Calculating Attic Ventilation Needs

Divide the total vent area by two to.

Calculating attic ventilation needs.

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. Measure the length and width of the attic floor space to be ventilated. Calculate the area of your attic and the proper number of vents. Nfa is the unobstructed area through which air can pass through a vent usually measured in square inches.

Next multiply the 4 square feet into cubic inches. For pitched roofs with vapor barriers. 1 square foot of ventilation for every 300 square feet of space. Change the square feet to square inches.

How to calculate attic vent area needed when adding soffit vents. Calculate the soffit vent area needed. In order to find the right calculator divide the attic floor space by 300 sq feet. Calculate the square footage of the attic space.

Calculating attic ventilation requirements. Result of item 2 x 144. Calculate the total vent area needed. Building codes vary.

The home ventilating institute hvi recommends that powered attic ventilators provide at least 10 air changes per hour to equalize attic temperature. 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. 1 square foot of ventilation for every 150 square feet of space.

Divide the square inches by 2. No vapor barrier and for some municipalities in hot climates. Result of item 3 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.

If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq. Divide the square footage item 1 by 300. Determine the amount of ventilation needed for your home with this formula.

Of vent for every 300 sq. Enter your square footage. 1 cubic foot is 12 x 12 144 cubic inches.