A roof repair is usually $400 to $1,500. A replacement is usually $7,000 to $15,000. The gap is wide enough that repair looks right almost every time, and that is exactly why so many roofs get repaired three times before they get replaced.
Four tests decide it, and one of them settles the question on its own.
Test 1 — Age against expected life
| Shingle type | Expected life | Repair still sensible until |
|---|---|---|
| Three-tab | 15–20 yr | ~12 yr |
| Architectural | 22–30 yr | ~18 yr |
| Impact-rated | 25–30 yr | ~20 yr |
Past roughly 75% of expected life, a repair is buying a year or two on a roof that will need replacing regardless — and material choice sets that expected life — and it is being installed by someone who will not warranty the rest of the roof.
If you do not know the age, the sale record for the house usually does, and so does the local permit office.
Test 2 — Extent
The rule of thumb crews use: under 30% of one roof plane, repair; over that, replace the plane or the roof.
Below 30%, a competent repair blends in and lasts. Above it, you are patching so much area that matching becomes visible and the untouched parts are the same age as the parts that failed.
Matching is a real constraint. Shingle colours are discontinued and asphalt fades. A repair on a ten-year-old roof will not match, and on a front elevation that matters to some people and not to others. Ask for the offcuts to be kept from any repair — they are the only true colour reference you will ever have.
Test 3 — Deck condition
This is the one that overrides everything else.
Signs the deck is compromised: a sag along the ridge or between rafters, a soft or spongy feel underfoot, staining or daylight visible in the attic, or nails backing out in numbers across a whole plane.
Any of these means the problem is under the shingles, and shingles are not the repair. A roof with a wet deck gets torn off, whatever its age — because the alternative is sealing moisture into the structure.
Check the attic on a bright day with the lights off. Daylight through the deck is unambiguous. So is a musty smell in a space that should smell of dust.
Test 4 — Layer count
Two layers already means the next roof is a tear-off, full stop. It also means any repair is being nailed through two layers into a deck nobody can see, which is a repair with a guess inside it.
Lift a shingle at the rake edge, or look at the roof edge from a ladder. The layer count is visible from the side.
The specific failures worth repairing
Some problems are genuinely local and worth fixing on a roof that otherwise has life left:
- Wind-lifted tabs in one area after a storm
- A single damaged plane from a fallen limb
- Flashing failure at a chimney, wall or vent stack — this is the most common leak source on roofs of any age, and it is a repair, not a roof
- Cracked pipe boots — the rubber collar around a plumbing vent perishes long before the shingles do, and it is a $150 fix that people replace whole roofs over
That last one is worth checking before anything else. Stand in the attic under each vent stack after rain. If the leak is there and only there, the roof is fine.
The failures that mean replacement
- Granule loss across whole planes — check the gutters; if they are full of granules, the shingles are giving up their surface
- Curling or cupping across the field rather than in patches
- Multiple leaks in different places — one leak is a detail, three are a system
- Bald spots where the fiberglass mat is visible
The honest arithmetic
A $1,000 repair on a roof with three years left is $333 per year. A $10,000 replacement with 25 years is $400 per year. Those are close enough that the repair wins on a dry roof.
The same $1,000 repair on a roof that leaks again next winter, and again the year after, is $3,000 spent to arrive at the replacement anyway — with two winters of water in the structure.
The question is not "can this be repaired". Nearly anything can be repaired. It is how many more times.
If the answer is once, repair. If it is three, the money is better spent on the roof you were going to buy regardless — and the installed cost per square is the number to start from.