How far from the edge of the roof should a ridge vent stop?
Why stop short of the edge
The last few inches of a ridge sit over the gable end wall, where there is little or no attic space to vent and where wind hits hardest. An open slot there invites wind-driven rain to blow straight in. Leaving solid decking at the ends also keeps the rake edge and the last cap shingles fastened to solid wood.
Typical distances
- Gable ends: about 6 inches of uncut deck at each end is a common manufacturer spec.
- Ridge meeting a wall or second story: commonly about 12 inches back from the wall.
- Chimneys and junctions with other ridges: often about 12 inches.
- Hips: the slot normally stays on the horizontal ridge; check whether the vent is approved for hips at all, since many are not.
Always follow the instructions printed with the specific vent, since one manufacturer's numbers can differ from another's.
Ridges that extend past the attic
If a ridge continues over a vaulted porch or a separately framed space, the slot should only be cut where there is open attic below it connected to intake vents. Cutting into an area with a finished ceiling or no intake gains nothing and adds a leak path.
Finishing the ends
The vent ends are plugged or capped, then covered with cap shingles. See ridge vent vs box vents, and roof anatomy explained for the names of each roof edge.