Top Causes of Foul Fireplace Odors

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Top Causes of Foul Fireplace Odors


Fireplace odors can be indicative of serious problems that should be addressed before using them as the weather starts to cool.  Some smells are obvious, and will be detectable when the fireplace is not in use.  Others may start to permeate the room once you use the fireplace for the first few times during the season.  In any case, it’s important to know what causes common odors and how to deal with them.



Animals represent probably the largest source of odors in fireplaces.  This can be from them choosing to use the top of the chimney as a nest, getting stuck and dying, burned or from their waste products.  One way to prevent animal intrusions is to put a screen or some chicken wire and a cover around the top of the chimney.  You may have to remove a dead animal if it gets stuck and blocks smoke from exiting the chimney as well. 



Smoke that doesn’t exit all the way out of the chimney, either by blockage or a lack of force, can flow back into the room as it cools.  Keep in mind that smoke contains particles that will also fall instead of being carried away once the fire starts to die off as the force of the vacuum that sucks smoke out diminishes.   The thing about smoke is that you may not notice it until a day or two later as the material settles on furniture or carpeting.  The best way to reduce smoke-related problems is to have good fireplace doors that close tight after use.  When the fire dies out, the smoke will remain trapped inside as the particles drift to the bottom while remaining inside the fireplace.

Dirty Fireplaces


As fireplaces are used over time, an accumulation of greasy ash forms along the walls of the chimney.  This is generally called creosote, and it is dangerous.  Not only is it very flammable, but burning creosote can inject carbon monoxide into the room.  It’s also stinky, and these smells can permeate a room even when a fireplace is not in use.  It’s important to get a good chimney cleaning on a periodic basis in order to reduce hazards along with foul odors.



Precipitation can also cause odors to come from the fireplace, most often in the form of a moldy, dingy smell.  The best way to reduce this problem is to put a cover on top of the chimney that will deflect rain or snow down the sides instead of letting it drip inside.  These covers are usually peaked or rounded, like an inverted bowl, that are attached to some supports that keep it a few inches above the top exhaust of the chimney.  They are easy to install, as long you can reach the chimney top safely.

Pressure in the Home

Many homes, especially newer ones built over the past few decades, are designed to be as airtight as possible.  While this makes them more efficient in terms of retaining cool or heated air, they may not be designed with fireplaces in mind.  When a fireplace is burning, it takes oxygen from the surrounding area, and the air gets sucked up and out of the chimney.  Once the fire has gone out, the opposite is often true, and the air will get sucked down through the chimney and end up back inside.  It picks up chimney smells on its way back down.  A good flue and tight-fitting fireplace doors can help to mitigate this problem. 

The good news is that addressing most problems is not complicated, and these are the most common examples and solutions to consider.  A good inspection of the fireplace and chimney before being used in the upcoming season can help to prevent bad smells from occurring in the first place.  Doing so will allow you to take corrective action while helping to ensure that you get the most out of your fire while minimizing odors at the same time.