What Standing Seam Roofers Do That a Shingle Crew Does Not

A standing seam roof can look perfect the day the crew leaves. It can still be put on wrong.

The panels are straight. The seams line up. Nothing leaks. Then a hot afternoon follows a cold night. The flat parts of the panels start to ripple. Or the roof ticks and bangs as the sun comes up.

Sometimes that’s just metal being metal. Sometimes it comes down to how the roof was held down. That’s the main difference between standing seam roofers and a shingle crew. It’s also the reason to hire for it. Still deciding whether a standing seam metal roof is right for your house? Start there, or read how standing seam panels are built. This post is about the people who install it.

The Panel Has to Move

A shingle is nailed down where it sits, and it stays there. A standing seam panel can’t be treated that way. A long steel panel grows and shrinks with every change in temperature. A roof in full sun also gets much hotter than the air around it.

On most systems, a standing seam roofer fixes each panel at one place and lets the rest of it slide. The exact detail comes from the panel maker’s instructions. The Metal Construction Association’s guide to standing seam clips puts it plainly: “Panels must be adequately fixed to the building structure at a single location to resist such forces.” The fixed point controls which way the panel moves. It also stops the panel from creeping down the roof. On most clip-fastened systems, the clips along the rest of the panel let it move.

A crew that fastens a panel solid at both ends, or pins it where the maker didn’t call for a fixed point, takes away that movement. The steel still has to go somewhere. That is one cause of buckling, noise and waviness. Ask any metal roofing crew, including us, where each panel is fixed and what lets it move.

Clips, Spacing and Seams

Most standing seam panels are held by clips hidden under the seams, not by screws through the face. Some systems use slotted fastening strips instead. Either way, the hidden fastening is most of the skill.

Clip spacing isn’t one number. The wind pulls hardest at the edges and corners of a roof. The MCA says clip spacing comes from an engineering design called a clip analysis. It’s set for each zone: “field of roof, leading/trailing edges and outside corner zones”. A good roofer follows the panel maker’s instructions for the wind loads on your house.

Clips and panels belong together. The MCA says panels and clips from different systems should only be mixed “after engineering evaluation done by a registered design professional and/or testing.” Ask what clip goes with the panel being quoted.

The seam is closed on the roof. Many standing seam systems “call for hand seaming (or crimping) at clips, followed by mechanical seaming for the full length of the panel.” On those systems, that means a hand tool at every clip, then a seaming machine along each seam. Snap-lock panels are the exception: they click together without a machine. The MCA warns that bad seaming “can completely downgrade the wind uplift capacity of the roof system.”

A shingle roof has no clips and no seams to close. Standing seam takes different tools, and a crew that has done it many times.

Not Every Roof Is Steep Enough

Each standing seam product has its own lowest slope, set by the panel maker. The building code and the rest of the roof assembly also apply. Two examples: a roofing practices manual entry for one snap-lock panel) asks for “a minimum roof slope of 1:6 (2″ in 12″)”, while another maker’s installation guide rates its mechanically seamed panel for “slopes 1:12 or greater with mastic.”

The right answer for a low porch roof or a shed dormer depends on the panel. A standing seam roofer checks each section of your roof against the product. If one section is too flat, they’ll tell you before they quote. Before you accept a quote for standing seam metal roofing, ask which sections of your roof the panel is rated for.

Flashing, Trims and Skylights

On a shingle roof, much of the flashing is tucked under the next course of shingles. On a standing seam roof, the trims are part of the system. One panel maker’s guide says it’s “highly recommended that all trims and flashings be of the same material as the panels (metal, gauge, finish)”. Mismatched trim can weather and move differently from the panels.

Openings take real time. One expert member on Green Building Advisor put it this way: “Flashing a skylight properly will take about the same time as doing an entire roof surface.” That’s one person’s estimate, and every roof is different. Skylights, chimneys and vents are the details that take care. Ask how each opening on your roof will be flashed.

The layer under the steel matters too. On a house roof, standing seam usually goes over an underlayment. A steel roofing supplier’s summary of a CSSBI fact sheet notes that this layer “plays a critical role in controlling the migration of condensation” under the metal. It doesn’t stop condensation on its own: air sealing, insulation and the attic design matter too. On a standing seam metal roof, ask what goes under the steel, not only which panel goes on top.

What Good Installation Cannot Promise

One thing a standing seam roofer cannot honestly promise you: a roof with no oil canning at all.

Oil canning is “visible waviness in the flat areas of metal roofing.” The MCA’s technical bulletin on oil canning says “no panel manufacturer, fabricator, or installer can assure the total prevention of oil canning on any given project.” It adds that oil canning “is generally an aesthetic issue. Structural integrity is typically not affected.”

What installation does control is the part that makes it worse. The same bulletin names one cause: panels that can’t expand because of “perimeter flashing conditions or inadvertent ‘dual pinning'”. That’s the fixed-point work from the start of this post. A roofer who says oil canning never happens on their roofs is promising too much. A roofer who explains how the panels stay free to move is telling you what they control. Want that conversation about your roof? See our standing seam metal roof installation page and ask us.

What 705 Roofing Does

We install standing seam on houses in Simcoe County, Georgian Bay and Muskoka. This summer that included a snap-lock standing seam roof in Phelpston. We install Canadian-made panels, and the panel maker warrants the paint finish. Every new metal roof we put on carries our 10-year workmanship warranty. We are WSIB cleared. Our roofing warranty page explains what each warranty covers.

Standing Seam Roofer Questions

Can any roofer install standing seam?

Any roofer can try. The work isn’t like shingles. Most panels need a fixed point, the hidden fastening follows the maker’s instructions, and mechanically seamed panels are closed the way the maker specifies. Snap-lock panels click together. Ask how many standing seam roofs the crew has done and which seaming tools they use.

Do standing seam roofs need a seaming machine?

Mechanically seamed panels are usually closed with a seaming machine, or with hand tools where the maker allows it. Many systems call for hand seaming at each clip first. Snap-lock panels click together without a machine.

Is oil canning a sign of a bad install?

Not always. Some waviness can happen on any flat metal panel, and it is usually cosmetic. Heavy waviness along flashings or fasteners can point to panels that were held too tight to move.

What should I ask a standing seam roofer before I hire them?

Ask one question: “Where is the fixed point on each panel, and how does the rest of it move?” A roofer who does this work every day can answer it for the exact panel they’re quoting.

If you are planning a metal roof, read about standing seam metal roofing and send us a request for a free quote.

Related service: standing seam metal roofing