If the room is filling with smoke and not clearing, get everyone out and call 911. If it puffed once and cleared, let the fire go out, then work through the causes before lighting another.
Smoke entering the room means the flue is not carrying it away, and the first thing to establish is whether the room is clearing or filling. A room that is filling with smoke and not clearing is an emergency: get out and call 911. A puff at startup that clears once the fire establishes is a draft problem, and draft problems have a short list of causes worth working through in order. A cold flue that has not been warmed will not pull. A blocked cap, screen or flue will not pass smoke at all. A damper that is not fully open restricts it.
A house under negative pressure from a running dryer, range hood or furnace can reverse a chimney outright. And a flue that is undersized relative to a fireplace opening, or a chimney too short for its roof, will never draw correctly no matter what you do on the day.
Checks you can do safely
- Confirm the damper is fully open before anything else
- Turn off the dryer, range hood and bathroom fans and try again
- Crack a window in the room and see whether the behaviour changes
- Warm the flue with a rolled paper held up in the throat before lighting
- Look up the flue with a torch for an obvious blockage
- Check the cap from the ground for a nest or an obvious obstruction
- Note whether it happens always, only at startup, or only on certain days
Smoke in the room: causes in the order worth checking
Stop using the appliance until it has been inspected
| Possible cause | Rank |
|---|---|
| A cold flue that has not been warmed before lighting | Most common |
| A blocked cap, spark screen or flue: nests, debris, snow or ice | 2 |
| A damper not fully open, or one that has warped and no longer opens | 3 |
| House negative pressure from a dryer, range hood, bath fan or furnace | 4 |
| A flue undersized relative to the fireplace opening | 5 |
| A chimney too short, or terminated too low relative to the roof | 6 |
| Heavy creosote narrowing the flue | 7 |
| Wind conditions and nearby trees or buildings causing downdraft | 8 |
Services this maps to
Related problems
- Chimney Draft Problems: My Stove or Fireplace Will Not Draw
- I Think I Had a Chimney Fire: What to Do Next
- The Carbon Monoxide Alarm Went Off: What to Do
- My Chimney or Fireplace Smells: Why, and What Fixes It
If what you have is not smoke in the room after all, the full list of chimney problems is grouped by urgency, and the service triage tool takes a symptom and returns the stop condition and the service it maps to.
Common questions about smoke in the room
When is smoke in the room an emergency?+
When the room is filling and not clearing: a get-out-and-call-911 situation. A single puff at startup that clears as the fire establishes is a draft problem to diagnose, not an emergency, and the difference is whether it clears.
Why does it only smoke when I first light it?+
Because the flue is cold and full of dense cold air that has to be displaced before the chimney will pull. Warming the flue first, a rolled newspaper or fire starter held up in the throat until you feel the draft turn over, solves a great many startup puffs.
Why does it smoke when the dryer is running?+
Because the dryer is pulling air out of the house and the house is replacing it through the easiest opening, which can be your chimney running backwards. Turn the dryer off and the behaviour commonly changes immediately, which is a useful diagnostic in itself.
Would cracking a window help?+
Often, and it is worth trying because it tells you something. If opening a window in the room fixes it, the problem is that the house cannot supply enough air, and the durable fix is a make-up air provision, not anything done to the chimney.
My fireplace has always smoked. Can that be fixed?+
Commonly improved and sometimes fully. Where the cause is a flue undersized for the fireplace opening or a badly built smoke chamber, the effective remedies are reducing the opening, correcting the chamber, or fitting an insert vented through a correctly sized liner.
Could the chimney be blocked?+
Yes, and a sudden change from drawing well to not drawing at all points strongly at a blockage. Nests, leaves, a collapsed tile, a blocked spark screen and snow or ice at the termination are the usual ones, and a sudden change like that is a stop-using-it symptom.
Does wind cause this?+
It can. Wind over a nearby roof, a hill or tall trees can create pressure conditions that push down a chimney. If the problem is strongly linked to wind direction, that points at termination height or position instead of at anything inside the flue.
Could the chimney be too short for the roof?+
It can be, and it is a classic cause of chronic downdraft. There is a recognised relationship between where the flue terminates and the roof around it, and a stack finishing too low relative to its own roofline never draws correctly. Termination height is measured, not judged by eye.
Can heavy creosote cause smoking?+
Yes. Deposit narrows the flue and reduces its capacity, so a chimney that drew adequately when clean can stop coping when loaded. Heavy creosote is one of the more easily fixed causes, and it is also a reason not to keep burning while you investigate.
Should I keep using it while I work this out?+
No. Smoke in the room means combustion products are entering your living space, and carbon monoxide comes with them without any smell. Let the fire go out, work through the causes cold, and get it looked at if the simple checks do not resolve it.
The stove smokes when I open the door.+
Some of that is normal if you open it fast on an active fire: open slowly and let the pressure equalise. Persistent smoke on opening points at weak draft, and the same list of causes applies as for a fireplace.
What will a technician check?+
The damper, the flue for blockage and deposit, the smoke chamber, the cap and termination, the flue-to-opening proportion on a fireplace, and the house pressure conditions. The last one is the most commonly missed and the most commonly responsible on newer houses.