Cracked crown at the top

Crown damage is easy to miss because it’s at the very top of the house. It often shows up first as flaking brick near the top of the stack, or water inside the chimney.

1Why crowns crack

• Built with mortar. Many crowns are just a mortar wash smeared across the top. It’s weaker than a proper concrete crown and cracks sooner.
• No overhang. A crown that doesn’t extend past the brick lets water run straight down the face of the chimney.
• No gap at the flue. The flue tile heats and expands. A crown bonded tight to it can crack as the tile moves.
• Freeze-thaw and age. Every winter widens small cracks a little more.

2How to check what you’re dealing with

1. Look from the groundWith binoculars, look for cracks, missing chunks, or plants growing on top of the chimney.
2. Check the top courses of brickFlaking brick or crumbling mortar near the top suggests water is getting in from above.
3. Look insideWater in the firebox, rust on the damper, or white staining on the flue can point to a crown or cap problem.
4. Ask at the inspectionAsk the inspector to photograph the crown so you can see it yourself.

3Fixing it

A properly built replacement crown slopes away from the flue, overhangs the brick with a drip edge, and leaves a flexible gap around the flue tile. Ask the contractor to describe how theirs will be built.

4What drives the cost

Sealing small cracks is the low end. Replacement costs depend on the chimney’s size and number of flues, roof height and pitch, and whether the top courses of brick also need rebuilding. Fixing it early keeps it a crown job instead of a masonry job.

Chimney cost

6Related chimney problems

• No cap on the flue
• Staining on the ceiling around the chimney
• Unlined flue on an older chimney
• Creosote build-up in a wood-burning flue
• Carbon monoxide alarm sounding
• Spalling brick on the exterior stack
• Gas appliance venting into an old flue

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