Chimney Flashing Repair in Connecticut

A chimney is masonry sitting on the ground; a roof is timber that moves with temperature and load. Where the two meet there is a gap that has to be sealed and has to tolerate movement, and flashing is what does it.

Done properly it is two layers. Step flashing runs up the sides in pieces, woven in with the shingle courses. Counter flashing is let into a mortar joint in the brickwork and folded down over the step flashing, so water running down the stack is directed out onto the roof rather than behind it.

Failure comes from movement, corrosion, or a shortcut at the original installation — most commonly counter flashing surface-mounted and sealed rather than let into the masonry. Sealant has a life measured in a few years outdoors; a properly let-in flashing has a life measured in decades.

The failed metal comes off, along with whatever sealant or tar has been applied over it. New step flashing is woven in with the shingle courses up both sides, and new counter flashing is cut into a mortar joint in the brickwork and folded down over it.

The joint is then pointed and sealed — but as the last step rather than as the repair itself. The distinction matters: flashing that works does so because of how the metal is layered, not because of what has been smeared over the top of it.

Where the masonry itself has deteriorated at the roof joint, that gets addressed first. There is no point letting counter flashing into mortar that is failing.