How do you check a chimney for safety?
Short answer. Check a chimney for safety by looking at the outside for cracks, leaning, missing mortar, a damaged crown or cap and loose flashing, then inside at the firebox, damper and flue for cracks, creosote and blockages, and finally making sure working carbon monoxide and smoke alarms are installed. Anything beyond a visual check, especially the flue liner, needs a professional chimney inspection.
Outside, from the ground
- Is the chimney straight, or leaning away from the house?
- Missing or crumbling mortar, and cracked or flaking bricks (spalling).
- White staining on the brick, which means water is moving through it.
- A cap with intact mesh on top, and no visible damage to the crown.
- On framed chimneys, rust streaks below the chase cover or loose siding.
Where the chimney meets the roof
- Step flashing and counterflashing intact and tight to the brick.
- No gaps filled only with caulk or tar.
- A cricket on the uphill side of wider chimneys.
- Use binoculars or drone photos rather than climbing.
Inside
- Firebox bricks and mortar intact, with no cracks or gaps.
- A damper that opens, closes and seals.
- A flashlight look up the flue for buildup, debris or nests.
- Stains or damp spots on walls and ceilings near the chimney.
Safety equipment
- Working carbon monoxide alarms on each level and near bedrooms.
- Working smoke alarms.
- A fire extinguisher nearby and a screen or doors on the fireplace.
- Furniture, rugs and other combustibles kept back from the opening.
When to call a professional
The flue liner is the most important safety part and the hardest to see. A yearly inspection by a certified sweep is the standard, with a camera scan after a chimney fire or when buying a home. See chimney leaks and crickets and what to expect from a roof inspection.