Materials / Ridge Vent
Ridge Vent
accessoryA ridge vent is a continuous exhaust vent cut into the roof sheathing along the ridge line and covered by a rigid or shingle-over cap, letting warm, moist attic air escape as part of a balanced intake-and-exhaust system. IRC Section R806.2 sets the minimum net free ventilating area at 1/150 of the vented space, reducible to 1/300 where a Class I or II vapor retarder is installed (Climate Zones 6-8) and 40-50 percent of the ventilating area is provided by upper ventilators within 3 feet of the ridge. R806.1 requires ventilation openings to have a least dimension of 1/16 to 1/4 inch, or be covered with corrosion-resistant screening in that same range. Manufacturers publish each product's net free area (NFVA) in square inches per linear foot. Used on steep-slope roofs.
- provides continuous exhaust across the full ridge for even attic airflow
- low profile keeps the roofline visually clean compared to discrete vents
- net free area is published per linear foot, simplifying total-area calculations
- pairs with soffit or eave intake vents to form a balanced ventilation system
- requires a continuous ridge cut, adding labor versus discrete roof vents
- performs poorly on hip roofs or roofs with short ridge runs
- net free area varies by product, so specs must be checked per manufacturer
- improper baffle or insulation clearance at the ridge can block airflow
Sources
- seattle.gov verified 2026-07-28