Materials / Box and Turtle Vents

A box or turtle vent is an individual static roof louver installed near the ridge to exhaust attic heat and moisture without moving parts. IRC Section R806 governs attic ventilation: R806.1 requires enclosed attics to have cross ventilation through openings protected against rain and snow entry, and R806.2 sets the minimum net free ventilating area at 1/150 of the vented space, reducible to 1/300 when a Class I or II vapor retarder is installed and 40-50 percent of the ventilating area sits in the upper attic near the ridge. Manufacturers rate individual louvers by net free area in square inches; multiple units combine with soffit intake to meet the required total on steep-slope roofs.