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Leaning Chimney or a Gap Between the Chimney and the House
A chimney that tilts, or pulls away from the wall of the house, can be a structural problem rather than a surface one. Here is what causes it, how urgent it is, and who should look at it.
Treat this as a priority: if you can see a gap or a lean, stop using the fireplace and keep people and pets away from the base of the chimney until it has been evaluated. If bricks are falling, or part of the chimney has moved suddenly, keep clear of the area and call a professional right away; call 911 if anyone is in danger.
What you might notice
- A visible gap between the chimney and the siding, brick or framing of the house.
- A chimney that looks tilted against the sky or against the building.
- Cracks in the chimney masonry, or cracks in the hearth, or along the sides of the fireplace inside.
- Smoke or the smell of smoke coming from places other than the fireplace opening.
Home-inspection training material lists “visible tilting or separation from the building” as a defect, and says a leaning chimney can open cracks in the hearth or sides of the fireplace that let sparks or smoke into the home. It also advises measuring a gap over time to see whether it is growing.
Common causes
A chimney is heavy and tall, and it is held up from below and steadied at the sides. Inspection guidance names these issues:
- Footing problems. A footing that is too small, deteriorated by weather and frost, or sitting on poor soil, such as eroded or settled soil, frost heave or expansive clay.
- Missing or inadequate ties. Steel straps or other supports that tie the chimney to the structure at the roof and floor levels may be absent or insufficient.
- Weathered masonry. Mortar that crumbles when poked with a screwdriver is described as a warning sign; tall, narrow chimneys are the most vulnerable to weathering and wear.
- Mechanical damage. Falling tree limbs and similar impacts.
Not every gap means settlement. InterNACHI notes that moisture and thermal movement are often misdiagnosed as settlement, and that horizontal or sweeping cracks can be potentially serious. A thin, stable gap is a different situation from one that is widening, which is why measurement over time matters. If water is also entering around the gap, see chimney flashing repair and why is my chimney leaking.
What a chimney professional does and does not decide
A chimney inspection can check the parts of the chimney that we work on: masonry condition, mortar joints, crown, flashing, the flue and how the chimney meets the structure. CSIA inspection guidance includes looking at the point where the chimney meets the structure and checking for irregularities. See chimney inspection and inspection levels.
Whether the cause is in the foundation, footing or soil is a different question. When a lean or separation looks like it comes from movement of the ground or the foundation, it is reasonable to ask for a licensed structural engineer to evaluate it, and we would not be the right party to diagnose a foundation. A chimney professional and an engineer often work together: the engineer assesses the cause and the structural fix, and the chimney work follows.
Repair directions
| Situation | Typical direction |
|---|---|
| Stable gap, weathered joints or sealant | May involve masonry repair and sealing; see repointing |
| Deteriorated top section | Partial rebuild; see partial vs full rebuild |
| Movement tied to footing, soil or foundation | Engineer evaluation first; then repair or rebuild as directed |
| Missing ties or supports | Evaluate and correct with the engineer or building department as needed |
InterNACHI’s guidance on preventing collapse also notes that you should get permits from the local building department before significant work affecting the chimney or its supports. See permits and contractor documents for chimney work and chimney repair vs rebuilding.
Frequently asked questions
Can I just caulk the gap?
Sealant is sometimes part of a repair, but it does not address the cause, and it can make a growing gap harder to see. Have it evaluated first.
How fast is this an emergency?
A gap that is growing, or loose or falling masonry, should be treated as urgent. Any gap or lean should be assessed rather than ignored.
Do I need an engineer?
Not always. If the inspection points to foundation or soil movement, or the structure looks compromised, an engineer is the right person to consult.
Next step
Request an inspection or call (862) 225-6529 and tell us what you see. AM Chimney Sweep is a registered (NJ HIC #13VH14312300) and insured New Jersey home improvement contractor.
Sources
- InterNACHI, Chimney Inspection: Preventing Collapse (tilting and separation as defects, measuring a gap over time, footing and tie causes, mortar warning sign, moving people away, permits)
- InterNACHI, Inspecting Visible Masonry (sweeping or horizontal cracks, moisture and thermal movement misdiagnosed as settlement)
- InterNACHI, How to Inspect Fireplaces, Stoves, and Chimneys (leaning chimney can open cracks that let sparks or smoke in)
- CSIA, Level 2 Inspection of a masonry chimney (checking where the chimney meets the structure)