What is metal roof edge flashing, and how is it installed?
Short answer. Metal roof edge flashing is the trim along the eaves and rakes: an eave trim or drip edge that directs water into the gutter and protects the deck edge, and a rake or gable trim that covers the panel edge and locks it down against wind. Eave trim goes on before the panels with the underlayment lapped over it, while rake trim goes on after the panels and is fastened to the panel and the rake.
Eave trim
- Installed first along the eave, over the fascia and onto the deck.
- The underlayment laps over the top of the eave trim, so water on the underlayment drains onto the metal.
- Panels overhang the trim slightly toward the gutter, so water clears the edge.
- On standing seam, the panel end hooks over a cleat or hemmed edge on the eave trim; on exposed-fastener panels, an eave closure seals the gaps under the ribs.
Rake trim
- Installed after the panels, covering the edge of the outermost panel and the rake board.
- Fastened into the panel rib or to a cleat on standing seam, and into the side of the rake.
- Laps run from the eave upward, upper piece over lower, with the top end tucked under the ridge cap.
Edge problems to watch for
- Blow-offs. Wind uplift is strongest at rakes and eaves. Rake trim fastened only into the fascia, or with fasteners spaced too far apart, can peel in a storm.
- Water behind the gutter. Missing eave trim or panels cut short let water run down the fascia.
- Reverse laps at the eave, with underlayment tucked under the trim.
- Loose or wavy trims from fasteners overdriven or placed without room for expansion.
- Mismatched metals where trims meet copper or other incompatible materials.
Edge details vary by panel system and are usually tied to wind ratings and the warranty. See metal roofing in Georgia and drip edge explained.