The number on the shingle bundle is not the number you will get. Toronto's winters are hard on roofs, and how long yours lasts depends as much on how it was installed, and on what is happening in the attic below it, as on the material itself.
The short answer
| Roof | Typical life in Toronto |
|---|---|
| Architectural asphalt shingle | About 20 years |
| Three-tab asphalt shingle | 15 to 20 years |
| Two-ply modified bitumen (flat) | 20 to 30 years |
| Cedar shake, ventilated batten system | 30 to 50 years |
| Cedar shake, laid flat on felt | 15 to 25 years |
| Standing-seam steel, PVDF (Kynar 500) finish | 50 to 70 years |
| Copper or zinc | 80 to 100 years or more |
These assume a roof installed properly, over a ventilated attic, and looked after. A poorly installed roof of any material can fail in a third of that time.
Why the package says fifty years
Many architectural shingles are sold with a 30-year, 50-year or "lifetime" warranty. That is a prorated material warranty, not a promise of service life. It covers manufacturing defects in the shingle, its value drops steeply after the first years, and it does not cover the installation or the weather. In Toronto's freeze-thaw climate, about twenty years of trouble-free service is what an architectural shingle roof honestly gives you. We explain more on our shingle roofing page.
What shortens a roof's life here
- Freeze-thaw cycling. Toronto crosses 0 °C on roughly seventy days a year. Water that gets into a joint freezes, expands and pries it open a little further each time.
- Ice dams. Heat escaping into the attic melts snow from below, and the meltwater refreezes at the eaves and backs up under the roof. See why Toronto homes get ice dams.
- A hot attic. Poor ventilation bakes shingles from underneath in summer and feeds ice dams in winter. Our attic ventilation guide covers what good looks like.
- Sun on south and west slopes. UV breaks down asphalt fastest on the slopes that face it, which is why one side of a roof often wears out first.
- Trees. Shade keeps a roof damp, debris blocks valleys and eavestroughs, and moss lifts shingles.
- Flashing. Chimneys, skylights, valleys and walls are where most leaks start. Old flashing reused under new shingles is a common reason a "new" roof leaks early.
Signs your roof is near the end
- Shingle granules collecting in the eavestroughs or at the bottom of downpipes
- Shingles curling at the edges or cupping in the middle
- Cracked, torn or missing shingles after ordinary wind
- Bald or dark patches where the granules have gone
- Water stains on upstairs ceilings, or daylight visible from inside the attic
- A deck that dips or feels soft between the rafters
- Moss or lichen spreading across a slope
One of these on its own often means a repair. Several together on a roof approaching twenty years usually means it is time to plan a replacement.
How to make a roof last longer
- Have it looked at twice a year, once after the thaw and once before the snow. Our Toronto roof calendar lists what to check each season.
- Keep the eavestroughs and valleys clear, so water leaves the roof instead of sitting on it.
- Fix the attic: air sealing, insulation and balanced ventilation do more for a roof's life than anything you can do on top of it.
- Deal with flashing early. A small repair at a chimney is cheap. Rotted sheathing under it is not.
- Never pressure-wash shingles or chip ice off a roof. Both strip the surface that protects it.
Repair or replace?
If the roof is under about fifteen years old and the damage is in one place, repair it. If the wear is spread across the roof and it is approaching twenty, a replacement is usually better value than chasing leaks one by one. For a sense of what replacement costs, see roof replacement costs in Toronto.
Not sure which one you are looking at? We will inspect the roof and the attic, and tell you honestly, even if the answer is that it has years left.