Calculating Attic Ventilation Needs

Nfa is the unobstructed area through which air can pass through a vent usually measured in square inches.

Calculating attic ventilation needs.

Result of item 1 300. Calculate or enter the square footage of the attic or area to be vented. 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. Of vent for every 300 sq.

Divide the total vent area by two to. Calculate the square footage of the attic space. Calculate the soffit vent area needed. The home ventilating institute hvi recommends that powered attic ventilators provide at least 10 air changes per hour to equalize attic temperature.

In order to find the right calculator divide the attic floor space by 300 sq feet. Divide the square footage item 1 by 300. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Change the square feet to square inches.

If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. Determine the amount of ventilation needed for your home with this formula. 1 cubic foot is 12 x 12 144 cubic inches. Result of item 2 x 144.

No vapor barrier and for some municipalities in hot climates. For pitched roofs with vapor barriers. Building codes vary. Attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed.

1 square foot of ventilation for every 150 square feet of space. How to calculate attic vent area needed when adding soffit vents. Calculate the total vent area needed. 1 square foot of ventilation for every 300 square feet of space.

Measure the length and width of the attic floor space to be ventilated. Divide the square inches by 2. Calculate the square footage of your attic and provide proper attic ventilation with the right number of roof vents ridge vents or soffit vents. Result of item 3 2.

Calculating attic ventilation requirements. Multiply the length of the attic times the width in feet to find the attic area then divide by 150 to find. Next multiply the 4 square feet into cubic inches.