Calculating Attic Ventilation Needs

In order to find the right calculator divide the attic floor space by 300 sq feet.

Calculating attic ventilation needs.

If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. Multiply the length of the attic times the width in feet to find the attic area then divide by 150 to find. Attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq.

The home ventilating institute hvi recommends that powered attic ventilators provide at least 10 air changes per hour to equalize attic temperature. No vapor barrier and for some municipalities in hot climates. Calculate the square footage of your attic and provide proper attic ventilation with the right number of roof vents ridge vents or soffit vents. Measure the length and width of the attic floor space to be ventilated.

1 square foot of ventilation for every 300 square feet of space. Next multiply the 4 square feet into cubic inches. Change the square feet to square inches. Building codes vary.

Nfa is the unobstructed area through which air can pass through a vent usually measured in square inches. Calculate the total vent area needed. Determine the amount of ventilation needed for your home with this formula. Calculating attic ventilation requirements.

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

Calculate the soffit vent area needed. Result of item 2 x 144. Result of item 3 2. Divide the square inches by 2.

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. Divide the square footage item 1 by 300. For pitched roofs with vapor barriers. Calculate or enter the square footage of the attic or area to be vented.

Result of item 1 300. Divide the total vent area by two to. 1 cubic foot is 12 x 12 144 cubic inches.