Fix it
Why is my roof leaking around the chimney?
The chimney is the biggest hole anyone ever cut in your roof, and the metal flashing sealing that joint fails more often than any equivalent area of shingle. Stains on the ceiling near the chimney chase are its signature.
What it usually is
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Step and counter flashing pulling apart
The two-layer flashing system around a chimney relies on overlap. Mortar joints holding the counter flashing loosen, the metal lifts, and wind-driven rain gets behind it.
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Dried-out sealant at the flashing edges
Caulk-sealed flashing has a service life of a decade at most. Once it shrinks, every rain deposits a little water into the chase.
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A cracked chimney crown or cap letting water in from the top
Water entering through the crown runs down inside the chase and appears at the ceiling as if the flashing failed. Efflorescence — white staining on the brick — is the tell.
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Missing cricket on a wide chimney
Chimneys wider than about 30 inches need a small diverter roof behind them. Without one, water and debris pile against the uphill face until they find a way in.
What you can check yourself
From the ground, look for lifted or wavy flashing lines and white staining on the brick. In the attic, inspect the chase framing during rain. Note whether leaking follows every rain or only wind from one direction — that distinguishes flashing from crown entry.
When it’s a job for a pro
Chimney flashing is layered, and surface caulk over failed layers just hides the path for another season. Proper re-flashing means lifting shingle courses and cutting a new reglet into the mortar — an afternoon for a roofer, a liability from a ladder.
Re-flashing a chimney typically runs $300 to $1,100; adding a cricket $400 to $900. Crown repairs are masonry work priced separately, usually $200 to $600.
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