Calculating Attic Ventilation Needs

Measure the length and width of the attic floor space to be ventilated.

Calculating attic ventilation needs.

1 square foot of ventilation for every 300 square feet of space. Calculate the soffit vent area needed. Change the square feet to square inches. Next multiply the 4 square feet into cubic inches.

How to calculate attic vent area needed when adding soffit vents. Building codes vary. Calculate or enter the square footage of the attic or area to be vented. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq.

Nfa is the unobstructed area through which air can pass through a vent usually measured in square inches. The home ventilating institute hvi recommends that powered attic ventilators provide at least 10 air changes per hour to equalize attic temperature. Divide the total vent area by two to. If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation.

Attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed. In order to find the right calculator divide the attic floor space by 300 sq feet. No vapor barrier and for some municipalities in hot climates. Of vent for every 300 sq.

Calculate the square footage of your attic and provide proper attic ventilation with the right number of roof vents ridge vents or soffit vents. 1 square foot of ventilation for every 150 square feet of space. Determine the amount of ventilation needed for your home with this formula. Calculate the square footage of the attic space.

1 cubic foot is 12 x 12 144 cubic inches. For pitched roofs with vapor barriers. Enter your square footage. Result of item 1 300.

Result of item 3 2. Calculate the area of your attic and the proper number of vents. Calculating attic ventilation requirements. Divide the square inches by 2.

Multiply the length of the attic times the width in feet to find the attic area then divide by 150 to find. Result of item 2 x 144. Attic ventilation calculator effective attic ventilation requires air to exit at or near the peak of the roof and replacement air to be drawn in under the eaves of the house via soffit venting.