There's no single rule, but a few questions point you in the right direction.
How old is the roof?
Asphalt shingle roofs are commonly rated for around 20 to 30 years, depending on the product. A roof near the end of that range is often a better candidate for replacement than for another repair.
How much of the roof is damaged?
Damage in one spot, like a few missing shingles or one bad vent boot, is usually a repair. Damage spread across most of the roof, like hail hits on every slope, points toward replacement.
Is insurance involved?
If a covered storm damaged the roof, your policy may pay for repair or replacement, minus your deductible. Wear and age usually aren't covered. Read our insurance guide.
How long are you staying in the house?
If you're selling soon, a solid repair plus an inspection report may be enough. If you're staying for years, a new roof can save you repeated repair bills. Our guide to what affects replacement cost helps you read the quotes.
A roofer can look at your roof and walk you through both options. Request a callback.