How do you install ridge cap on a metal roof?

Exposed fastener panels

1. Closures: outside closure strips shaped to the panel profile fill the gaps under the cap. Use solid closures for an unvented ridge, or vented closures if the ridge is part of the attic ventilation.
2. Sealant tape on top of the closures, and sometimes below them, per the manufacturer.
3. Ridge cap: centered on the ridge, with the legs matching the roof pitch.
4. Fasteners: screws through the cap and closures into the high points of the panel ribs, not into the flats where water runs.
5. Laps: overlap each piece by the manufacturer's amount with a bead of sealant, lapped away from the prevailing wind.
6. Ends: close the cap ends at the gables, usually by notching and folding the metal down.

Standing seam panels

Standing seam ridges avoid putting screws through the panels where possible. Z-closures are fastened to the panel flats over a bed of sealant, and the ridge cap is attached to the Z-closures with rivets or stitch screws. The panel ends are often bent up as a dam before the closure goes on. Vented versions use a profile vent under the cap.

Common mistakes

• Skipping closures, which lets in insects, birds and wind-driven rain.
• Overtightening screws so the washers split.
• Using a cap bent for a different pitch, which leaves gaps at the legs.
• Leaving metal shavings on the panels, which rust stain quickly.

See metal roofing in Georgia and ridge vent vs box vents.