Can I fix a roof leak myself?

What is worth doing yourself

Move furniture and anything valuable out from under it, because water spreads along a ceiling before it comes through. Put a container under an active drip. If a ceiling is bulging with trapped water, a small hole at the lowest point drains it in a controlled way rather than letting the whole thing come down at once.

Photograph everything, inside and out, before anything is cleaned up — that is what an adjuster will want. And if water is anywhere near a light fitting or an outlet, turn off the circuit before you go in.

What we would leave alone

The roof itself, particularly in the weather that caused the leak. Most of the serious injuries in this trade happen on wet or storm-damaged roofs, often to people who were trying to save a few hundred dollars. It is not a proportionate risk.

Also the tempting bit: running a bead of sealant over the suspect junction. Sealant has a service life of a few years at best, and correctly installed flashing does not depend on it. A sealed junction usually means the same leak returns, except now the original cause is buried under caulk and harder to diagnose.

The genuinely DIY-able repairs

If you are comfortable on a roof in dry conditions and the cause is obvious, replacing a perished vent boot or a single lifted shingle is within reach for a competent DIYer.

Flashing is not, and that is not gatekeeping — step flashing has to be woven into the shingle courses and counter flashing set into masonry, and a strip of metal bent over the junction instead will leak. Valleys are the same. Those are the causes that matter most and they are the ones that need doing properly.