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Standing Seam vs. Metal Shingles vs. Exposed-Fastener Panels: Three Metal Roofs That Share Nothing But the Word
Roofing
Standing Seam, Metal Shingles or Panels: Pick the Roof, Not the Word
Someone says metal roof and three different roofers hear three different things: one sees a barn, one sees a slate-look shingle, one sees the long clean panels on a modern house. All three are steel, all three last decades, and that is where the similarity ends. Fastening, leak points, what slope they can go on, how they are repaired and what they cost are all different. This is the three of them, laid out.
Side by side
| Exposed-fastener panels | Interlocking metal shingles | Standing seam | |
|---|---|---|---|
| What it looks like | Ribbed or corrugated sheets, 3 ft wide, eave to ridge. A barn, a cottage, an industrial roof. | Pieces 12 to 18 in. wide shaped like shingles, shakes, slate or tile. A traditional house. | Flat panels 12 to 18 in. wide with raised seams every panel, eave to ridge. A modern house, a church, a good cottage. |
| Gauge | 26 or 29 | Sold by system; steel 26 to 28 equivalent, or aluminum | 24 or 26 |
| Fastening | Screws through the face every 12 to 24 in., with neoprene washers | Nails or screws under the next course, hidden | Concealed clips under the seam; snap-lock or mechanically seamed |
| Leak points | Every screw, in year 20 when the washers harden; panel overlaps on low slopes | Flashings; the shingles themselves almost never | Flashings and penetrations only; the seams do not leak |
| Minimum slope | 3/12 (some 2/12 with sealant) | 3/12 to 4/12 depending on the product | 3/12 snap-lock; 1/4 in 12 mechanically seamed |
| Thermal movement | Panels expand against the screws; screw holes elongate over the years | Small pieces, small movement; not an issue | Clips let the panel float; the system is designed for it |
| Walking on it | Fine on the ribs | Fine | On the flat near clips; dents if careless |
| Repair | Easy: replace screws, swap a panel | Replace a piece; need the matching product | Replace a panel from the ridge down; needs a standing-seam roofer |
| Solar later | Rail mounts screwed through | Rail mounts screwed through | Clamps on the seams, no holes |
| Cost per sq ft installed | $8.50 to $13.00 | $11.00 to $18.00 | $13.00 to $22.00 |
| Life | 35 to 45 years with a screw service at 20 to 25 | 50 years | 50 years plus |
Exposed-fastener panels, honestly
The cheapest metal roof and the one most people picture on a farm. It works, it lasts, and it has one flaw that is baked in: thousands of screws through the surface, each with a rubber washer that the sun hardens over 15 to 25 years, each in a hole that the panel’s expansion and contraction slowly elongates. At some point somebody goes up with a drill and replaces every screw with the next size up, which on a house roof is a day and $800 to $1,500, and after that it is good for another 15 to 20. On a cottage, a garage, a barn or a workshop, that is a fine deal. On the house you live in, the concealed-fastener systems are what the extra $3 to $5 a foot buys: nothing through the surface.
Metal shingles, honestly
The metal roof for a house that does not want to look like it has a metal roof. From the street, a good steel or aluminum shake profile reads as cedar or slate; up close you can see the pattern repeat. The pieces interlock on all four edges and fasten under the course above, so nothing is exposed, and they handle a complicated roof (dormers, hips, valleys) better than long panels do, because they are small. Aluminum versions (the Ontario-made ones in particular) do not rust at a cut or a scratch and are the choice near the lake; steel is stiffer and cheaper. The drawbacks: more seams than standing seam, so more places for a sloppy installer to go wrong; a higher minimum slope on most products; and matching a piece in 20 years means the product still being made.
Standing seam, honestly
The roof the other two are measured against. Long panels, raised seams, concealed clips that let the steel grow and shrink with the seasons, and nothing penetrating the surface except the flashings. Snap-lock (the panels click together) is the residential standard and is rated to about 3/12; mechanically seamed (a machine rolls the seam closed on the roof) is the commercial standard, rated down to nearly flat, and costs more. The limits: it wants a simple roof (every valley and dormer is a custom flashing and a lot of labour), it dents if walked on carelessly, it is the most expensive of the three, and it has to be installed by someone who does it regularly, because a hem or a seam done wrong at the eave is where a $35,000 roof leaks. It is also the only one of the three where solar panels clamp on without a single hole.
Which one, for which building
- A modern house, simple roof, long planes: standing seam.
- A traditional house, hips and dormers, that should not look industrial: metal shingles.
- A cottage with a simple gable and nobody to clear snow: standing seam if the budget allows, panels if not; both shed snow.
- A barn, a garage, a workshop: panels, 26 gauge, and budget the screw service at year 20.
- A low slope, 2/12 or 3/12: mechanically seamed standing seam, or a membrane; not panels or metal shingles.
- A house getting solar in the next ten years: standing seam.
- Near the lake, salt air: aluminum metal shingles or aluminum standing seam.
Prices for each on your roof are a minute in the metal roof calculator; what the quote has to name is on the metal roof cost page.
Questions people ask
Is standing seam better than metal shingles?
On a simple roof, yes: fewer seams, no penetrations, solar-ready. On a complicated traditional roof, metal shingles are easier to install well, look right, and cost less.
What is the difference between exposed and concealed fastener metal roofing?
Exposed: screws through the face of the panel with rubber washers that age. Concealed: clips or nails hidden under the next panel or course; nothing through the surface. Concealed costs $3 to $5 a square foot more and is the house-grade system.
Do standing seam roofs leak?
At the seams, essentially never. At flashings, chimneys and skylights, if they were made badly. The installer is the whole question.
Can metal shingles go on a low slope?
Most need 3/12 or 4/12. Below that, mechanically seamed standing seam or a membrane.
Are aluminum metal shingles better than steel?
Aluminum cannot rust, which matters near water and at cut edges; it is softer and dents more easily and costs a little more. Steel is stiffer and cheaper. Both last 50 years inland.
Say which one
Three roofers quoting three systems is not three quotes; it is three roofs. Pick the system for the building first, then get three quotes on that one, with the gauge and the paint on the paper.
Sources and further reading
- Vicwest: Canadian metal roofing panels and standing seam; gauge and finish data sheets.
- Ideal Roofing: Ottawa-made metal roofing, panels and shingles, with the coating warranties on the site.
- Canadian Roofing Contractors Association: the national association; its roofing specifications are what good quotes are written to.
