About Creosote in Chimneys – Part 3: Why You Should Not Remove 3rd Degree Creosote from Tile Liners

In part 1 of this series, we explained the three stages of creosote buildup. In part 2, we explained how to remove creosote.

Now for the case for not removing 3rd degree creosote from tile chimney liners.

In tile-lined chimneys, it’s the exceptional chimney that has good mortar joints.  In fact, if I were to blindly bet ten people $10 that their chimneys have poorly sealed mortar joints and then we investigated with a closed circuit chimney inspection camera, I stand a good chance of making $100.  I might lose one or two $10 bets, but that’s about all.

The problem with having openings in the system is that liquid creosote can and does go through the joints and/or cracks and accumulates outside of the flue tile.  This is a very serious problem because in a chimney fire this creosote ignites as well and becomes a slow-burning creosote fire not contained inside of a liner.  A house fire becomes a much greater possibility.

It is probably best to consider unsafe any chimney that has had 3rd degree creosote in it, especially if there has been a chimney fire.  Frankly, even if servicemen remove as much creosote as possible, the cleaning does not yield as much safety you’d hope for.

In short, it’s probably best to remove the old tiles completely (getting rid of creosote on the outside of the tiles as well) and replace the liner with a new insulated stainless steel liner.  Here’s why.

The reasons there are bad mortar joints or cracks in chimneys are numerous, including:

  • Some masons “work too fast” and don’t think it’s actually important to seal the joints.
  • The wrong mortar is very often used, or dries too quickly and falls out after construction.
  • The earth is always shifting and the stack of tiles moves over time.  This can open mortar joints and sometimes even crack the tiles.  No matter how good the original job may have been, no one can protect against this.
  • Flue tiles that have contained a chimney fire almost always crack.  They protect the home from fire, but the tiles themselves usually break and mortar is demolished.  This is actually to be expected; it’s the exception if it doesn’t happen.

Before the 1970’s wood heating appliances had lower heating efficiencies.  This was partly because the wood was not as fully consumed, but also because a lot more heat went up the chimney.  This combination usually produced 2nd degree creosote, which is manageable.  Today’s wood burning stoves are very well engineered to get more heat from less wood, and houses are tighter than ever.  Chimneys routinely create 3rd degree creosote (because of the lack of combustion air and the low flue gas temperatures.)

This is why you see so much stainless steel chimney lining done these days.  The chimneys of America are undergoing change as they are being properly sized to their appliances, either by upgrade or by repair.  The stainless steel liners are:

  • The right size for whatever appliance they serve.
  • Flexible enough to shift with the earth.
  • Able to withstand chimney fires without breaking.

Installing Chimney LiningOne reason why more people don’t reline is that reline jobs may cost more than people were planning for; another reason is that many folks just don’t understand the need.  It’s going to take a long time to convert America’s chimneys if either insurance companies or building codes don’t speed up the process by insisting that people change over to a stainless steel liner (or not be allowed to burn wood).

29 thoughts on “About Creosote in Chimneys – Part 3: Why You Should Not Remove 3rd Degree Creosote from Tile Liners

  1. Plumbing

    A chimney cleaning schedule can range from once every couple of weeks to no less than once a year. How often you clean the chimney depends on the amount you use your stove, the type of wood you burn, the type of wood-burning unit you have and the way you operate the unit. However, most fireplaces are not used with enough regularity to justify cleaning them every couple weeks. Unless you are using your fireplace as a primary heat source and have wood burning many times a week, once a year is likely to be a more appropriate cleaning schedule.

  2. 44TheFarm

    We’ve got a severe case of grade 3 creosote in our brick fireplace. House was built in the 1860’s, fireplace was added in the 1940’s. Our local chimney sweep says he could put a stainless steel liner in the chimney, but he can’t do anything about the tar in the smoke chamber. Do you know of anything we could do to solve this? Thanks very much for advice.

    1. Dale Howard Post author

      To begin let me say don’t even consider lining your chimney without getting that 3rd degree creosote out of there first. When I was a young sweep I once lined a chimney without getting the combustible out first and the only good part of the story that followed is that somehow the house did not burn to the ground. Do not fail to deal with this before lining, and do plan to get a liner as soon as you have dealt with it!

      There are solutions. The creosote is acid and a base chemical will neutralize it so that it falls off the walls. The questions really are how and what to apply to the walls and how long will it take to get the job done. The direct and blunt approach is to put lye on the creosote. August West Systems TSR (which is lye prepared for this purpose) really does work, but it’s difficult to find someone who will work with it. For example, I would not just because of the risk of chemical burns and noxious fumes in the home.

      A somewhat slower but safer and cleaner approach is CreAway by Saver Systems. It’ll take a couple/few weeks but if you use plenty of it regularly you can reduce the deposits to a brush-able consistency. There’s also a good chemical called ACS but IMO CreAway works a bit better and faster.

      Rotary chain cleaning may also be an option, which is pretty quick. This is a special metal rod and chain system that basically beats the deposits off the wall. This is not a bad option as long as the shiny creosote is hard; if it’s still gummy the chains won’t do a thing. The best approach would be to have it rotary cleaned and then use a chemical cleaner.

      My advice is to call a few sweeps asking if they do rotary cleaning and if they can sell you CreAway or ACS.

  3. Marc

    question…I have a quote to have stage 3 creosote cleaned from flue for $600…this sounds way too high…what is going rate?

    1. Dale Howard Post author

      Hi Marc,

      I’d say, for actual stage 3 creosote, it can be as much as $600 yes. And in some cases even that wouldn’t be enough. I’d save the $600 and put it with some more money to put in a properly sized and insulated stainless steel liner. Better use of $600!

  4. carpenter

    We recently did a job and put a stainless steel liner in for a wood oil furnace. There was massive amounts of creosote and we had to open the side of the interior chimney and mechanically scrape it off the sides to fit liner in chimney and then rebrick the openings. Sweeping did not remove enough to allow passage of the fb ss liner. There was still some creosote left in the chimney. We could not get it all. It is resealed at the top and bottom around Breach pipe. There was no liner at all on this chimney only brick. Should we still be worried about this creosote still on walls of brick behind liner still igniting?

    1. Dale Howard Post author

      If there’s still creosote there, you still have combustibles so I don’t want to be too casual about this. I’ll say this though: if you got most of it off, that’s a big step forward. And if you poured Thermix around it that should keep it from being able to catch fire because the creosote can’t get any air.

      If, however, you did not install Thermix you’ll want to do that anyway. Here’s what I suggest. The heat from the liner is drying out the creosote still in there now, so if you pull the liner out you should be able to get more off this time around just because it’ll be dryer and more easily removed. I suggest chain cleaning (rotary cleaning) to get out most of whatever is left and then re-install your liner with Thermix.

      This is something for which you might do well to hire a professional. I do congratulate you on the effort to remove that existing creosote and that you’re concerned about what you left behind. So said, most homeowners don’t have the equipment for rotary cleaning nor the access to Thermix. At least give hiring a professional sweep (with rotary cleaning equipment) some serious consideration.

  5. Colin Judge

    I have recently been told by a professional chimney cleaner that the stage 3 glazed creosote build-up in my chimney cannot be removed. You stated in an earlier response (to Mark) that you would leave it and install a stainless steel liner.
    Is this safe? Couldn’t the heat from the liner combust the creosote?

    1. Dale Howard Post author

      What I mean by that is that the tiles should be removed altogether, as opposed to cleaning them. “In short, it’s probably best to remove the old tiles completely (getting rid of creosote on the outside of the tiles as well) and replace the liner with a new insulated stainless steel liner. Here’s why…”

      Hope this clears that up! Thanks.

  6. Clint Sunday

    Hello. I’m 16 and I have pretty much been assigned the job of keeping the fire place going, cleaning it, etc. I’ve been asking my dad for the 3rd year to clean it or have a chimney sweep come, and he seems to insist on letting the stupid “creosote logs” that dry the creosote out do their work.. I don’t think the creosote logs are enough, and due to wrapping paper (before I was born) the chimney was relined from a chimney fire. The house didn’t take damage, but still, I need to know how much creosote is too much? I looked up signs of chimney fires, and puffy creosote was listed. From what I can barely see at the bottom of the chimney, it’s not that bad, but right at the bottom there’s some.. Not really PUFFY creosote but it’s not crystals either. What should I do? It has a white/orange color to it…

    1. Dale Howard Post author

      Hi Clint,

      It looks like you may be the next chimney sweep- bottom line, I think you might want to get rods and a brush and clean it yourself. That my not be Plan A, but if your dad isn’t going to be bring in somebody, well… you’re the man.

      How much is too much? You can get eleven different answers to that question, but one thing we know is a lot is too much and nothing is nothing to worry about. It’s the in-between places that get you and you aren’t in a position to make that determination, nor can “some guy on the internet” make that determination for you. The answer is to brush the chimney.

      I suggest a wire brush, not a flat wire. They come in incremental sizes. If you have a fireplace that was relined there’s a good likelihood that it’s a 10″ or 11″ or even 12″ round liner. Nobody has that brush in stock but it can be ordered for you. I suggest fiberglass rods: especially since the rod and the brush I suggested has the same threaded end.

      It’ll cost about the cost of a sweep to buy the equipment. Hope you and your dad can come to agreement about that. You can see what they have at Home Depot; if they have anything it’ll be “homeowner grade” which is pretty lightweight, but probably half the cost of professional equipment. But save yourself the trouble, they don’t have the brush and probably won’t order it either. You’ll have to find it on the web or find a chimney equipment wholesale place. Whatever you do, know how many feet long the chimney is and what diameter it is before you start. Rods are usually five feet long and you want a couple extra feet (eg 25′ chimney? get 30′ of rods)

      You don’t have to go on the roof and in your case I suggest you don’t; sweep from underneath ie from the hearth. The brush can be crammed through the damper, just shove hard. Brushing itself is pretty straightforward, just push the brush up and down several times, adding sections of rod as you go along. Dust control: make sure there’s a powerful updraft in the chimney when you do it; I suggest get the house real warm first and do it on a real cold day- whatever it takes to make sure the dust goes UP the chimney. Don not, repeat: do not, proceed if you feel cold air whooshing down the flue before you begin. Wear a respirator. Use drop-cloths in front of the fireplace.

      A bunch of stuff will fall through the damper and a bunch will fall behind the damper. Use a shop vac and get the stuff from behind the damper too. It’s a pretty dirty job but you can handle it. When you are done careful how you walk across the carpet, take the stuff outside and go get a shower.

      And think how much smarter you’re going to be after the first time. You’ll only make a mess once :-) and you’ll already be semi-pro.

      Good luck, chimney sweep!

  7. Chris LaMarr

    A lot of what I have been reading about creosote deals specifically about build up inside a clay lined or masonry chimney. I have a question about a stainless chimneys. Last year I removed the old masonry chimney from my house and installed a new stainless chimney from Simpson (Duratec brand). I am burning a Charmaster forced air furnace (wood only, no oil burner). We have been burning now for about 6-7 weeks and I am starting to see some creosote build up. I removed the flue pipes from the back of the stove and found stage 2 creosote “chips” in the elbows and in the clean out lid. I am also starting to see some stage 3 tar on the pipes, not what I would say is alot, but it is there none-the-less. My question is this, should a creosote fire ignite, how do the new stainless double wall insulated pipes handle it compared to the old clay flues? Also, how do the stainless (Duratec) chimneys handle rotary cleanings and chemical cleanings? I grew up burning a fireplace insert, and we never really thought about the chimney, but now that I have my own house and my own kids, I think about that chimney every day there’s a fire in the furnace.

    Thanks in Advance!!


  8. Raelyn


    We have a fire place insert with a ss liner. We put the insert in 18 months ago. We didn’t get it cleaned this year. My husband said he would but never got around to it. Tonight I noticed the familiar creosote smell coming from the stove. I told my husband and he thinks he can clean the chimney himself with a brush and a rope tied to both ends, me at the bottom of the rope. Personally I think this is about the dumbest thing I’ve ever heard. I grew up with wood stoves and we always got the chimneys professionally cleaned. With the smell I’m thinking we have a ton of stage 1 possibly stage 2 creosote. We should have a professional cleaner come in? I can’t imagine getting the creosote off with a brush and a rope. Ugh.

    1. High's Chimney Post author

      I’d think you’d want to get it done professionally, but then I’m in that business :-) Fact is that you can run a brush up and down a chimney using ropes. Be sure to wear respirators, and stop right away if the dust isn’t drifting up the chimney; a houseful of soot makes for a bad day.

      The smell may or may not be anything special. If it’s 3rd degree creosote and thick it could be very difficult to get off. First or second degree should come off OK though.

      Cleaning a chimney is a nasty job and that’s why people hire it out (that and the knowledge a sweep might have to recognize a problem you might not see) but the work itself you can do if you’re up for it. Like many things in life, you *can* do it, but do you really want to? I’m sorry you have to be involved since it’s not your kind of adventure.

      Good luck, chimney sweep lady! It might even be fun, who knows?

    1. High's Chimney Service Inc.

      Jim, while that certainly removes stage three, I advise against it heartily. Just don’t- really. The whole purpose of a liner is to protect the home from house fires and chimney fires damage liners. After they crack the first time, they open up enough for liquid creosote to get on the outside of the liners and in subsequent fires that outside creosote can/will burn. And that’s how house fires happen.

      And I’m not over selling here either. When sweeps remove tiles to replace them with a stainless steel liner they regularly find creosote on the outside of the tile. Plus my personal experience: when I was much younger and dumber I set a few chimneys on fire and in two cases I nearly burned the houses down. I strongly advise against this practice!

      Be careful, and good luck.

  9. Greg Allison

    At what temperature does stage 3 creosote ignite ? The reason I am asking is I have stage 3 all around my flu opening and above. I have been using anti creosote spray and I dont think I am getting my fire hot enough for the spray to work. I am afraid of igniting the creosote.

    Thanks a bunch

    1. High's Chimney Service Inc.

      That’s a tricky question. Different sticky messes ignite at different temperatures, and -full disclosure- I used to know the range but have since forgotten. Suffice to say it’s not all that high. Like 400 degrees or something.

      I have a couple suggestions for you. One is to switch from ACS to Creaway. It’s better suited for your situation. The other is if you want to do something more quickly.

      The tar (ie cresote) is acid and you can neutralize it relatively quickly with a base (which is part of the action in Creaway) The problem is that strong bases chemicals are also inconvenient to dangerous. Red Devil lye (and probably Liquid Plumber) comes to mind. You can mix it up, but then you have to apply it. It’s a messy affair where you can have nasty black liquid dripping on your hearth etc. Also you can get chemical burns doing it. If you have kids around it’s all the worse. I’m making a terrible case AGAINST doing this, but I’m telling you about it anyway because it’s so effective and fast. Whatever you do though, switch to Creaway.

      In any event, yes that stuff will ignite at a fairly low temperature and it can attain a very high temperature once it gets going. I’m glad you’re concerned enough to do something about it.

      Good luck!

      1. Greg Allison

        Thanks for your help, greatly appreciated. Can you tell me how to use the Red Devil Lye, Liquid Plummer or any thing of this sort ? I have a wood stove not a fireplace. Have a cleanout at the bottom of my chimney/flu. The stove and bottom of flu is in a basement.
        My flu is clay tile built in 1980. I am really ready to try just about anything.
        If you can tell me how to mix and use these chems it would be great !…………and tell me the hazzards too.
        Thanks again, Greg

        1. High's Chimney Service Inc.

          How to use the chemicals: in a word- carefully!

          The hazard is that lye is dangerous. If it gets on your skin you’re burned. If in your eyes, maybe you’re blind. It’s pretty nasty stuff really. Another hazard is that it will likely make a mess that may be difficult (or impossible) to clean up, so don’t let it get on your hearth.

          So how to apply? No good way since it’s probably not a great idea to start with :-) but here’s how I did it. I took an undersized chimney brush and wrapped it with a towel so I had a big swab. I mixed a can of lye in a 5 gallon bucket of warm water and then swabbed down the chimney adding chimney rods as I went. (I do understand that you probably don’t have this equipment)

          The immediate result was that it made a terrible black wet mess at the bottom. The chimney did not immediately come “clean”. But when I returned some months later the flue was as clean as the day it was built. The stuff dried and fell off under it’s own weight with some time.

          I did this only once or twice because of the safety issues and the likelihood that I’d mess up somebody’s hearth permanently, but it was very effective indeed. If you have the heart for it and can rig the swab it will work. Just remember the key work here- carefully. Lye is a no-foolin’-around chemical.

          BTW, you could also call a chimney sweep and tell them you want TSR applied. TSR has the advantage of being thicker so not as runny but it’s only available to chimney professionals. It may take several calls to get someone who knows what it is AND is willing to take the job.

          Good luck!

  10. Mike Auger

    I have a thin black glaze on my clay chimney liner, less then 1/8 inch. I would like to get this glaze off before I install my new 6 inch stainless steel liner but I want to do it fast.
    You mentioned using a stainless steel cable, using chains and using a base chemical. What is the fastest way?
    Or can I but an insulation blanket around my liner and leave the black glaze?
    Or should I buy a snap wrap type of insulation and put that around my stainless steel liner and leave the black glaze?

    1. High's Chimney Service Inc.

      Only the chains/cable whip can give instantaneous results. They don’t do as thorough a job as chemicals, but those take time. In the balance I’d 1) clean it with chains/whips 2) burn with a lot of Creaway for a couple days and then put the insulated liner in. You’ll get 90+% with the mechanical cleaning, and Creaway will bring down most of the rest of it over time (it’ll be dusty and fall to the smoke chamber or on top of the stove)

      Good luck!

    1. High's Chimney Service Inc.

      Yes. There is a very effective new product just introduced to the market which will take care of the problem. But first you have to get the brush out of the chimney :-)

      Professional sweeps have hooks that can reach down through the brush (on a rods) and pull it back up. A poor man’s version of that, and the way I did it the first time it ever happened to me back in the 80s, is a pair of pliers duct-taped securely to a rod. Shove the pliers through the brush, and when they open up underneath the brush pull it back up.

      The gist of the article is that there are lots of reasons why you shouldn’t even bother to remove 3rd degree creosote. Please consider that information carefully. But if you are very comfortable that the tiles are in good condition, there is a new method for removing third degree creosote is Saver System’s Poultice Creosote Remover (PCR). The before and after picture are astounding and it works quickly (just a few days)

      It is very new so when you call a sweep to tell him you want your chimney treated he will probably have to order it. There’s a special applicator system which he’ll have to get as well. This won’t be cheap, but it will really fix the problem. Once your chimney is back in great shape be careful not to develop 3rd Degree again- burn hotter fires, use ACS or Creaway as you burn, get a liner, or whatever is appropriate for your situation (lots of blog articles here on these subjects)

      Sweeps luck to you!

  11. Barbara Eska

    Just had an estimate of $650 to remove Stage 3 creosote from a stainless steel chimney liner
    after 1 year of use. How could this get so bad in 1 year? He took pictures and I told him I’d have to think about it. Never had a fireplace before so I may have burned logs that weren’t completely dry sometimes. Know nothing about wood burning. I did buy an insert.
    Is there anything I could do myself. I am told they don’t sell Stage 3 cleaner from Northland Express any longer to regular customers. Is it really that expensive?

    1. High's Chimney Service Inc.

      Hi Barbara,

      I understand the question. It is true that that chemical is fading from the market. It’s basically lye and the liability, not to mention it is shipped as hazardous material. On top of being dangerous, it’s messy, hard to apply, and slow working.

      This year a new chemical came out (PCR) which addresses all those problems, but it’s pretty expensive. It is sold to the trade only, so it is not available to the general public, at least that I’m aware of. The process requires two trips, once to apply and the next day to clean up the modified creosote that falls off and brush the rest. It is very effective.

      Between the cost of materials and the fact that it takes two trips, that price isn’t out of line. I’ve heard it costing as low as $550 and as much as $800.

      If you bought an insert, that stuff has to go, because it’s only going to get worse with the stove. I would be willing to bet good money you will have a very substantial chimney fire from the info you gave here.

      My suggestion? The insert is supposed have a properly sized liner anyway, why not have the tiles removed and then run the new liner straight to the stove? Since you are looking at a high-priced cleaning that will probably just need to be done again next year, your cost factor is mitigated by “the wasted money” you’ll be spending anyway. In my opinion this is the right way to go.

      I know nobody expects or likes the surprise expense of being told to get a stainless steel liner, but it really does pay. And with a liner you get something lasting for your money vs an annual-high-priced-cleaning. Think about it anyway.

      Good luck!

  12. Mike

    I have a very large stone chimney with a permanent steel cap over it. With only a foot or two of clearance, I’m wondering how to get the rods in there. I suppose I could use ropes with a person at both ends, but it seems the person at the bottom will be the victim of a soot/creosote shower. Is there an easier way to deal with this?

    1. High's Chimney Service Inc.

      Interesting you should mention this. I remember the day I was standing in a walk-in fireplace with black crap falling on me like rain saying to myself “What am I doing here? I am a man, not an animal.” So said, I was being paid to do what needed to be done. You see where this is going…

      Yep. If you can’t get the top off and get rods down there, you sweep from the bottom (or use a rope as you mentioned.) If it’s a normal sized fireplace you may want to just stay out of the way of the falling tar and soot, brushing from just in front of the fireplace ie let it land right in front of you (careful to do it when there’s a strong updraft so you don’t fill the house with soot.) But more than half will land on the smoke-shelf and you pretty much have to crawl in on your hands and knees and sweep it all off by hand.

      No matter how you cut it, it’s a lousy job. And that’s why people hire chimney sweeps- nothing anyone couldn’t do themselves, but not something many want to do themselves. You sound like a hearth soul; just git ‘er done and take a shower right after :-)

      Good luck; you can do this!


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