What is the difference between a ridge vent and a ridge cap, and how do you vent a ridge cap?
Ridge cap
Every shingle roof has ridge cap, vented or not. It covers the joint where two slopes meet and the top edges of the field shingles. Architectural shingle systems use thicker preformed hip and ridge shingles, which resist cracking when bent over the peak and match the look of dimensional shingles. Cutting three-tab shingles into caps is an older method that usually does not suit a dimensional roof.
Ridge vent
The vent is a rigid plastic or fiber mat that lifts the cap shingles about an inch above the deck, with a filter along the edges. Air exits sideways between the cap and the field shingles.
How to vent an existing ridge cap
- Remove the existing cap shingles.
- Cut the deck slot on each side of the peak to the vent's specified width, stopping short of the ends.
- Install the ridge vent full length and plug the ends.
- Nail new cap shingles over it with longer nails that reach through the vent and deck.
- Close off other exhaust vents in that attic and confirm intake.
Things to know
Old cap shingles usually cannot be reused, and new caps on an older roof may not match the faded field color exactly. Check that the cap shingle is approved for use over the vent. See architectural vs 3-tab shingles and roof anatomy explained.