Chimney leaking when it rains: flashing, crown, or the brick itself

A ceiling stain beside the chimney, a wet attic rafter after a storm, or drips on the hearth all get called a chimney leak, but water can get into a chimney four different ways and each one has a different fix. The flashing at the roofline is the most common, and on Evansville houses it is usually flashing that was caulked to the brick face instead of set into the mortar. Resetting counter-flashing runs $200 to $600 alongside other chimney work. Before paying for any of it, spend ten minutes finding where the water actually comes in.

Find the entry point first

1. Go into the attic during or right after a rain. Look at the framing where the chimney passes through the roof. Wet wood on the uphill side of the chimney points at the flashing or a missing cricket. Wet brick inside the attic, with dry framing, points at water coming down through the stack itself.
2. Note what kind of rain did it. A leak only in wind-driven rain from one direction is usually the brick or the joints on that face soaking through. A leak in any steady rain is more often flashing, the crown, or an open flue.
3. Look at the stack from the ground with a phone zoom. Check the metal where the chimney meets the roof: is the top edge tucked into a mortar joint, or sealed to the brick face with a bead of caulk or roofing tar? Tar smeared over the corners is a sign someone has chased this leak before.
4. Check the top. A cracked crown or no cap over the flue sends water straight into the stack. The cracked chimney crown page shows what a good crown looks like.
5. Watch for wet that has nothing to do with rain. Water stains near a furnace or water heater connection that appear on cold, dry days can be condensation from a gas appliance venting into an unlined or oversized flue. That is a flue problem for a chimney sweep or HVAC tech, not a masonry leak.

What is usually wrong

Every range above is on the pricing page, and the chimney repair cost estimator prices a combination of them in a minute.

Why caulked flashing fails

A chimney is flashed in two layers. Step flashing is a set of bent metal pieces woven in with each course of shingles up the sides of the chimney, so water runs over each piece and onto the shingle below. Counter-flashing covers the top edge of the step flashing so water running down the brick cannot get behind it. To do that job the counter-flashing has to be let into the brick: a slot, called a reglet, is cut about an inch deep into a mortar joint, the bent edge of the metal goes into it, and the slot is repointed or sealed.

The shortcut is to lay the metal flat against the brick and run a bead of caulk along the top. It looks finished from the ground. Then the brick and the metal move at different rates with every hot afternoon and cold night, the caulk tears away from the face, and water runs down the brick, behind the metal and into the roof deck. Recaulking repeats the same failure, which is why so many leaks around a chimney come back every spring.

Wide chimneys need a cricket

A chimney that sits partway down the roof slope works like a dam: water and leaves pile up against its uphill face, and no flashing is watertight under standing water. The International Residential Code (section R1003.20) requires a cricket, a small peaked roof built behind the chimney to split the water around it, when the chimney is more than 30 inches wide across the slope and does not sit on the ridge. Plenty of older houses with wide chimneys were built without one. If the leak is on the uphill side and the chimney is wide, the fix is a cricket from a roofer plus counter-flashing set into the brick, and doing only one of the two leaves the leak.

When the brick itself is the leak

Brick and mortar are not waterproof. A sound stack sheds most of what lands on it and dries out between storms. Once joints erode, wind-driven rain goes straight in through the open joints and runs down inside the masonry until it finds the roof deck or the attic. That leak looks like flashing but survives a flashing repair. The fix is repointing the stack, and on a chimney with spalled brick faces near the top, see the spalling brick page before deciding between repointing and a rebuild from the roofline.

What to send us

Photos from the ground of each face of the chimney, a close shot of where the metal meets the brick, and a photo of the wet spot in the attic or on the ceiling. Tell us whether the leak shows up in every rain or only with wind from one direction. That is usually enough to say which of the four it is before anyone gets on the roof, and to quote it with a crown, cap or repointing on the same trip if those need doing too. We work across Evansville, Newburgh and Henderson, April through November.