What does a ridge vent detail on a metal roof look like, layer by layer?
Short answer. A typical metal roof ridge vent detail, from the deck up, is a slot cut in the decking at the peak, underlayment lapped up to the slot, the metal panels stopping short of the peak, vented closures or Z-closures with a weather filter across the panel ribs, sealant at the closures, and a ridge cap fastened to the closures rather than through the panel flats. The panel manufacturer's drawing for your profile is the final word.
Layer by layer
- Deck slot: cut along the peak to the width the system calls for, stopped short of the ends like a shingle ridge vent.
- Underlayment: run up each side to the edge of the slot without covering it.
- Panels: installed up each slope, ending a set distance from the peak so the cap can cover the gap.
- Closures: on exposed fastener panels, vented profile closures shaped to the ribs. On standing seam, metal Z-closures fastened to the panels, often with a vented filter strip behind them.
- Sealant or butyl tape: under the closures, sealing them to the panel so wind-driven rain cannot get under.
- Ridge cap: fastened to the closures or Z-closures, with lapped and sealed joints between cap pieces.
- End closures: at gable ends, the cap ends are closed off or hemmed and sealed.
Why standing seam uses Z-closures
Standing seam panels are designed to move with heat. Fastening the cap through the panel flats would pin them and create leak points. Z-closures let the cap attach while the panels float.
Common detail mistakes
- Solid foam closures where vented ones were specified, which kills the airflow.
- No sealant under closures.
- Cap fasteners driven through the vent filter, crushing it.
- Slot cut wider than the cap covers.