Installing corrugated metal roofing panels is a manageable DIY project for someone with basic construction skills and comfort working on a roof. The work is straightforward compared to tile or complex shingle systems: panels are large, lightweight, and attach with a single fastener type. This guide covers a complete installation from underlayment to ridge cap for a standard gable roof.

Tools and Materials You’ll Need

Tools:

• Cordless drill with 5/16-inch hex driver bit for roofing screws
• Metal snips (aviation-style left and right) for cutting panels
• Circular saw with a fine-tooth metal blade (or carbide blade run backwards) for long cuts
• Chalk line for alignment
• Measuring tape and marker
• Safety glasses and work gloves (cut metal edges are sharp)
• Rubber-soled shoes for roof walking
• Ladder and, for steeper pitches, roof jacks

Materials:

• Corrugated metal roofing panels (26 gauge)
• Ridge caps (for gable roofs)
• L flashing for eave drip edge and rake trim
• Roofing screws: #10 or #12 × 1.5 inch self-drilling hex-head with 5/16-inch washer head and EPDM rubber washer
• Foam closure strips (inside and outside profiles for your panel corrugation)
• Butyl tape or roofing sealant
• 30-lb roofing felt or synthetic underlayment

Step 1: Prepare the Roof Deck

Inspect the roof deck (plywood or OSB) for rot, damage, or soft spots. Replace any compromised decking before proceeding. The deck must be flat, solid, and fully nailed.

Install underlayment starting at the eave, lapping each course over the one below by at least 4 inches. Staple or nail the underlayment in place; it just needs to stay put during panel installation. At the ridge, fold the underlayment over and staple to the other side.

Step 2: Install Eave Drip Edge Flashing

Before laying the first panel row, install eave drip edge (2×2 L flashing) along the eave. The drip edge goes over the underlayment, with the horizontal leg on the deck and the vertical leg hanging down in front of the fascia. This directs water off the panel edge into the gutter rather than letting it run back behind the fascia.

Use roofing nails at 12-inch intervals. Lap sections of drip edge 2 inches at joints.

Step 3: Install the First Panel

Start at one lower corner of the roof. Position the first panel with the corrugation running up the slope (perpendicular to the ridge), aligned with the rake (gable end). Allow 1 to 1.5 inches of overhang beyond the eave edge for water shedding.

Before fastening, snap a chalk line parallel to the ridge at the location of the first purlin above the eave. This gives you a straight reference for screw placement across the panel width.

Fasten at every corrugation valley where the panel crosses a purlin. For panels on solid decking, fasten every 12 inches along the eave edge (where panels are most vulnerable to wind lift), every 24 inches in the field, and every 12 inches at the ridge.

Screw torque: Drive screws until the EPDM washer compresses and spreads slightly beyond the washer ring — you should see the rubber squeeze out just a little. Don’t overdrive (crushes the washer) or underdrive (leaves a gap).

Step 4: Install Successive Panels

Each panel overlaps the previous by one full corrugation (the last corrugation of one panel overlaps the first corrugation of the next). Push the panels together so they seat fully, with the top panel’s corrugation nested over the bottom panel’s last corrugation.

Check alignment periodically by measuring from the ridge to the eave at multiple points — panels that gradually walk out of parallel will create a gap or overlap problem at the far end.

On very long roofs, apply a bead of butyl tape at the side lap before closing the overlap. On shorter roofs in Sacramento’s dry climate, this is often omitted, but it provides insurance against wind-driven rain infiltration.

Step 5: Trim the Last Panel at the Rake

At the far gable end, the last panel will likely need to be cut lengthwise to fit within the rake edge. Measure the remaining width, mark on the panel, and cut with metal snips or a circular saw with a fine-tooth metal blade. Cut edges are sharp — de-burr with a file if anyone will be working near them, and treat the cut edge with zinc-rich cold galvanizing compound to protect the exposed steel.

Step 6: Install Rake Trim

L flashing along the gable rake edges covers the panel edge and creates a clean finish. Position the flashing with one leg over the panel surface and one leg down the fascia of the gable end. Fasten through the leg on the panel face at 12-inch intervals with roofing screws.

Step 7: Install Closure Strips at the Ridge

Before installing the ridge cap, apply inside closure strips to the top corrugation of each panel at the ridge. These foam strips fill the corrugation gaps between the panel top edge and the flat underside of the ridge cap. Without closure strips, the ridge has open gaps large enough for birds, bats, and wind-driven rain.

Press the closure strips firmly into the corrugations. Some installers also apply a bead of sealant along the strip-to-panel interface for additional weathertightness.

Step 8: Install Ridge Cap

The ridge cap goes over the top edges of panels from both sides, spanning the ridge. Position the cap so it overhangs the gable ends by 1 inch on each side. Fasten through the cap and into the panel beneath with ridge cap screws at every corrugation valley.

Where two ridge cap sections meet on a long ridge, overlap them by at least 6 inches with the upper-slope piece on top. Apply butyl tape or sealant at the overlap.

Step 9: Flash Any Penetrations

Pipe boots, exhaust fan flashings, and any other penetrations should be flashed with appropriate metal or rubber boot flashings. The flashing must integrate with the panel overlaps — flashing above the panel directs water over the panel; flashing beneath the panel directs water under the panel and to the next lap. The upslope side should always be tucked under the panel or flashing above it.

Frequently Asked Questions

How many screws per panel?

Approximately one screw per corrugation valley at each purlin crossing, plus additional screws at eave, ridge, and side laps. A typical 10ft panel on a roof with purlins at 24-inch centers gets approximately 5–6 screws per valley row = 30–36 screws per panel for a 36-inch wide panel with 11 corrugations, less for sparser fastening patterns in the field.

Can I install panels on an existing shingle roof without tearing off?

Yes, in many cases. Install horizontal furring strips over the shingles to provide a flat fastening surface and prevent the panel corrugations from telegraphing the irregular shingle surface. Check local building codes for requirements on re-covering existing roofing.

How do I cut corrugated panels?

For cross-cuts (across the corrugation width): use metal snips for short cuts; a circular saw with a fine-tooth carbide blade for long cuts across multiple panels. For rip cuts (along the length of the corrugation): a circular saw or angle grinder with a metal cutting disc. Always wear safety glasses and work gloves when cutting metal panels.

What do I do about rust at cut edges?

Apply zinc-rich cold galvanizing compound (spray or brush) to all cut edges immediately after cutting. This protects the exposed steel cross-section from corrosion. Follow up with touch-up paint matched to the panel color for a clean appearance.