A crack needs context: location, movement, water entry, and the surrounding masonry. Widening cracks, leaning, or loose masonry call for keeping clear and prompt professional evaluation.
Updated September 10, 2026
Your home in Chicago.
About 78% of occupied homes in Chicago heat primarily with utility gas. Many chimneys in Chicago therefore vent a gas furnace, boiler, or water heater rather than a wood fire, and those flues still need inspection for liner condition, moisture, and blockage. Fewer than 0.1% of occupied homes in Chicago use wood as their primary heating fuel. Most fireplaces in Chicago see occasional use, and even occasional use calls for an inspection before the heating season. The nearest NOAA climate normals station (Chicago Northerly Island, about 4 miles from the Chicago city center) averages 5,786 heating degree days per year. That is a substantial heating season, so plan inspections before the first fire and look for new water or masonry changes after winter from a safe position.
What you can observe safely
- Photograph visible cracks safely from ground level.
- Keep any earlier photos for comparison.
What to avoid
- Do not climb onto the roof or enter the chimney.
- Do not alter gas components, venting, or safety controls.
- Do not use a test fire to diagnose the problem.
Possible causes to assess
- Masonry or mortar deterioration
- Movement requiring assessment
- Water-related damage
A symptom cannot establish the cause remotely. An assessment of the complete system helps determine the appropriate repair.
Chimney repair in ChicagoA few common questions
Can this be diagnosed from a photo?
A photo can document a symptom and help prepare a visit. It cannot confirm concealed conditions or establish that a chimney or fuel-burning appliance is safe.