all you need to know is the square foot area of the attic to be ventilated. 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. A discussion on attic ventilation isn t complete without going over the calculations to determine the minimum required net free ventilating area nfva. Current regulations state that the minimum attic ventilation requirements are 150 1.