Almost everyone who calls about a leak expects to be told they need a new roof. Most of them do not. The decision comes down to three things, and you can check two of them from the ground.
The first is age against expected life. Asphalt shingle runs fifteen to thirty years depending on grade. If your roof is eight years old and leaking, something has failed — a boot, a flashing, a nail pop — and that is a repair. If it is twenty-six years old and leaking, the material has reached the end of its life, and patching it buys you a season at most.
The second is how much of the roof is involved. One leak with one source is a repair. Water showing up in three unrelated places usually means the underlayment has gone, and underlayment cannot be replaced without taking the covering off.
The third is the deck, and this is the one you cannot check yourself. If the sheathing under the covering has been wet for years it will be soft, and a roof laid over soft decking will fail early no matter how good the shingle is. That is why a proper inspection lifts something rather than looking from a ladder.
A reasonable roofer will tell you when a repair is the right call, because the alternative is selling somebody a roof they did not need and losing every referral they might have made. If a contractor goes straight to replacement without opening anything up, get a second opinion.
