British Columbia · Roof lifespan guide
How long does a metal roof last in BC?
It depends on the metal, the coating, the fasteners and the installation. Steel lasts about as long as its coating keeps it from rusting. Aluminum doesn't rust, and aluminum has been known to last over 100 years. That is a property of the metal, not a promise; what we and the manufacturer promise is in the warranties, set out below.
Reviewed by Scott Plumptree, Director of Marketing, The Interlock Group · Updated October 8, 2026
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The metal
Aluminum has been known to last over 100 years
Aluminum doesn't rust. A property of the metal, not a promise.
The material
Guardian Lifetime Limited Material Warranty
Material and finish, for the original purchaser's ownership. Transferable once.
The finish
30 Year Alunar® Coating Warranty
On the paint finish that carries the colour.
What decides how long a metal roof lasts
"Metal roof" covers very different products. Four things decide how long one lasts on your house.
The metal
Steel rusts wherever its protective coating is scratched, cut or worn through, so a steel roof lasts about as long as its coating. Aluminum doesn't rust. It forms a thin oxide layer on its own surface, which is why aluminum has been known to last over 100 years.
The coating
The paint finish decides how the colour holds up to sun and weather. Interlock® roofs carry a 30 Year Alunar® Coating Warranty on the finish, separate from the material warranty.
The fasteners
Exposed screws through the weather surface rely on rubber gaskets that age in sun, rain and cold. Interlock® panels lock to each other on all four sides with the fasteners concealed, so there is no exposed screw head for water or wind to work on.
The installation
Flashing at walls, chimneys, valleys and skylights, the underlayment, the ventilation of the attic below, and the slope (every Interlock profile needs a minimum 3/12) decide how a roof performs for decades. Wind resistance is warranted to 193 km/h (120 mph) installed to manufacturer specification.
What the weather in BC does to a roof
Wet coastal winters
From Metro Vancouver to the Island and the Sunshine Coast, a roof spends most of the winter wet. Cedar holds that water and softens; asphalt granules trap the debris moss grows in. Aluminum absorbs nothing and cannot rot. Valleys and gutters still collect needles and leaves, so we'll tell you what to clear and how often.
Salt air on the coast and islands
Waterfront homes on the coast, the Island and the Gulf Islands take salt spray all year. Aluminum does not rust, so salt air doesn't do to it what it does to steel.
Okanagan and Thompson summers
The Interior's summers are hot and dry, with long fire seasons. Class A is available on our roofs as a complete assembly (two layers of GAF VersaShield® over 12 mm (15/32-inch) plywood, per ASTM E108), and aluminum does not ignite. FireSmart BC calls the house and the first 1.5 m around it the most critical zone, because that is where embers reach the roof, gutters and vents.
Interior and mountain snow
Sea-to-Sky, the Interior and the upland slopes get real snow. A metal roof sheds it, so snow guards over entries, decks and driveways go in at the estimate, and the light panels leave the framing's capacity for the snow load the BC Building Code sets for the location.
Interlock® roofs in BC
Recent Interlock® roofs installed by our own BC company. Tap a roof to see all of its photos.
Metal, asphalt and cedar compared
Published life expectancies are averages. Local weather, the building and its design, material quality and maintenance all move them, as the study below says itself.
| Roof | Life expectancy | Basis | What to know |
|---|---|---|---|
| Asphalt shingles | About 20 years | NAHB / Bank of America study (2007) | When it is done, it comes off or, if suitable, is roofed over once. |
| Wood shakes | About 30 years | NAHB / Bank of America study (2007) | Holds water through a wet winter, grows moss, splits and rots as it ages. Always torn off before a new roof. |
| Interlock® aluminum | Aluminum has been known to last over 100 years | A property of the metal, not a promise | What is in writing: the Guardian Lifetime Limited Material Warranty and the 30 Year Alunar® Coating Warranty. |
Asphalt and wood shake figures: National Association of Home Builders and Bank of America Home Equity, Study of Life Expectancy of Home Components, February 2007 (a US study). Full reference at the end of this page.
The warranties, stated separately
How long aluminum can last and what is in writing are two different things. Here is what is in writing on an Interlock® roof installed in BC.
- Guardian Lifetime Limited Material Warranty, from the manufacturer, Interlock Roofing: material and finish, for as long as the original purchaser owns the home, transferable once. Workmanship is excluded, and ice damming is a stated exclusion.
- 30 Year Alunar® Coating Warranty on the finish.
- 10 Year Limited Labour Warranty from Interlock Metal Roofing (BC) Ltd., covering our installation.
- Wind resistance warranted to 193 km/h (120 mph) installed to manufacturer specification.
Questions, answered
How long does a metal roof last?
It depends on the metal, the coating, the fasteners and the installation. Steel lasts about as long as its protective coating, because it rusts where the coating fails. Aluminum doesn't rust, and aluminum has been known to last over 100 years. That is a property of the metal, not a promise; what is promised is in the written warranty.
How long do metal roofs last in BC?
Wet winters, moss, salt air, summer heat and snow are hard on roofing that absorbs water or relies on exposed screws. An aluminum roof with concealed fasteners, installed to manufacturer specification with good attic ventilation, avoids the usual failure points. Its material and finish are covered by the Guardian Lifetime Limited Material Warranty and the 30 Year Alunar® Coating Warranty.
Does a metal roof last longer than asphalt or cedar?
In published figures, yes. A 2007 study by the US National Association of Home Builders and Bank of America put the life expectancy of asphalt shingles at about 20 years and wood shakes at about 30, noting that local weather, building and design, material quality and maintenance all affect it. Aluminum has been known to last over 100 years.
How long does a steel roof last?
A steel roof lasts about as long as its metallic coating and paint keep water off the steel; where the coating is scratched or cut, steel rusts. We install aluminum, which doesn't rust.
Will the colour fade?
All exterior finishes change with years of sun. The Alunar® finish on Interlock® roofs carries a 30 Year Alunar® Coating Warranty; the terms set out what is covered.
What maintenance does a metal roof need?
Keep gutters and valleys clear of needles and leaves, look the roof over after a major storm, and keep attic vents open. With concealed fasteners there are no exposed screws to re-tighten or re-seal.
Sources
- National Association of Home Builders / Bank of America Home Equity: Study of Life Expectancy of Home Components (February 2007)
- Guardian Lifetime Limited Material Warranty (full terms)
- 10 Year Limited Labour Warranty (BC)
- Interlock Roofing: the aluminum roofing system
Product specifications are the manufacturer's (Interlock Roofing). Install counts are from our own job book. Reviewed by Scott Plumptree, October 8, 2026.
Get an aluminum roof priced.
A fixed price in writing after one visit, on Zoom or at your home. Most BC homeowners choose Zoom. Interlock Metal Roofing (BC) Ltd. · 9969 River Way, Delta, BC V4G 1M8
