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Roof Repair or Replacement: The Attic Tells You, Not the Shingles
Roofing
Repair the Roof or Replace It?
A roofer who sells roofs will tell you it needs replacing. A handyman who patches roofs will tell you it needs patching. Both of them are standing on your driveway looking up at shingles, and the shingles are the last thing to look at. The roof’s age, what the attic looks like from underneath, and how many places it has leaked are the three things that decide this, and you can check all three before anyone comes out.
The three questions
- How old is it? Architectural shingles in Ontario give 22 to 30 years; 3-tab, 15 to 20; the cheap builder shingle on a 2005 subdivision house, closer to 18. Under 15 years and a leak is a defect to repair. Over 22 and a leak is the roof telling you something. Do not know the age? The next section.
- What does the attic look like? Go up with a flashlight on a bright day and look for daylight at the roof edges and around the chimney, dark stains on the underside of the sheathing, nails with frost or rust rings around them, insulation that is damp or matted, and plywood that has delaminated into layers. Stains in one place are a flashing leak. Stains everywhere are a roof that has been letting water in for years, and that deck is now part of the bill.
- How many places has it leaked? One leak, at a chimney or a vent, is a repair. A second leak in a different place within two years means the shingles have lost their seal, and chasing them one at a time costs more than a roof.
How to find out how old the roof is
Your purchase documents or the previous owner’s disclosure, if any. The building department sometimes has a record if a permit was pulled, which for a re-roof it usually was not. The shingle manufacturer’s date code is printed on the underside of the shingles, which you can read from a torn one or from the attic side at a soffit. Failing those, look at it: a roof with the tabs curling at the corners, with black patches where the granules have gone, and with eavestroughs full of what looks like coarse sand, is over 20 whatever the paper says.
Repair costs, by the job
| Repair | Ontario, 2026 | Notes |
|---|---|---|
| Service call and leak finding | $250 to $450 | Credited against the repair by most roofers |
| Replace a dozen blown-off or damaged shingles | $350 to $900 | Colour will not match on a roof over 5 years old |
| New pipe boot or vent flashing | $250 to $500 | The most common leak on a roof under 15 |
| Chimney re-flash, step and counter flashing | $800 to $2,000 | Plus repointing if the brick is soft |
| Rebuild a valley | $1,000 to $2,500 | Shingles out, ice and water in, metal valley, shingles back |
| Skylight re-flash | $500 to $900 | If the skylight itself is fogged, replace it: $1,200 to $2,500 |
| Emergency tarp | $300 to $700 | Buys a week, not a season |
| Ice dam steaming | $400 to $1,200 | Removes the dam, fixes nothing |
| Replace a few sheets of rotten deck under a repair | $120 per sheet plus the shingles over it | Found when the shingles come off |
The rest of the repair side, including how to find the leak before the roofer comes, is on roof repair cost and roof leak diagnosis.
When repair is good money
- Roof under 15 years, one leak, at a flashing, a boot, a skylight or a valley. Fix the thing that failed.
- Wind took a patch of shingles off an otherwise sound roof. Patch it, accept the colour.
- A tree branch punched a hole. Insurance repair, patch and move on.
- You are selling in the next year and the roof has 5 years left. A repair plus a disclosure beats a $15,000 roof the buyer does not pay you for.
- The roof is 20 but the attic is dry and bright, the shingles are flat, and the leak is at the chimney. Re-flash the chimney and plan the roof for year 25.
When repair is money thrown off the roof
- Over 22 years and curling. The seal strips have let go; every wind finds a new tab.
- Granules in the eavestroughs by the handful. The asphalt underneath is now in the sun, and it goes fast from here.
- A second leak in a different place inside two years.
- Stains across the attic sheathing, not in one spot. The deck has been wet for years and it is part of the next roof.
- A sag in the ridge or a dip in a plane. Not a roofing problem; a framing or deck problem under the roofing, and the roof comes off to fix it.
- The roofer wants $4,000 to patch a roof that is $14,000 to replace. Past about a quarter of the replacement cost, repairs on an old roof are a down payment on nothing.
The five-year rule
If the roof has fewer than five years left by age and condition, do not spend repair money on it beyond a tarp and a boot; put the money toward the replacement and book it for the shoulder season when it is cheaper. If it has more than ten years left, repair without a second thought. In between, let the attic decide: dry deck, repair; stained deck, replace. And get the second opinion from someone who does not sell roofs, which is roughly what the $99 quote review is for, with photos of the attic and the roof.
Questions people ask
How do I know if my roof needs to be replaced?
Age over 22 years, shingles curling or bald, granules in the eavestroughs, stains across the attic sheathing, or two leaks in different places. Any two of those and it is a replacement. One flashing leak on a 12-year-old roof is a repair.
Can I replace just part of a roof?
A single plane or a section, yes, and it is done on additions and after storm damage. The new section will not match the old in colour and the seam between them is a weak point unless it lands at a ridge or a valley. Sensible for a five-year bridge; not a long-term plan.
How long will a repair last?
A new flashing or boot on a sound roof lasts as long as the roof. A patch of shingles on an old roof lasts until the shingles around it let go, which on a 22-year-old roof is the next big wind.
Is a leaking roof an emergency?
A roof leaking into the house is a tarp today and a decision this week. Water that has been coming in for a season has already wet the insulation and the drywall, and the mould conversation starts at about 48 hours. Stop the water first, decide second.
Should I replace the roof before selling?
If it is due, yes, because the buyer’s inspector will find it and the price reduction they ask for is more than the roof. If it has five good years, disclose the age and leave it.
Go and look at the attic
Flashlight, bright day, ten minutes. Dry and bright means repair. Stained and dark means price the roof. Nobody standing on your driveway can tell you what you will see up there.
Sources and further reading
- Ontario’s Building Code: the official page, with the current regulation (O. Reg. 163/24). Roofing is Section 9.26, attic ventilation 9.19.
- Keeping the Heat In, Chapter 5: Roofs and attics: Natural Resources Canada. The best free guide to attic insulation, air sealing and ventilation written for Canadian houses.
- Your rights when starting home renovations or repairs: Ontario government. The 10-day cooling-off period, the 10% estimate rule, and what a contract has to say.
