How to tell a roof is past repairing

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.

Daylight or damp in the attic

The attic tells the truth earlier than the ceiling does. Staining on the underside of the deck predates any stain you will see downstairs by a long way.

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.

The age on the paperwork

If the roof is over twenty years old and made of asphalt, an inspection is worth doing whether or not it is leaking. The failure modes above are much cheaper to catch before the water arrives than after.

Sagging along a line

A ridge or a plane that dips is a structural signal rather than a covering one. It usually means decking that has been wet long enough to lose strength, and occasionally framing. This is the one symptom that should not wait.

Repeated repairs in different places

One leak is an event. Three leaks in three different areas inside two years is a pattern, and the pattern means the covering has reached the end of its service life rather than suffered a specific failure.

In short

None of these on their own settles it. Two together usually do. An inspection costs little and removes the guesswork entirely.