How are ridge caps cut for a roof?
Short answer. On 3-tab roofs, ridge caps are traditionally made by cutting each 3-tab shingle into three pieces at the slots, then tapering the top corners so the covered part is narrower than the exposed part. Architectural shingles should not be cut for ridges; manufacturers make dedicated hip and ridge shingles, and enhanced warranties typically require them.
The traditional 3-tab method
- Turn the shingle face down and cut through it at each slot line to make three roughly 12 by 12 inch pieces.
- From the top of each slot cut, trim each upper corner at an angle so the top portion is narrower. The tapered part gets covered by the next piece and lies flat without bulky corners.
- Bend each piece over the ridge, centered, with the granule side up.
- Install with the exposed end facing away from the prevailing wind, each piece overlapping the last so roughly 5 inches stays exposed.
- Nail each piece with two nails in the area the next piece will cover, about an inch in from each side.
- Seal the exposed nails on the final piece.
Why not cut architectural shingles
Laminated shingles are two layers bonded together. Bent over a ridge they can crack and separate, and their thickness makes a lumpy ridge. Manufacturers sell matching hip and ridge products designed to bend, carry wind ratings, and qualify for system warranties.
Practical cautions
- In cool weather, shingles crack when bent; warm them first or use flexible ridge products.
- Over a ridge vent, use nails long enough to penetrate the vent and deck as the vent instructions require.
- Ridges catch the highest winds, so nail placement matters more here than anywhere.
For how the ridge fits into airflow, see ridge vent vs box vents, and for roof terms, roof anatomy explained.