Quick answer: Your chimney may not be safe to use if it hasn't been inspected in over a year, if you see a shiny black glaze inside the flue, if smoke backs into the room, or if you notice cracks in the masonry or crown. The two biggest risks are chimney fires (from creosote) and carbon monoxide (from a blocked or damaged flue). When in doubt, don't burn — get an inspection first.
The two real dangers
Chimney fires. Creosote, the residue from burning wood, is highly flammable. Enough buildup can ignite inside the flue and spread to your home — a single chimney fire can cause $4,000–$20,000 in damage. Warning signs of a past chimney fire include puffy or "honeycombed" creosote, cracked flue tiles, and a warped damper.
Carbon monoxide. A blocked, cracked, or dirty flue can push carbon monoxide — colorless and odorless — back into your living space instead of venting it outside. This is why a working chimney matters even for gas fireplaces.
Signs your chimney is NOT safe to use right now
- Shiny, glazed black creosote inside the flue
- Smoke spilling into the room when you light a fire
- Visible cracks in the crown, masonry, or flue tiles
- Water stains inside the firebox or on nearby walls
- No inspection in more than a year
- A strong, persistent burning or tar smell
What makes Chicago-area chimneys higher-risk
Our 20–30 freeze-thaw cycles each year crack crowns, open mortar joints, and damage liners — often invisibly. That's why a chimney that "looks fine" from the ground can still be unsafe. A Level 2 video inspection is the only way to see inside the flue.
The safe move
If you're unsure, don't burn until it's been checked. GEM provides inspections with a written report so you know exactly what's safe and what needs attention — with upfront pricing and same-day scheduling. Registered in Illinois and fully insured.
Call 773-900-4838 for a safety inspection. This article is general safety information. If you smell gas or suspect carbon monoxide, leave the home and call 911 or your gas utility immediately.