It's Probably the Flashing
When a homeowner calls about a chimney leak — water stains on the ceiling near the fireplace, dampness in the attic around the chimney — the chimney itself is guilty maybe a third of the time. The other two-thirds, it's the flashing: the metal transition where the chimney passes through the roof. Flashing is the single most common source of chimney-related water entry, and the most commonly botched detail on the whole roof.
How Flashing Should Work
Proper chimney flashing is two layers of metal working together. Step flashing — L-shaped pieces woven into the shingle courses — runs up the sides of the chimney, shedding water down the roof. Counterflashing is embedded into the chimney's mortar joints and folds down over the step flashing, so water running down the brick can't get behind it. Done right, water has no path in: every layer laps over the one below, shingle-style, all the way down.
How It Usually Fails
- Caulk instead of metal. The classic shortcut: smearing roofing caulk or tar where counterflashing should be. It looks sealed for a year or two, then it cracks and peels — and now water runs straight behind the step flashing.
- Counterflashing not embedded. Metal just surface-mounted to the brick with caulk will separate as the chimney and roof move differently with temperature. Real counterflashing is cut into the mortar joint and sealed there.
- Rusted or damaged step flashing. Old galvanized flashing rusts through; storm damage bends it; previous roofers sometimes reuse flashing that should have been replaced.
- No cricket on wide chimneys. Chimneys wider than about 30 inches need a cricket — a small peaked diverter on the uphill side that splits water around the chimney. Without one, water ponds against the uphill face and forces its way in.
Our Repair
We remove the failed flashing, inspect the roof deck and chimney base for hidden water damage (there's often some — we'll show you), install new step flashing woven with the shingles, cut new counterflashing into the mortar joints, and add a cricket where the chimney width calls for it. We use quality metal — not the thinnest stock available. On a rebuild, new flashing is included automatically.
Send the form — tell us where you're seeing water (ceiling stain, attic dampness, wall near fireplace) and when it shows up (every rain, only wind-driven rain, etc.). That helps us diagnose before we arrive.