Creosote Odors fireplace problems

Creosote Odors

Oh my goodness do they ever stink up a home!

I couldn’t tell you how many times that I have been called by frustrated customers, telling me they have a horrible odor that is filling their home from the fireplace. Being in the business over 30 years I have found that most odor problems stem from one of two things:


Either there is something dead in a chimney such as birds, squirrels or a big old nasty dead raccoon. Not going into detail here, trust me that is not a fun job to remove!


The second and most common culprit is creosote. Creosote is from smoke that contains droplets of unburned carbon and is often referred to as tar-fog. These tar-fog droplets often will condense and collect on the cooler interior walls of both the fireplace and chimney flue system. Creosote is a black flammable substance that is left in a fireplace or wooding burn stove.

Burn smart!

Hot fires from burning cardboard or paper can easily flame up past the damper area and ignite droplets of creosote. Now you have an unfriendly or possibly an out of control chimney fire. Know well that many chimney-fires are much quieter and are referred to as being “slow burning”. These still cause a huge amount of damage to the interior of the fireplace masonry, framing and mantels.

Negative Pressure

Now lets get back to identifying and solving your fireplace odor problem. Over the years I have tried many concoctions’ of home remedies. I have read a lot regarding house pressures induced odor problems. I have purchased many of these odor products. Using those fresh-air smelling small carbon jell tubs, vinegar filled bowls or chimney cleaning logs all work to some degree. But they do not offer a lasting solution for stinky fireplaces. I’m sorry to report to you, but these pungent odors don’t seem to be able to mask enough to satisfy for myself, or my customers’ noses’.

Wood Sources

So let start with your wood source. As we discussed, incomplete combustion may sound high tech. In reality it boils down to your firewood is not being burned completely. Also the fireplace may not be drafting up enough to properly flush those smokey-gases out of your homes fast enough.

In other words, the smoke is lingering in the chimney flue way too long. It is then condensing into creosote and collecting on the cooler walls of the fireplace. Then when your furnace system kicks on, the air pressures within your home are often reversed. This pulls odors down and re-distributes them throughout the home.

How dry is the wood?

Whenever I’m called out to a customer’s home for an odor problem, as soon as I arrive I go looking for their woodpile. I want to see if the wood is covered properly from those soaking snowfalls and spring rains and if it is it soaking wet?

Wet unseasoned wood burns slow and will often make a hissing sound as it is steaming the water out. I’ll check to see if is it appears to be a hard wood or not. Most important is the wood seasoned.

Not necessarily seasoned…

Just because the woodpile appears to look gray or weathered, it does not indicate to me that it is seasoned properly. Looking at the butt end of the wood is it smooth like it was just cut recently? Or does it have lots of weathered cracked ends? This cracking is caused by the moisture being dried out of the wood. For properly seasoned wood, it is often cut, stacked and has a waterproof covering. It should have a moisture content after seasoning of 15% to 25%. Use a moisture meter like this:

Cold Air Returns

When I enter a home, I’m questioning, where are the cold air returns in the room? Is there a cathedral ceiling? What is the proximity to the stairwell in relationship to the mouth of the fireplace opening?

Did you know that a stairwell could produce a much stronger up draft than the actual fireplace? This is especially true while starting a fire. I recommend starting off with smaller fires. It takes about 45 minutes to heat cold masonry up to draw properly. Smoke and odors will follow the path of least resistance. High cathedral ceilings and stairways can be very problematic to the air balance.

The locations of your furnace cold air returns within the home can be very critical in creating a sluggish draft. This is especially true when starting up your fireplace. Also leaving large amounts of ash in the fireplace can actually hold moisture and odors. Be sure to remove these ashes if you’re having an ongoing problem.

Don’t choke the damper!

To often I have gone to homes where the customer is choking the fireplace damper down, they are doing this to create a much longer burn time. Often this smoke is getting up to the top of the chimney, but it is now collecting on the spark arrestor screening. This sluggish draft is now lingering way to long and this creosote is now collecting on the walls of the flue system, as well as the screening. This is way to often the case for my wood stove burning customers.

Spark Arrestor

Be sure to check the spark arrestor, as you drive off to work or are taking the kids to school take a look back at your chimney top is your spark arrestor clear of blockage or not?

Be sure to check the spark arrestor, as you drive off to work or are taking the kids to school take a look back at your chimney top is your spark arrestor clear of blockage or not?


Like most things in life, most problems need to be resolved by a process of elimination.

Here are my possible solutions to your stinky fireplace problem!

imgres-1) In early spring before your AC kicks on have your fireplace cleaned by a professional chimney sweep. You can find a reputable Chimney Sweep in your area by using this link to the National Chimney Sweep Guild locator  Also be sure and go online and read their customer reviews from Google, BBB and AngiesList. I’m never impressed with those cheaper “Swab and Rob companies

2) Only burned wood that has been seasoned properly for at least 6 months.

3) Coverer your seasoned firewood.

4) Don’t choke your fireplace damper down so much!

5) Consistently monitor the spark arrestor on the top of your chimney cap.

* Let me Know if this help with your odor problem or not!

Burn safe and warm!

Clay Lamb
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6 thoughts on “Creosote Odors fireplace problems

  1. How do I know the chimney sweep was able to get rid of all the creosote?
    Does a chimney sweep check the cap on chimney for any creosote?
    Is creosote a mold? How/why does it develop?

  2. It might be a little late for that question. Unless you are willing to now pay for a return trip to run a video. BEFORE packing up our equipment we are glad to show the customer on our video camera the condition of the flue. It gets expensive to question it after the job is completed and the equipment is loaded . Also reading customer reviews is wise “prior to hiring” or allow any contractor into your home. Regarding creosote on the screen on the cap this is often evaluated with binoculars from the ground. Be cautious of shiny smoke stain that can be deceiving. As long as we can sweep the chimney and can then mount the roof in safe weather and on a walkable 5/12″roof pitch, we will. That is as long as it can be done by one man with our 28′ standard ladder that have top rung hight of apx, 20foot from the ground. This is standard practice on our level one inspection and sweeping service call…… Levels of inspections

  3. I have burned wood for many years in my early years here at this address. I have a liquid creosote problem every time I start our fire. Our old chimney was taken down as it was pulling from the house. We waited many years before rebuilding it from the clean out up. This liquid fills my clean out and runs down the inside wall. This problem also existed with our old chimney but not in its early years. My question is, why do I still have this creosote problem with a brand new chimney?

  4. Greetings Dan,
    I will assume your speaking in regards to using a wood-stove in this instance, If it is a fireplace that your addressing many of these hints should be helpful,
    so let me start by throwing out a few things to check on.

    – First is the square inches of the interior of the flue tile the same as the outlet of the heating appliance?
    Most stove manufactures require that the same venting square inches of the top or back of the stove, continues up to the top of the chimney flue, “no bigger or smaller”.
    Squares well as rectangle shaped flue tiles most often will not daft as well as the rifling effect you get when using a insulated round chimney flue liner.
    As a side bar the consistence of the flue size is also require in masonry fireplace constructon.
    Often down sizing of a chimney flue connector can be found where your stove vents into a wall breech opening.

    -Speaking from my own “bad experience”, 90-degree elbows tend to stall the draft; long horizontal connections can be problematic as well.
    If your using a horizontal connector, be sure to keep a 1/4” minimal rise running from the appliance to the wall opening and as short as possible.

    – In your part of the country, “if your legally aloud “ to remove the screening from the chimney cap lid, personally I would do this during the burning season.
    Cold screening material that is to small in the opening size (screen door sizing) can clog quickly hampering the chimney daft during those log cold nights; the stove is not being attended to.
    Many places out West where forest fires often occur a 5/8” screen size opening is required for a spark arrestor, where as in many other parts of the country allow for larger 3/4 “ expanded screen spark arrestor openings

    – When testing this controlled condition, besure to journal this practice by time and differing weather conditions,as you may possibly discover a contributing factor.

    – Is your woodpile covered on top (like a shower cap) to prevent any snow or rain soaking down into your wood supply?

    – Is your wood truly seasoned or dried, down to a 15-25% moisture content.
    Wood moisture content should be confirmed by using a wood moisture meter.

    – Are you opening the damper or your stove doors each morning to flush the lingering smoke up out of the flue system?
    In my own situation, opening the stove doors each morning for about 5 to 10 minute before re-loading the stove works well for me.

    I hope bouncing these ideas around has shed some light on solving your creosote issue.

    Burn Save and warn!
    Clay Lamb author of: – Youtube Educational Videos – Professional grade Chimney products – Contractor Coaching Podcast – GM @ American Chimney Sweep Cincinnati,OH

  5. I have a wood-burning fireplace that I have not used in at least six years. I have had it cleaned 3 times since last using it. In the late spring and summer, or when it is raining, the smell of creosote is so horrible that I can’t deal with it. It doesn’t bother anyone else. It isn’t “smokey” smell, it is sharp, acrid chemical creosote smell. Short of ordering specially made doors (2,000 and that still won’t be totally tight) for it or getting the damn fireplace taken out (have no idea how much, brick home), I don’t know what else to do.

  6. Greetings Louey,

    First off, I agree with you, chimney creosote odors stink!! I would have it evaluated by a chimney sweep in your area – I will provide you a chimney sweep finder below. When you find someone you want to ask them if they do PCR (Poultice Creosote Remover) treatments. What’s distributing odor in your house is probably the furnace or the duct work. But you have to remove the odor from the source first and includes the entire chimney flues, the chimney chamber, and so on! I think this would be a much better investment than the glass doors you suggested. Everyone I know who’s has this done has told me they’ve been incredibly satisfied with this removing their problems with creosote odors! (Chimney Sweep Finder by using your Zip Code) (great informational video about PCR)

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