Signs your chimney needs cleaning

What you can check from the room

• Smell. A smoky, tarry odor from the fireplace, especially in humid weather, usually means deposit in the flue.
• Soot on the damper or smoke shelf. Shine a flashlight up past the damper. Black buildup you can see is worth noting.
• Fires that are hard to light or burn poorly. A narrowed flue restricts airflow.
• Debris in the firebox. Twigs, leaves or flakes of black material can come from above.

Symptom, cause and next step

What you cannot see from the room

The flue interior is only partly visible from below. Cracks, nests and deposits higher up are not. That is a reason the guidance is to inspect yearly rather than wait for signs. See How often should a chimney be swept?.

A quick checklist

• Black or brown flaky or tar-like deposits visible in the firebox or damper area.
• A strong smoky or tarry smell, especially in humid weather.
• Fires that are slow to start or smoke into the room.
• Soot falling into the firebox.
• It has been a long time since the last sweep.
• Animals, nests or debris seen or heard.

Common misconceptions

"If I cannot see buildup, it is clean." Most of the flue is out of sight.

"Gas fireplaces never need checking." They still need periodic inspection.