What does a cracked chimney crown mean for the rest of the stack?
A cracked crown means water has been getting into the top of the chimney, and the brick, mortar and liner below it may have taken some of that water. Sometimes the crown is the only thing that has failed. Often it is the first visible sign of a stack that is starting to break down from the top.
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What changes the answer is how long the crack has been open. A fine surface crack on an otherwise straight, solid stack is a small repair. A wide crack, a crown that has pulled away, or brick and mortar that look worn just below it point to damage further down, and that is when rebuilding above the roofline comes up.
Why a crown crack reaches the rest of the stack
The crown is the slab of mortar or concrete across the top of the chimney. Its job is to shed rain away from the brick and the flue. When it cracks, rain runs into the crack and into the top courses of brick instead of off the edge.
Once water is inside the masonry, it softens mortar joints, stains and flakes the brick face, and can work down toward the flue liner and the flashing at the roof. Where winters bring freezing, trapped water expands and widens the damage. In any climate, repeated wetting and drying wears the stack away from the top down.
That is why a technician looks at more than the crown. The crack tells you where water is getting in. The brick, joints, liner and flashing tell you how far it has gone.
What you can check yourself
Look at the top from the ground
Use binoculars from a safe spot in the yard. Note cracks in the crown, gaps where it meets the flue, and any pieces that have broken away. Do not climb up to look.
Check the brick below the crown
Look for crumbling faces, mortar that has washed out of the joints, and white powdery staining. These suggest water has been moving through the brick.
Look for debris and lean
Check the ground, patio and lower roof edge for bits of brick or mortar. Stand back and see whether the stack looks straight against the house.
Look and smell indoors
Check the ceiling and walls around the chimney for stains, and the firebox for damp or a musty smell, especially after rain.
Test your alarms
Make sure the smoke and carbon monoxide alarms near the fireplace are working.
When to call a technician
Call once you can see a crack in the crown, because the crown is the cheap part to deal with early and the stack below is not visible from the ground. Call sooner if brick is crumbling, the stack leans, or stains are showing indoors. A fireplace should not be used under a stack that is leaning or shedding brick. If anyone has a headache or dizziness while a fire is lit, get outside and call 911.
One Call Chimney is a referral and scheduling service. One call to (866) 576-7943 arranges an independent sweep or mason. The estimate is free, the technician inspects the chimney and gives the price before any work starts, and you approve it first. Whether a rebuild needs a permit depends on your city and county, so check with your local building department.
What the technician will do
- Inspect and photographThey look at the crown, brick, mortar and liner, and photograph what is failing so you can see it too. Ask to see the photos and for the reasoning in writing.
- Rebuild above the rooflineThis is the usual answer when the damage stops near the top. The failing courses come down and are laid back up.
- Full rebuild where neededIf the structure has gone, a full rebuild with proper footing and flashing is the fix.
- New crown cap and linerA new crown cap and liner are part of the work, so water is shed properly and the flue is protected.
- Match the brick and mortarBrick and mortar are matched as closely as the house allows.
Related questions
- Can a cracked crown just be patched?
- A fine, shallow crack can sometimes be sealed or repaired, provided the masonry underneath is sound. A wide crack or a crown that has separated usually needs a new crown. The technician's inspection decides which.
- Is it safe to use the fireplace with a cracked crown?
- A crack alone does not always make the chimney unsafe, but you cannot see the liner or inner brick from the ground. Have it looked at before relying on it. Do not use it at all if the stack leans or is shedding brick.
- How long can I wait before it gets worse?
- Water enters every time it rains, so the damage keeps building. There is no safe timetable to quote. Having it inspected early often keeps the job to the crown or the top of the stack.
- Will a rebuilt section look different from the old brick?
- The brick and mortar are matched as closely as the house allows. Older weathered brick can never be matched perfectly, but a good match is usually possible.
- What does the estimate involve?
- One Call Chimney arranges the visit, and the estimate is free. The technician inspects the chimney and gives you the price before any work starts, and nothing begins until you approve it.
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One Call Chimney arranges the visit; the technician does the work and gives you the price.