Roof Vent Free Area

The passive vent net free area table gives the net free area ventilation for some common roof and gable passive vents.

Roof vent free area.

So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements. Large 16 1 2 x 16 1 2 in. Venting products are normally rated with a net free area nfa. Universal dormer vent universal dormer vent 135 sq.

Net free area uv 135. Ideally the nfa of the soffits should be equal or greater than that of the ridge vent and in no case should the amount of exhaust ventilation exceed the amount of intake ventilation. This vent features an 1 8th inch internal aluminum screen to prevent intrusion by birds or large insects. Base offers added weatherproofing protection and ease of installation.

The calculations before indicated that we needed 2 square feet of ridge or upper roof ventilation. Ventsure 4 foot strip heat moisture ridge vent with weather protector moisture barrier. Calculate or enter the square footage of the attic or area to be vented. Balanced ventilation will prolong the life of your roof while providing energy savings and comfort.

The nfa is the open area that exists for air to pass through. Made in the usa. The key to effective venting is to balance air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge. Active ventilation products inc.

Sheet metal manufacturers of roof vents roof exhaust fans and solar attic fans. Two square feet equals 288 square inches. Build your roof empowers you to select each layer and component that goes into your total protection roofing system so that you get the roof you want to protect your home.