Why Is Smoke from My Fireplace Backing up into My Home?

Smoke inside a home is no fun. But if your fireplace is backing up, smoke isn’t your only concern. The biggest issue is the carbon monoxide carried in the smoke.

Carbon monoxide is both invisible and odorless, but it is known to be potentially fatal to people and pets when inhaled.

For this reason, you want to make sure that your fireplace and chimney aren’t causing smoke to back up into your home. Here are some common causes of backups and what you can do about them.

Chimney Flue blockage

Smoke will draft sluggishly and often back up into your home if your flue is obstructed. Common obstructions include:

Built-up creosote, a sticky, solid, puffy or flakey substance that accumulates every time wood burns in your fireplace

Outside debris such as leaves, twigs and the nests of small animals. Creosote issues are solved by having a professional chimney cleaning on a regular basis.

Debris issues are prevented by having a secure full-width chimney cap installed.

Negative air pressure

If something in your home is drawing air out of the house (a stove fan, a clothes dryer, a bathroom fan, etc.), it could create just enough of a negative draft to keep air from properly moving into the fireplace to draw smoke up the chimney.

With some experimentation, you can find out what you can and can’t run while your fireplace is in use.

House too air-tight

Newer homes are built a lot more air-tight than older homes. They can be so air-tight that the natural action of the flue to pull in drafting air is prevented.

The solution usually is cracking a window near the fireplace.

Cold flue air

Cold air is denser (heavier) than warm air. If you get a fire going and the air in your flue is particularly cold, warm smoke will have trouble making its way out of the chimney.

If this is the reason for smoke backing up into your home, try holding a tightly rolled and lit newspaper up into the flue for a few moments. A hair blow dryer also can help to warm the air inside the flue. A secure chimney cap may keep some cold air from entering your flue.


Strong winds outside can blow down into your chimney and send smoke and debris into your home.
This is most common in chimneys without proper chimney caps or with caps that are severely damaged. A good chimney cap is the best way you can block the wind.

Ask your chimney professional about specific chimney covers designed for homes in particularly windy areas.

chimney sweep replacing a chimney liner in Dover NJIncorrectly built chimney

The reason fireplace/chimney systems work as well as they do is due to the flue or chimney liner being the correct size for the fireplace. Chimneys that were built incorrectly and flue liners that were installed in the wrong size can lead to serious drafting problems.
If you’ve taken all the steps listed here and are still having smoke backups, it’s time to bring in a licensed chimney inspector to look at your system.

A professional chimney inspection will determine the exact cause of the problem and give you recommendations on how to fix it.

Make sure your chimney works great every time you use your fireplace

For more than 20 years, National Chimney Service has provided licensed chimney inspections, chimney repairs, resolution of drafting issues and complete chimney cleaning throughout the Fairfield County, CT, and Morris County, NJ, areas.

When you’re having problems with your chimney, our crews are standing by to help. Call us first at 800-631-6177.


Use an Experienced, Established Chimney Sweep Company!

Don’t take chances with uninsured, novice, roofers, unregistered business, no workman’s comp.
Our pros have to know what they’re doing when they put their heads up a chimney and to do that, chimney sweeps obtain specialized training and have years of experience in the field.