A metal roof lasts substantially longer than asphalt shingles and handles hail differently, denting rather than fracturing, while asphalt costs less up front and is easier to match in an established neighbourhood. The Metal Construction Association’s field study of standing seam roofs in service for up to 35 years concluded that “the expected service life of a similar roof constructed today in a wide range of environments using best practices can be expected to be in excess of 60 years.” For an Alberta homeowner, the decision usually turns on two questions: how long you plan to stay, and how much hail exposure your area gets.
Here is what the evidence actually shows on lifespan, hail performance, noise, and energy, so you can compare the two on facts rather than on sales claims.
How long does each roof actually last?
The Metal Construction Association inspected 14 low-slope, unpainted 55% Al-Zn alloy-coated steel standing seam roofs across North America with up to 35 years of service, and had the panels, components, and sealants analysed in independent laboratories.
Its findings were specific. The steel panels themselves “have weathered uniformly with corrosion rates that conservatively project flat panel service lives ranging from 60 to 375 years for an AZ55 coating, depending on the local precipitation pH. In all but the worst case, coating life is 79 years or more.”
The limiting component was not the metal. It was the sealant: “Butyl sealant life will be the deciding factor in establishing end-of-life for these roof systems.” Even on roofs 26 to 35 years old, the study judged sealant performance “entirely adequate and without issue,” and projected sealant service life conservatively at 60 years.
Two qualifications matter when applying this to a house. That study examined low-slope commercial roofs, not residential steep-slope installations, and it examined unpainted Galvalume rather than the painted panels typically used on homes. What it establishes reliably is that the metal itself is not the wear component. Asphalt shingles, by contrast, wear out by design as they shed the granule layer that protects them from UV.
The MCA study also flagged that ancillary components age faster than panels: “On many of the sites, ancillary roof components have begun to rust and exhibit inferior service lives that could negatively impact the service life of panels with which they are in contact.” It found 300 series stainless steel fasteners and cinch plates aging well, while 400 series stainless fasteners showed varying corrosion depending on site. The specification of the fasteners on your roof is not a detail to leave to the installer’s default.
Which handles Alberta hail better?
This is the question that matters most in central and southern Alberta, and it has been studied directly.
Koontz and White presented a study to the RCI (now IIBEC) International Convention in 2014 that impacted ten metal roofing targets, in corrugated, standing seam, and R-panel profiles at different gauges, with both steel spheres per UL 2218 and ice spheres per National Bureau of Standards Building Science Series 23.
The laboratory result: “With the exception of a 32-gauge corrugated metal penetration, splitting of the metal did not occur with any of the metal roofing tested.” Indentations occurred in all metal roofing tested, with depth and width varying by impact location, gauge, and metal type. Higher yield strength steel proved less vulnerable to indentation.
The field data is more useful still. The study draws on two Roofing Industry Committee on Weather Issues hail investigations. In Oklahoma City in 2004, six metal roofs impacted by hail reported at 1 to 2.5 inches were examined: “the hail-caused dents were found to be a cosmetic issue, with no functional damage to the paint or the metal plating. On exposed fastener systems, there were no instances found of fasteners loosened by hailstone impacts. Panel joints had not been distorted sufficiently to affect the water-shedding ability of the panels.” In Dallas in 2011, sixteen metal roofs were examined after hail reported at 1 to 4 inches: nine showed no dents at all, and there were “no fractures, spalling, or punctures” and “no evidence of leakage within any of the metal roofs.”
Over 50 years of examining metal roofs after hail events, the authors report that “fewer than ten metal roofs have actually been punctured or split by hail impact,” and that “long-term corrosion or deterioration of metal roofs at the points of impact has not occurred. Minor impacts or dents have no effect on the long-term performance of metal roofing systems.”
The honest counterpoint is aesthetic. The study acknowledges that “aesthetic concerns may be a consideration for steep-sloped metal roofing when hail dents are visible from the ground.” A dented metal roof still sheds water; it may not still look new.
Asphalt shingles fail differently. Hail knocks granules off, exposing the asphalt to UV, which shortens the life of the roof even when it does not leak that season. That is why impact-resistant asphalt exists as a separate rated category.
What does impact resistant actually mean?
Both materials are tested against the same standards, so you can compare them directly.
UL 2218 Class 4, the top rating, requires dropping a 2-inch diameter steel sphere from 20 feet, producing 23.71 ft-lbf of impact energy, equivalent to a 2-inch hailstone at terminal velocity, with two impacts at the same location. Factory Mutual’s FM 4471 uses a different scale, and as the IIBEC study notes, “the impact energy of the resultant FM Severe hail rating is less than the UL 2218, Class 4 impact energy.” The two ratings are not interchangeable.
The City of Calgary’s Resilient Roofing Rebate Program accepts Class 4 systems meeting either UL 2218 or FM 4473, and its list of acceptable materials includes both asphalt shingle and metal. So Class 4 is available in either material, and the rating is what matters, not the material category.
The IIBEC study raises a caution worth carrying into a sales conversation: it recommends that “metal roofing manufacturers should provide consumers with test data documenting FM and UL compliance,” and that pass/fail criteria should be better defined. Ask for the test documentation for the specific product being quoted rather than accepting a general claim that metal is hail resistant.
Is a metal roof noisier?
The concern comes from experience with uninsulated shops and barns, where a bare panel sits on purlins with open air underneath.
A residential metal roof is a different assembly: panel over underlayment over solid sheathing, above an insulated attic. That stack absorbs most of the impact sound. In normal rain, a metal roof over a finished attic is not meaningfully louder than asphalt. Heavy hail is audible on any roof.
Where it can matter is over a cathedral ceiling or a low-slope section with minimal attic space above a bedroom. Natural Resources Canada notes in its guidance on roofs and attics that houses with flat roofs, cathedral ceilings, or attic-less construction are “difficult and will require the services of a qualified contractor” because of the limited space for insulation and ventilation. If that describes part of your house, raise sound and insulation together with your contractor before the panel goes on.
Does the roof material affect heating costs?
Less than the attic underneath it does, which is the part most homeowners get backwards.
Natural Resources Canada’s “Keeping the Heat In” guide is direct that air sealing is the priority: “Air leaks into the attic can account for substantial heat loss and can lead to a variety of moisture-related problems. The importance of air sealing cannot be overstated.” The guide also notes that relatively easy access makes the attic a favourite starting point for homeowners, “despite the fact that most other areas, such as basements and uninsulated walls, lose more heat than the typical attic.”
The practical implication for a roof replacement is that neither metal nor asphalt will fix a leaky ceiling plane. What a re-roof does is give you access at the moment when adding insulation, correcting ventilation, and addressing ice dam conditions is cheapest.
NRCan cautions about ventilation specifically: ensure the contractor prevents insulation from entering the eaves and blocking ventilation, take precautions around recessed light fixtures and chimneys in the attic to avoid a fire hazard, and where the roof extends past the exterior walls, consider soffit vents combined with roof or ridge vents. It also suggests checking the roof space during or just after a midwinter cold snap: some frost is expected, but heavy buildup means you need to vent the space, seal air leaks, and reduce indoor humidity.
What about snow shedding?
Metal sheds snow in sheets rather than melting it off gradually. That reduces accumulated load, which is an advantage, but it creates a hazard over doorways, walkways, and driveways.
Snow guards installed above entries and high-traffic areas solve this, and they need to be planned as part of the design rather than added after the first release. This is a real difference from asphalt, which holds snow until it melts.
Which should you choose?
Choose metal if you plan to stay in the house long enough for the service life to pay back the higher up-front cost, if you are in an active hail corridor and can accept that dents are cosmetic, and if your roof geometry suits long panel runs.
Choose asphalt if the up-front cost is the constraint, if you expect to sell within a few years, or if neighbourhood consistency matters to you. If you choose asphalt in Alberta, choose an impact-resistant Class 4 product. The Calgary rebate exists precisely because upgrading the asphalt rating is the highest-value change most homeowners can make.
In both cases, the failure points are the same and they are not the field of the roof. They are the flashing at valleys, chimneys, sidewalls, and penetrations, the condition of the deck underneath, and whether the attic below is sealed and ventilated properly.
Frequently asked questions
Will a metal roof dent from hail? Yes. Laboratory testing produced indentations in all metal roofing tested, with depth varying by gauge, profile, and metal type. Field investigations after major hail events found those dents to be cosmetic, with no functional damage to the coating or plating and no evidence of leakage.
Does a dented metal roof leak or rust? The 50-year field record reported in the IIBEC study found no long-term corrosion or deterioration at hail impact points, and concluded that minor dents have no effect on long-term performance. Leakage required dents large enough to distort side or end laps, which takes exceptionally large hail.
How long does a metal roof last? The Metal Construction Association field study projects in excess of 60 years for a properly installed standing seam system, with the butyl sealant at laps and joints, rather than the metal, determining end of life.
Can I get a Calgary rebate for a metal roof? Metal is on the City of Calgary’s list of acceptable materials for the Resilient Roofing Rebate, provided the specific system carries a Class 4 rating under UL 2218 or FM 4473 and the installation meets the program checklist. Confirm program availability before starting work.
Is standing seam better than exposed fastener metal? For a house, generally yes. Standing seam hides the fasteners under the seam, removing the most common long-term leak point, and lets panels move with temperature. Exposed fastener systems are more common on shops and outbuildings.
Does a metal roof help with heating costs? Not directly. Natural Resources Canada identifies air leakage into the attic as the significant heat loss path, not the roof covering. The value of a re-roof for energy performance comes from air sealing and insulating while access is open.
Will a metal roof interfere with satellite or cell reception? This is a common concern with no meaningful basis for residential installations. Antennas and dishes are mounted above the roof surface.
Sources
- Metal Construction Association, “Service Life Assessment of Low-Slope Metal Roof Systems” (white paper, 2018): https://metalconstruction.org/index.php/online-education/service-life-assessment-of-low-slope-unpainted-55-al-zn-alloy-coated-steel-standing-seam-metal-roof-systems—published-102018
- Koontz J.D., White T.L., “The Effects of Hail on Metal Roofing Systems,” 29th RCI International Convention and Trade Show (2014): https://iibec.org/wp-content/uploads/2014-CTS-koontz-white.pdf
- Natural Resources Canada, “Keeping the Heat In,” Section 5: Roofs and attics: https://natural-resources.canada.ca/sites/www.nrcan.gc.ca/files/energy/pdf/housing/Chapter5_e.pdf
- City of Calgary, Resilient Roofing and Hail: https://www.calgary.ca/content/dam/www/pda/pd/documents/hail-roofing-rebate/Resilient-Roofing-and-Hail-Brochure.pdf