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Net Free Area

Net Free Area is a standard measurement of a vent which describes the amount of space available through which air can flow. The chart below specifies that Net Fee Area, commonly abbreviated NFA, for our PV and AV vents based on the diameter of the vent. It is this area which is used to calculate the amount of ventilation a given number of vents will allow. Our Ventilation Calculator is a useful tool to find the number of exhaust vents needed for a given attic area. Keep in mind that intake and exhaust vents need to be balanced to effectively ventilate any space. If you have further questions, do not hesitate to call our office (during business hours) at 1-800-Roofvent or email us at sales@roofvents.com