Chimney crown repair in New York City
The crown is the slab on top of your chimney that sheds rain, and once it cracks, water runs straight into the brickwork beneath it. We seal and coat a crown with hairline cracks and rebuild one that has broken.
Chimney crown repair, explained
The crown is the layer of mortar or concrete that covers the top of the chimney stack around the flue. Its job is to shed water: rain should run off its surface and away from the brick, not soak down into the stack.
Crowns crack for ordinary reasons. They sit in full sun and full weather, and water that gets into the surface freezes and widens whatever small cracks are there. Many crowns were also made from the same mortar used to lay the bricks, spread thin across the top, and that mix was never meant to work as a roof.
Crown repair comes in two sizes. When the crown is solid and the cracks are fine, the surface is cleaned, the cracks are filled, and the whole crown is covered with a waterproof coating that flexes with the weather. When the crown is loose, crumbling or cracked right through, coating it only hides the problem, so it is broken out and a new crown is formed, sloped so water runs off.
The crown is not the cap. The cap is the metal cover over the flue opening, and if that is your problem, see cap replacement. The two are often done together, since both sit at the top of the stack.
What is included
- The crown inspected and photographed from the roof
- Loose material, moss and dirt cleaned off
- Cracks filled and the surface coated edge to edge
- The joint around each flue tile sealed
- A broken crown removed and rebuilt with a slope
- The cap checked, and refitted if it had to come off
- Photos of the finished crown
Signs you need it
- Cracks you can see across the top of the chimney
- Chunks of mortar on the roof or in the gutter
- White staining on the bricks just under the top
- Moss or weeds growing out of the crown
- Water in the firebox even though there is a cap
- Loose bricks in the top courses
How the job goes
Inspect the crown
We check how deep the cracks go, whether the crown is still firmly attached to the brick and whether any pieces move, which decides between sealing and rebuilding.
Clean the surface
Dirt, moss and loose mortar are brushed off, because a coating only holds on a clean, sound surface.
Fill and coat
On a sound crown the cracks are filled, then a waterproof coating is brushed over the whole top, from the flue tile to the outer edge.
Or rebuild
A failed crown is broken out down to the brick and a new one is formed, with a slope from the flue to the edges.
Seal the flue joint
The gap where the flue tile comes through the crown is closed with a flexible sealant, since the tile expands when it heats and a rigid joint would crack again.
Photograph it
The cap goes back on, and you get photos of the crown before and after.
From our own jobs
Our photos, not stock.
Why it matters
A cracked crown is the most direct leak a chimney can have. Rain lands on the top and drains through the cracks into the middle of the stack, where it soaks the brick and mortar from the inside.
From there the damage spreads downward. Through each winter the wet masonry freezes and breaks up: the top bricks loosen, the mortar joints wash out, and white stains appear on the outside as salts are carried through the brick.
Sealing a crown that has only hairline cracks is a small job. Waiting until it breaks apart means rebuilding the crown, and often repointing or relaying the bricks under it as well.
Chimney crown repair: common questions
Can a cracked crown be sealed, or does it have to be rebuilt?
It depends on the crown, not the cracks alone. Fine cracks in a crown that is still hard and firmly attached can be filled and coated. If pieces are loose, missing or cracked through to the brick, a coating has nothing sound to hold on to, and the crown should be rebuilt.
How can I tell my crown is cracked if I cannot see the roof?
Mostly by its effects: white staining or damp brick near the top of the chimney, bits of mortar in the gutter or on the ground, or water in the firebox after rain. The crown itself has to be seen from the roof.
Can crown work be done at any time of year?
Coatings and mortar need dry, mild weather to set, so crown work is scheduled around the forecast. Spring through fall is the easy season, and in winter it depends on finding a dry, mild stretch.
What is the white coating on some chimney tops?
That is a crown coating: a brushed-on waterproof layer applied over a sound crown to close hairline cracks and keep water from soaking in. Several of the photos on this page show one. It protects a good crown and does not replace a broken one.
Related chimney services
Tell us what is going on. We will tell you what it needs.
Call or text with your ZIP code and a line about the problem. For dryer vents, text DRYER and your ZIP.