Why do chimney leaks keep coming back after patching?
Because the patch addresses the symptom. Roofing cement over rusted flashing, or caulk over a cracked crown, does not rebuild the joint. Chimneys move, and the sealant breaks again. Lasting repairs replace the flashing, set the counterflashing into the masonry, and fix the masonry above it.
A chimney leak can come from several levels at once. A roofer may fix the flashing and find water still entering from the crown above it.
That is why a thorough look matters. Ask the roofer to check from the roof, not only from a ladder.
Is it a roofer's job or a mason's?
Both, in different places. The roofer owns the flashing, shingles and cricket where the chimney meets the roof. A mason owns the brick, mortar, crown and flue. Many leaks involve both, and the roofer should tell you which parts belong to which trade, and coordinate them if you want.
Ask for the work to be sequenced. Masonry repair should come before the flashing is reset, since the counterflashing sits in the mortar.
Do not accept a single quote that blurs the two trades.
Do I need to check my chimney if it is not leaking?
A look every few years is sensible, particularly on older houses. Mortar and crowns wear slowly and the damage is hidden until a leak starts. A pre-winter check from the roof can catch gaps in flashing and cracks in masonry while they are small and cheap to fix.
The page on roof inspection describes what a roofer checks. Chimneys are on the list.
What if the chimney is old and fragile?
A deteriorating chimney can be unsafe, and work on it should be planned. Leaning, large cracks, loose bricks or a tilt are reasons to stay away and call for professionals at once. A roofer will not stand on or lean ladders against a chimney that may give way.
A chimney that is no longer used can sometimes be capped and roofed over, a decision for the owner, a roofer and often the town building office.
What should I do about a chimney before winter?
Have the flashing, crown and mortar joints looked at in autumn, clear leaves from the roof around the base, and trim limbs that scrape. Early attention costs less than a leak in February, when ice and snow load stress every joint and a crew may not be able to climb.
Autumn is the best time because the roof is dry and the roofer can see the whole joint. Winter repairs are possible but are limited by ice and cold, and sealants do not bond well in low temperatures.
If the chimney is used, have the flue cleaned and checked by the proper trade. A roofer does not replace that inspection, and a chimney sweep does not replace a look at the flashing.
