If you are experiencing smoke inside your house when you light your fireplace you must first determine where the smoke is coming from. This first step is very important because depending on where the smoke is coming from you could be in danger of your house catching on fire.
If the smoke is coming from anywhere other than directly out of the front of the firebox opening, that is a dangerous sign because if it is not coming directly from the firebox it
means the fire is not being contained within your fireplace.
If you see smoke coming out or the walls, in the attic or anywhere other than the firebox you should call the fire department immediately!
The only possible problem you should attempt to solve on your own is to check to make sure that you have opened the damper before starting the fire. If it is not the damper then you should call a professional to inspect the problem. The risk of making a mistake trying to repair it on your own is too great.
If it is not the flue being closed then the smoke is being caused by something much more serious.
The flue could be blocked if you do not have a spark arrestor attached to the last segment of flue that sticks out at the top of the chimney. That would allow animals or birds access and it could be a bird’s nest or a dead animal blocking the flue.
Another possibility that sometimes occurs if you do not have a Spark Arrestor is that you could be experiencing a downdraft forcing air down the chimney. This usually occurs when the wind is blowing over a roof ridge or a tree that is near but higher than the chimney. As air is pushed over the ridge it tends to be forced downward. Most times a spark arrestor will solve this problem because it has a solid cap that blocks the downdraft yet still allows smoke to escape through the screens that cover its sides.
Masonry chimneys have cement cap that seals the top of the chimney around the last flue that protrudes above the chimney. This cap can deteriorate with age and crumble allowing the flues to shift out of alignment creating a dangerous situation.
The last and most dangerous cause of the smoke is the integrity of the firebox or the flues above the firebox have become compromised.
The firebox or the masonry above the firebox can become burned out and deteriorate over time allowing sparks or fire to escape before the top of the chimney. I cannot overemphasize how dangerous this is.
The bottom line is that if you fired up your fireplace and had smoke enter your house, call a professional immediately.