Installation Guide
How a standing seam roof is installed
Standing seam is a precision system, not a shingle. Ninety percent of failures we are called to look at are not panel failures — they are layout, flashing or thermal-movement mistakes. This is the sequence we roll panels for, and the details that decide whether a roof lasts fifteen years or fifty.
1. Tear off and deck preparation
Strip to the sheathing. Replace anything soft, re-nail loose sheets, and sight the plane from the eave — metal is unforgiving of dips and humps, which read as shadow lines across the finished roof. Fascia and rafter tails get corrected now, not later.
2. Underlayment
Self-adhered high-temperature ice-and-water membrane at eaves (past the interior wall line), valleys, hips, sidewalls and all penetrations. High-temp synthetic underlayment over the remaining field, lapped shingle-fashion. Standard asphalt felt will soften and bleed under a dark panel in July — do not use it.
3. Eave and rake flashings
Drip edge or eave cleat goes on first so the panel hem can lock into it; rake trim follows the panel in most systems. The rule never changes: every piece laps so water runs out, never in.
4. Panel layout
Measure the roof, divide by the panel module, and decide where the seams land before a single panel goes up. Centre the layout on a dominant feature — a dormer, a chimney, the front elevation — so the last panel is not a two-inch sliver at the most visible rake. Chalk the module lines and mark clip rows.
5. Clips and thermal movement
Clips are concealed under the seam, screwed to the deck, spaced per the wind-load table for the building. On panel runs beyond roughly 30 ft use floating (two-piece) clips with a defined fixed point — usually at the eave or ridge — so the panel can grow and shrink. Pinning a long panel at both ends causes oil canning, seam distortion and eventually fastener tear-out.
6. Setting and seaming panels
Square the first panel to the eave and hem it into the cleat. Work across, engaging each panel into the previous seam. Snap-lock systems are pressed home by hand; mechanical lock panels are run with a hand seamer to start and an electric seaming machine down the run — 90° on the first pass, 180° on the second for a double lock.
7. Valleys, penetrations and sidewalls
Open W-valleys with hemmed panel edges are the durable detail — never close a valley with sealant alone. Stacks and vents get a curb or a high-temp boot, always with a diverter or up-slope flashing so water parts around the penetration. Sidewalls get a counter-flashed Z-flashing tucked behind the cladding, not caulked to it.
8. Ridge, hip and closures
Panel ends are folded up at the ridge (or closed with Z-closures) so wind-driven water cannot run back under the cap. Add vented closure where the attic needs to breathe, then set the ridge or hip cap over the seam line with fasteners kept out of the drainage path.
9. Final walk
Pull every stray screw and steel filing off the roof and gutters — left overnight they rust and stain a brand-new finish. Check seam engagement along each run, confirm all closures are set, and touch up cut edges on exposed trim.
Panels and flashings, made to your measurements
We roll panels to length and fabricate the matching flashings and trims so the details above actually go together on site. If you are deciding between systems, start with mechanical lock or the TSS-3000 profile.
Frequently asked questions
Can standing seam be installed over existing shingles?
We do not recommend it. Going over old shingles hides deck rot, creates an uneven substrate that telegraphs through the panel, adds weight, and voids most manufacturer warranties. Tear off to the deck.
What underlayment should be used under standing seam?
A high-temperature self-adhered ice-and-water membrane at eaves, valleys and penetrations, with a high-temp synthetic underlayment over the field. Standard asphalt-based felt cannot handle the temperatures under a metal panel and will bleed.
How far apart should the clips be?
Clip spacing depends on panel width, gauge, building height and local wind load. As a starting point, 12–24 in on centre in the field with tighter spacing at perimeters and corners. We supply a clip layout with every panel order.
Do panels need room to expand?
Yes. Steel moves with temperature, and on runs over roughly 30 ft you need floating clips and a fixed point so the panel can travel. Pinning both ends is the single most common cause of oil canning and seam distortion.
Snap-lock or mechanical lock?
Snap-lock is faster and fine on steeper roofs in sheltered locations. Mechanical (double) lock is the right call for low slopes, long runs, exposed sites and anywhere snow sits. See our mechanical lock page for the detail.
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