Metal costs two to three times what asphalt costs, and lasts two to three times as long. Once you notice that the two ratios are roughly the same, the cost-per-year comparison stops being interesting — the two products land close enough that it cannot decide anything.
What decides it is a different set of questions. Price first, then those.
Installed cost, per square
| Roof | Typical installed per square | Service life |
|---|---|---|
| 3-tab asphalt | $300 – 500 | 15 – 20 yr |
| Architectural asphalt | $400 – 750 | 25 – 30 yr |
| Exposed-fastener metal (ag panel, R-panel) | $350 – 700 | 25 – 40 yr |
| Standing seam steel, 24–26 ga | $900 – 1,600 | 40 – 60 yr |
| Standing seam aluminium | $1,100 – 1,900 | 50 – 70 yr |
| Stone-coated steel tile | $800 – 1,400 | 40 – 50 yr |
Typical US contractor pricing at the time of writing, not quotes. On a 21-square roof that is roughly $8,400–15,750 in architectural asphalt against $18,900–33,600 in standing seam.
Service lives assume the roof is installed correctly and ventilated. An unventilated attic shortens asphalt life materially and does metal no favours either — see soffit intake vs exhaust balance.
Cost per year, which settles nothing
Take the midpoints:
- Architectural asphalt: ~$575/square over ~27 years = $21 per square per year
- Standing seam steel: ~$1,250/square over ~50 years = $25 per square per year
- Exposed-fastener metal: ~$525/square over ~30 years = $18 per square per year
Three numbers within a few dollars of each other, built on ranges far wider than the gaps between them. Anyone presenting cost-per-year as the argument for either material is presenting noise. The same comparison across all materials is in cost to replace a roof by material.
The questions that do decide it
How long are you staying? This is the big one. Metal's advantage is entirely back-loaded — it arrives in year 30, when the asphalt roof needs replacing and the metal one does not. If you sell in year 8, you paid for 50 years of roof and used 8. Asphalt's 25–30 years is longer than most people own the house; see how long does an asphalt roof last.
Does it pay back at sale? Partially, not fully. Metal reads as an upgrade to buyers and appraisers, but the premium recovered at sale is typically well under what the upgrade cost. Treat resale as softening the difference, not erasing it.
What does your insurer say? In hail and wind states some carriers discount for impact-rated roofing, and Class 4 impact-rated products exist in both metal and asphalt. The discount is real but usually modest — worth a call to your agent before deciding, not worth assuming.
Can it go over the existing roof? Metal often can, over one layer of asphalt, on purlins or a slip sheet, where code allows. That skips the tear-off and the disposal, which is a meaningful chunk of the gap. It also hides whatever the deck is doing — see tear-off vs roofing over and roof decking replacement cost before choosing it.
What is the pitch? Standing seam handles low slopes that asphalt cannot — down to 1/4:12 for some mechanically-seamed profiles, where asphalt needs 2/12 minimum with doubled underlayment and really wants 4/12. On a low-slope section metal is not a preference, it is the answer. See minimum roof pitch for shingles.
Two things that are not real
"Metal roofs are noisy in rain." Over solid decking with underlayment — which is how residential standing seam is installed — a metal roof is not measurably louder inside than asphalt. The noise reputation comes from barn roofs screwed to open purlins with nothing underneath.
"Metal attracts lightning." It does not. It is not more likely to be struck, and being non-combustible and conductive, it is a better material to be under if it is.
Where each one wins outright
Asphalt wins when you are staying under 15 years, when the roof is cut-up with many valleys and dormers (metal's labour cost climbs fast with complexity), or when budget is the binding constraint and the alternative is deferring the job.
Metal wins on low slopes, on simple gable and shed roofs where panels run long and clean, in wildfire country where non-combustible matters, and when this is the forever house and you would rather buy the roof once.
The short version
Expect to pay 2–3× asphalt for standing seam and get 2–3× the life. Cost per year is a wash. Decide on how long you are staying, the pitch, and how complicated the roof is — those three separate the two materials in a way price per year never will.