Attic Ventilation Net Free Area

When installed as part of a properly balanced when installed as part of a properly balanced attic ventilation.

Attic ventilation net free area. Remember the minimum area requirement when using a continuous system is a ratio of 1 300. Kudos to michael blasnik and team for showing how this is done. This should be an adequate amount of passive intake ventilation to support your attic breeze fan. In 47 1 0 0 85 0 6316 1 34 1 1 5 1 10 0 4 10 5 2 100 0 25 100 49 14.

Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator. You can always measure the net free area of an existing attic using add a hole zone pressure blower door techniques. The ratio can be reduced to 1 300 if. We also find that if built to code at 2400 sqft of attic space your attic should already provide 8 0 sqft net free area of passive ventilation.

Your local weatherization agency should be able to fill you in on how those measurements are made. Get free shipping on qualified roofing attic ventilation or buy online pick up in store today in the building materials. See how simple that was. The net free area is always less than the actual area.

Ok so now we know the square footage of the attic area to be ventilated. Log in or create an account to post an answer. Nfa is the unobstructed area through which air can pass through a vent usually measured in square inches. Ventilation manufacturers assign an nfa value to the non motorized vents they make.

Of net free area of intake needed at or near the soffit. There is a vapor barrier installed in the attic over the living space or. This means that for each 150 square feet of attic floor space 1 square foot of net free area is required for ventilation. Eave vent gable vent roof jack.

The minimum net free ventilation area shall be 1 300 of the vented space if at least 40 percent and not more than 50 percent of the required ventilating area is provided by ventilators located in the upper portion of the attic or rafter space. Screen factor sf adjusts for airflow obstructed by screens and louvers. Now let s figure out how much ventilation space we need. Net free area nfa net venting area adjusting for insect screen louvers and weather coverings.

Calculate or enter the square footage of the attic or area to be vented. Attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed. 1 500 square feet 300 5 square feet.