Everybody wants a number. The number is the least useful thing anyone can give you.
Two houses on the same street in Woodstock, same builder, same year, same shingle off the same pallet. One is sound at twenty-two years and one was finished at fourteen. Nothing about the product explains that.
What explains it is what happened underneath, and how much snow sat on top.
A warranty is not a service life
The two get conflated constantly, and the difference costs people money.
A shingle warranty is a document about manufacturing defects. It usually runs at full coverage for an early period and then prorates away over the remaining term. It is generally conditional on the shingle having been installed in conformance with the manufacturer’s written instructions — which the Ontario Building Code also requires, in the article that governs installation of roofing materials.
What sits outside it is nearly everything that actually ends roofs: workmanship, ventilation, ice damming, wind, and a deck that was already soft when the last crew went over it.
So what does a warranty term tell you?
That the manufacturer is confident the mat and the granules will survive that long in a laboratory sense. Treat it as a specification of the product you are buying, worth comparing between products, and worth nothing at all as a prediction about your house.
What actually ends an asphalt roof
Four failures, in roughly the order you will meet them.
| Failure | What you see | What it means |
|---|---|---|
| Granule loss | Grit in the eavestrough, dark patches | The mat is losing its sunscreen |
| Sealing strip failure | Tabs lifting in ordinary wind | The roof no longer works as one surface |
| Mat degradation | Curling, cupping, brittleness | Finished, regardless of age |
| Deck damage | Sag, springiness underfoot | Structural, and invisible until tear-off |
Granules are the clock
Granules are the shingle’s protection from ultraviolet light. Losing them is normal and slow at first, and a handful in the eavestrough after a new roof is factory surplus rather than a symptom.
A steady accumulation years later is different. Once the mat is exposed it degrades quickly, and the roof stops being a maintenance question.
Why do the south and west slopes always go first?
More sun and more of the weather. On a house in Leamington or Chatham on the Erie shore, the west face takes both the ultraviolet load and the storm wind off flat farmland with nothing upwind to slow it. Slopes ageing at visibly different rates on the same roof is normal, and it is the one case where replacing a single slope is a genuine option rather than a shortcut.
The sealing strip is the quiet one
Every asphalt shingle has an adhesive strip that bonds it to the course below. That bond is what makes a roof one continuous surface instead of several thousand loose tiles, and it is what resists uplift in wind.
When those strips let go, the roof looks completely normal from the ground and behaves like a much older one in a storm. It is the usual explanation for a roof that loses tabs in a wind nobody would describe as severe.
Why the town changes the answer
This service area runs from Lake Huron down to Lake Erie, and the weather at the two ends is not the same weather.
The snowbelt end. Stratford averages about 218 cm of snow a year, Listowel about 192 cm, Strathroy about 170 cm, and the country inland of Goderich more again off Lake Huron. Snow that sits for weeks rather than days is what drives the ice dam cycle, and an ice dam is a heat problem rather than a roof problem — but the roof is what wears out paying for it.
The Erie shore end. Chatham averages about 79 cm and Leamington about 86 cm. Snow rarely stays long enough for a dam to build, which removes that failure mode entirely. What replaces it is wind and sun on a roof with no shelter upwind.
Freeze-thaw cycling works on both ends. The corridor runs roughly 94 to 107 freeze-thaw days a year, and every one of them works a lap, a seam and a flashing joint.
When repair stops being the cheaper answer
There is a real line here and it is not about age.
Repair is right when there is one identifiable cause on a roof that is otherwise sound. A split stack boot is the single most common roof leak we spot and it is a cheap fix at any age. Step flashing behind an addition, a lifted ridge cap, a nail pop — all repairs, all worth doing.
Replacement is right when the roof has multiple unrelated failures at once, when the granule loss is general rather than local, or when the deck has been wet. Three leaks since spring is not three repairs. It is a roof telling you something.
The inspection with written findings is what separates the two, and it costs a fraction of guessing wrong in either direction. The cost of a replacement here is worth knowing before you need to decide, not after.
What we will tell you not to spend money on
A replacement because the roof hit a birthday. Age is one input. A sound twenty-two-year-old roof with tight sealing strips and a dry deck owes you nothing yet.
A fourth repair on a roof with three failures. That money is gone and it does not come off the replacement.
An inspection you cannot keep. If it ends in a verbal opinion and a price, it was a sales call. Ours ends in a document with photographs, and you are welcome to take it to somebody else.