Why does my chimney leak when it rains?

When a chimney leaks only in the rain, the water is usually getting in at one of four places: the flashing where the chimney meets the roof, a cracked crown, a missing or damaged cap, or worn mortar in the brick. Flashing is the one I check first, because it's the most common leak spot on a chimney.

If you want me to take a look, text a picture to 443-900-4815 or call the same number. I'm James. I've worked on roofs and chimneys around Baltimore City and Baltimore County for 24+ years, and I'm licensed and insured, MHIC #154344.

Where does the water get in?

• Flashing. The metal where the chimney meets the roof. It loosens, rusts, or pulls away from the brick, and water runs behind it. Old patches of tar over flashing usually mean it's been leaking before. See chimney flashing repair.
• The crown. The concrete or mortar slab that caps the chimney. Once it cracks, water goes straight down into the brick. See chimney crown repair.
• The cap. The cover over the flue. Without one, rain falls right down the chimney. See chimney cap installation.
• Brick and mortar. Old mortar joints wear out and soak up water like a sponge, especially on the side that faces the weather. See masonry services.

How can I tell which one it is?

Where the water shows up is a good clue:

• On the ceiling or wall right next to the chimney: most likely the flashing.
• Inside the fireplace or firebox: most likely the cap or the crown.
• Damp or stained brick inside, or white chalky stains on the outside brick: the brick and mortar are taking on water.
• Only in wind-driven rain from one direction: often the flashing or the brick on that side.

If the chimney drips in dry, cold weather, or the stains are on the flue itself, it may not be rain at all. That can be condensation inside the flue, and the flue and liner are a chimney sweep's call. We work on the outside of the chimney: flashing, crown, cap, and brick.

Is a leaking chimney urgent?

A small drip can usually wait for a dry day, but not for months. Water that gets into brick freezes and expands in the winter, which cracks the brick and mortar further. It can also rot the wood framing around the chimney inside the roof.

What we do

1. Look at the whole chimney, from the roof when it's safe. On a steep or tall roof I can use the drone. I'm an FAA-licensed drone pilot.
2. Find where the water is really getting in, not just where it shows up inside.
3. Send you pictures of what we found, with a price before any work starts.
4. Fix the source: reflash, repair or rebuild the crown, put on a cap, or repoint the brick.

You can text me at 443-900-4815 with a picture of the stain and the chimney, or call the same number.

Chimney leak questions

Why does my chimney only leak in heavy rain?

Heavy or wind-driven rain gets into spots a light rain doesn't, like loose flashing on the uphill side or worn mortar on the side facing the weather. Note which way the wind was blowing when it leaked.

Who fixes a leaking chimney, a roofer or a chimney sweep?

For flashing, the crown, the cap, and the brick on the outside, a roofer who does masonry. For the flue and liner inside the chimney, a chimney sweep.

Can a leaking chimney be fixed without rebuilding it?

Usually, yes. Most chimney leaks are flashing, a crown, or a cap. A rebuild is only needed when the brick above the roof is loose or falling apart.

Can a cracked chimney crown cause a leak?

Yes. Water goes through the crack and down into the brick, and it often shows up as stains near the fireplace after rain.

How much does it cost to fix a leaking chimney?

It depends on what's leaking and how easy the chimney is to reach. Flashing or a cap is usually a smaller job than a crown or brick work. You get a price before any work starts.