How to Install Standing Seam Metal Roofing: Clips, Seams and the First Panel

Step by Step

1. 1Step 1: Prepare the deck, underlayment and eave line

   Standing seam needs a flat, solid deck, typically 5/8 inch plywood or as the manufacturer requires. Install high-temperature underlayment with a slip sheet if specified, then the eave trim and closures. Check the fascia and eave line with a string. Any bow in the fascia will show in the panel ends.

   Also install rake trim to the detail in the manual, and confirm the roof is square by measuring diagonals across each plane. An out of square roof has to be split between the eave and the rake, or corrected with trim, before the first panel goes on.

2. 2Step 2: Square and set the first panel

   Measure from the ridge and from the eave to establish the line for the first panel, and verify it is square to the eave with a 3-4-5 check or diagonal measurements. Start at a rake on a gable roof, or at the centre of a hip roof so the partial panels are symmetrical. The first panel sets the geometry for every other panel.

   Place the panel so its lower end overhangs the eave by the amount in the manual, usually about 1-1/2 inches, and hem or notch the end as the eave detail requires. Do not fasten yet. Check the overhang, the rake gap and the seam alignment, then clip it. On a long roof, re-measure the panel's coverage from the rake at the ridge end and the eave end. A difference of over 1/8 inch means a correction now, not later.

   Watch out: Do not trust the roof edge. Fascia and rake boards are rarely straight. Square the first panel to the roof geometry and deal with the difference with trim.

3. 3Step 3: Set clips in fixed and floating zones

   Clip spacing depends on panel, gauge, wind load and substrate, and commonly runs 12 to 24 inches on centre along the seam, with closer spacing at eaves, rakes and ridges where wind uplift is higher. Follow the manufacturer's clip layout and the engineered wind load for your area.

   Most systems use a fixed clip near the ridge or at a designated row to anchor the panel, with sliding or floating clips down the slope. The panel grows and shrinks from the anchor point. A fixed clip at the eave and a fixed clip at the ridge trap the panel and cause oil canning, buckling or noisy ticking. See how to allow for thermal movement for the reasoning.

   Tip: Never overdrive clip screws. The clip must slide freely under the panel, so screw heads should be snug, not crushing the clip flange.

4. 4Step 4: Engage the next panel over the first panel's clips

   Set the panel with its overhang at the eave matching the last one and press the seam into engagement, working from the eave to the ridge. On a snap-lock seam, you will feel and hear the click. On a mechanical seam, the two legs sit together ready for the seamer.

   Check that the panel stays straight. Stand at the eave and sight up the seam line to catch drift. Re-measure the coverage width at the ridge end every few panels and correct by moving each new panel a small amount, never in one big jump. Clip the new panel's far side as you go.

5. 5Step 5: Seam the panels closed

   Mechanically seamed panels are closed with a seaming tool, which folds the standing legs together. Electric seamers ride the seam and give a consistent lock, and hand crimpers are used at ends and in tight spots. Fold to the profile's stated seam: a single lock or a double lock, depending on the slope and manufacturer.

   Seam from one end in a continuous pass and check the result visually. The machine itself is covered in how to use a mechanical seamer. A seam that is open in places will leak or chatter. Keep the machine clean of metal shavings so it does not scratch the paint. If the seam has a factory sealant bead, confirm it is in place and continuous before seaming.

6. 6Step 6: Cut, hem and fit the panels at the eave and ridge

   At the eave the panel is usually hemmed or folded to form a drip edge that keeps water off the fascia. At the ridge the panel top is turned up into an end dam or hemmed to sit inside the ridge closure. Hemming and bending panel ends covers the method, including notching the seam leg without splitting the panel.

   Cut panels with shears, nibblers or a power shear, not an abrasive blade. Hot abrasive dust embeds in the paint and rusts within weeks. See cutting metal roof panels.

7. 7Step 7: Flash penetrations, walls and valleys as you go

   Pipe boots, curbs and skylights need the panels cut and lapped around them, with the upslope panel lapping over the flashing and the downslope panel under it. Follow the shingle-style lap so every joint sheds water out and away. See flashing pipes on metal roofs, metal roof valleys and wall flashing.

   Seal where the manufacturer says to, with butyl tape and sealant in the lap. Keep screws out of the water path.

8. 8Step 8: Finish the ridge, hips and rakes

   The ridge cap closes the top of every panel and needs a closure shaped to the profile, vented or not depending on the roof design. See ridge and hip caps and rake trim.

   Finish by sweeping every metal shaving off the roof, because shavings rust and stain the paint. Touch up scratches and cut edges with matched paint, and walk the roof to check for loose clips and open seams.

Oil Canning: Causes and Prevention

Fraser Valley Notes

Common Mistakes

• An unsquare first panel. The error grows up the roof and ends as a crooked gap at the ridge and rake.
• Fixing clips in both the eave and ridge rows, which traps the panel and causes buckling or noise.
• Overdriving clip screws so the clip cannot slide.
• Cutting with an abrasive wheel, leaving hot particles that rust on the finish.
• Seaming before the panels are aligned, locking in a crooked line.
• Leaving metal shavings on the roof, which rust and stain the paint.
• Wrong clip spacing at the eaves and rakes, where wind uplift is highest.