What to do, and when

Keep the penetrations honest

Rubber pipe boots are the single most common source of leaks on an otherwise sound roof, and they are cheap to replace before they fail.

Look in the attic after heavy weather

Check after the first real weather of the season rather than at the end of it. A small stain found in autumn is a cheap repair; the same stain found in spring is not.

Twice a year, from the ground

You do not need to be on the roof to find most problems. A slow lap of the house at a low angle finds nearly all of them.

Clear the gutters before the wet season

Blocked gutters back water up under the bottom course of shingles and rot the fascia behind them. This is the highest-value hour of maintenance there is, and here it wants doing before November through March.

Deal with growth properly

Cleaning a roof aggressively does more damage than the growth was doing. Gentle treatment, patience, and a strip at the ridge to stop it returning.

Cut back anything touching the roof

Overhanging limbs cause three problems at once: abrasion, permanent shade that keeps a slope damp, and a highway for rodents into the attic.

In short

None of this is difficult and none of it is expensive. It is simply the difference between a roof that reaches its rated life and one that does not.