Ridge caps and flashing are what separate a metal roof that works from one that leaks. Getting these details right during installation prevents the most common sources of water infiltration on corrugated metal roofs. These tips apply to 26 gauge corrugated metal panels in Sacramento and Northern California where wind-driven rain and intense UV exposure test every installation.

Ridge Cap Installation

The ridge cap covers the peak where two roof planes meet at the top of a gable roof. Before installing the ridge cap, the last row of panels on each side should be installed with their top edges meeting or slightly overlapping near the peak. Do not leave a large gap at the ridge — the ridge cap only needs to lap down a few inches on each side to provide adequate coverage.

Apply closure strips along the top edge of the panels on both sides of the ridge before placing the ridge cap. Outside closures are pre-formed foam that matches the corrugated profile, fitting between the panel top and the underside of the ridge cap. These closures prevent insects and water entry at the peak. Secure them with a compatible adhesive or butyl tape before placing the ridge cap over them.

Set the ridge cap so it laps equally down each roof plane. Fasten with roofing screws through the ridge cap, through the closure strip, and into the panels or purlins below. Space screws at 12 to 24 inches on center along each side. Overlap ridge cap sections by at least 6 inches at splices, with the upper section lapping over the lower section (uphill side laps over downhill side).

Eave Drip Edge and L Flashing

The eave drip edge (L flashing) runs along the bottom edge of the roof, directing water into the gutter or away from the fascia board. Install the drip edge before the first row of panels. The horizontal leg of the L flashing should sit flat on the top of the fascia or eave framing, and the vertical leg should hang down in front of the fascia to direct water away.

Fasten the drip edge to the fascia with roofing screws or nails at 12 to 24 inches on center. Overlap drip edge sections by at least 2 inches at joints. When the panels are laid, they should overlap the top leg of the drip edge so water flows off the panel surface and down the vertical leg into the gutter.

Rake Edge Flashing (Verge Trim)

The rake edge is the sloped edge of a gable roof where the roof meets the end wall or gable fascia. Rake flashing (also L-shaped) is installed after the panels to cover the panel edge and the gap between panels and the rake framing. The vertical leg of the rake flashing goes up against the gable fascia, and the horizontal leg laps over the top surface of the panel edge.

Apply butyl tape or compatible sealant between the rake flashing and the panel surface to close the gap and prevent water intrusion at the edge. Fasten the rake flashing through both legs — into the fascia and through the panel edge — using roofing screws. Overlap rake sections by at least 2 inches at joints.

Wall Flashing for Lean-To and Attached Structures

When a metal roof meets a vertical wall (as in a lean-to, carport attached to a building, or roofing running up to a house wall), step flashing or L counter-flashing is needed at the wall connection. The flashing must turn up the wall by at least 4 to 6 inches and be tucked behind the wall siding or sealed against the wall surface to prevent water from running behind the flashing.

Use inside corner L flashing at the base of the wall-to-roof connection. Apply butyl tape or roofing sealant between the flashing and the last panel. Fasten the flashing to both the panel and the wall framing. For masonry or stucco walls, use appropriate anchors and seal the flashing-to-wall joint with a compatible flashing sealant.

Color Matching for a Professional Result

All ridge caps, L flashing (inside corner and 2×2), and trim should match the panel color for a clean, professional appearance. We stock panels, ridge caps, and L flashing in Dark Gray, Brown, White, Matte Black, Blue, and Forest Green. Mismatched colors are one of the most common ways an otherwise good installation looks unfinished.

For current stock on ridge caps, flashing, and corrugated panels near Sacramento, Roseville, Elk Grove, Rancho Cordova, or Folsom, call 916-940-5700 with your panel color, project dimensions, and panel length. We can help you estimate quantities and confirm availability for your schedule.