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).

15 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.

    Reply
  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.

    Reply
    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.

      Reply
  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?

    Reply
    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!

      Reply
  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?

    Reply
    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.

      Reply
  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?

    Reply
    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.

      Reply
  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…

    Reply
    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!

      Reply
  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!!

    Chris

    Reply
  8. Raelyn

    Hi,

    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.

    Reply
    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?

      Reply

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