How do you install a ridge cap, including a metal ridge cap?
Short answer. On shingle roofs, ridge cap shingles are bent over the peak and nailed one at a time, starting at the end away from the prevailing wind, with each piece overlapping the last by the exposure printed on the bundle and fastened with nails long enough to reach the deck. Metal ridge caps are screwed down over foam or vented closure strips, lapped away from the prevailing wind and sealed at the laps.
Shingle ridge caps, step by step
- Prepare the ridge. If there is a ridge vent, cut the slot in the deck to the vent maker's width and install the vent first.
- Snap guide lines on both sides of the peak so the caps run straight.
- Choose the starting end. Begin at the end opposite the prevailing wind so the exposed edges face away from it.
- Set and nail. Bend each cap over the ridge, align it with the lines, and nail in the area the next cap will cover. Over a ridge vent, the nails must be longer so they pass through the vent and into the deck.
- Keep the exposure. Use the exposure printed on the cap bundle for every piece.
- Finish the end. Cut the last cap to fit, face-nail it, and seal the nail heads.
In cool weather, caps can crack when bent, so warm them first or work in the afternoon. Purpose-made hip and ridge caps bend more reliably than cut-up shingles.
Metal ridge caps
- Install closure strips under the cap that match the panel profile, solid where no venting is wanted and vented where the ridge exhausts the attic.
- Fasten through the cap into the panels or structure with gasketed screws at the spacing the panel maker specifies.
- Lap cap sections away from the prevailing wind and seal the laps with the recommended sealant.
- On standing seam roofs, follow the manufacturer's ridge detail, since panels must still be able to expand and contract.
For how the ridge works with attic airflow, see ridge vent vs box vents, and for the parts of the roof involved, roof anatomy explained.