When patching stops being worth it

Daylight or damp in the attic

Go up on a bright day with the lights off. Pinpoints of daylight through the deck, dark staining on the sheathing, damp insulation or rust running down a nail shank all say water is getting in and has been for a while.

Shingles that curl, cup or go brittle

Look along the roof from the ground at a low angle rather than straight on. Edges that lift, corners that curl upward and a surface that no longer lies flat all mean the material has lost its flexibility. Brittle shingles crack when walked on, which is why contractors stop wanting to walk them.

Sagging along a line

Straight lines going wavy means something underneath has softened. That is no longer a roofing question with a cheap answer.

Repeated repairs in different places

When the leaks stop clustering and start appearing anywhere, you are not fixing a fault any more. You are paying for a replacement in instalments, at a worse rate.

Granules in the gutter

Asphalt shingles are protected by a granular surface. When that surface starts washing off in quantity, the mat underneath is exposed to ultraviolet and the clock speeds up sharply. A handful of granules after a new roof is normal shedding. Cupfuls, years later, is not.

The age on the paperwork

Age alone is not a reason to replace. Age plus any one of the symptoms above usually is.

In short

If two or more of these apply, get somebody to look at it and give you a remaining-life number in years. That single number turns the decision from a worry into arithmetic.