Why Is My Roof Leaking Around the Chimney?

Why is my roof leaking around the chimney?

Published October 13, 2026 · John Beal, Owner, John Beal Roofing

Usually it's one of three things: cracked or loose flashing, a cracked crown on top of the chimney, or crumbling mortar between the bricks. Don't just slap caulk on it. Fix the real cause.

If you have a water stain on the ceiling near the chimney, or damp spots on the wall beside the fireplace, you're in good company. Chimneys are one of the most common places a roof leaks. The good news is that the cause is usually one of three things, and each one has a real fix.

Cause one: cracked or loose flashing

Where your chimney comes through the roof, there's a gap between brick and shingles that has to be sealed. Flashing does that job. It's metal, layered with the shingles on the roof side and tucked into the brick on the chimney side, so water runs past the joint instead of into it. Over the years, flashing can crack, rust, or pull loose from the mortar. Sometimes it was never installed right. Either way, rain runs down the face of the chimney and straight into the gap. This is the most common chimney leak we see.

Cause two: a cracked crown on top

The crown is the slab of concrete or mortar on top of the chimney, around the flue. Its job is to shed water off the top and away from the bricks. Freezing and thawing winter after winter cracks it. Once it cracks, rain and melting snow soak straight down into the chimney, and the water shows up wherever it finds a way out, which is often right where the chimney passes through your roof.

Cause three: crumbling mortar between the bricks

Brick and mortar soak up water. When the mortar joints start to crumble and wash out, the chimney takes on more water than it can shed. That water travels down inside the masonry and can appear as a leak near the roof line, even when the flashing is fine.

Don't just slap caulk on it

The most common "fix" for a chimney leak is a tube of caulk run around the base of the chimney. It might stop the drip for a season. But caulk doesn't fix failed flashing, a cracked crown, or bad mortar. It just hides them until the next big storm, while water keeps working into the wood underneath.

Fix the real cause

That means figuring out which of the three it is, or whether it's more than one. A good inspection looks at the flashing on every side of the chimney, the crown on top, and the condition of the brick and mortar, plus the ceiling and attic below. If you're replacing your roof, it's also the perfect time to put new flashing around the chimney rather than reusing old metal.

What we do

We look at the whole chimney, not just the spot where you saw water, and tell you straight what's causing it. If it's leaking in the middle of the night, call anyway. We answer 24/7.

What John says in the video

Transcript: Why is my roof leaking around the chimney? Usually, it's one of three things: cracked or loose flashing, a cracked crown on top, or crumbling mortar between the bricks. Don't just slap caulk on it. Fix the real cause. Call me. 1-800-JOHN-BEAL.

Frequently asked questions

What is chimney flashing?

It is the metal that seals the joint where the chimney meets the roof. When it cracks, loosens or was installed wrong, water runs down the chimney and into the house.

What is a chimney crown?

The crown is the cap of concrete or mortar on top of the chimney that sheds water away from the bricks. A cracked crown lets water soak down into the chimney.

Can crumbling mortar cause a roof leak?

Yes. Water can soak into the bricks and gaps in the mortar and travel down inside the chimney, showing up as a leak near the roof line or on the ceiling.

Why not just caulk around the chimney?

Caulk covers the symptom. If the flashing has failed or the crown is cracked, water keeps finding a way in, and the caulk just buys a little time.

Who can fix a leak around my chimney?

We can inspect the flashing, crown and mortar and tell you which one is the problem. Call 1-800-JOHN-BEAL, answered 24/7.