Calculating Attic Ventilation Needs

Result of item 2 x 144.

Calculating attic ventilation needs. Building codes vary. Of vent for every 300 sq. Calculate or enter the square footage of the attic or area to be vented. Multiply the length of the attic times the width in feet to find the attic area then divide by 150 to find.

Ventilation manufacturers assign an nfa value to the non motorized vents they make. In order to find the right calculator divide the attic floor space by 300 sq feet. The home ventilating institute hvi recommends that powered attic ventilators provide at least 10 air changes per hour to equalize attic temperature. Determine the amount of ventilation needed for your home with this formula.

Divide the square inches by 2. Change the square feet to square inches. Measure the length and width of the attic floor space to be ventilated. For pitched roofs with vapor barriers.

Nfa is the unobstructed area through which air can pass through a vent usually measured in square inches. If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. Calculating attic ventilation requirements. Result of item 1 300.

Attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed. No vapor barrier and for some municipalities in hot climates. 1 cubic foot is 12 x 12 144 cubic inches. Calculate the total vent area needed.

Calculate the square footage of your attic and provide proper attic ventilation with the right number of roof vents ridge vents or soffit vents. Enter your square footage. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Next multiply the 4 square feet into cubic inches.

Calculate the square footage of the attic space. 1 square foot of ventilation for every 150 square feet of space. Calculate the area of your attic and the proper number of vents. 1 square foot of ventilation for every 300 square feet of space.

How to calculate attic vent area needed when adding soffit vents. Divide the total vent area by two to. Divide the square footage item 1 by 300.