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  1. #1
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    Default Wood burning chimney liner

    Last year part of my continuing education included a class taught by Jack Pixley regarding inspecting fireplaces. Jack taught us that the bottom of the clay liner can not be left exposed, so I've been calling them out since then. A few days ago I called out the pictured liner. The photo is taken looking up the chimney. Today I received an email from the listing agent which contained the following letter from a mason:

    After a thorough inspection of the chimney flue at xxxxxx address removedxxx I found no glaring deficiencies. I paid particular attention to the area pointed out in the photo which had been taken by others. They seem to think there was some sort of problem with the back side of the first flue placed on top of the smoke chamber. I found just the opposite as the flue had been placed snugly and solidly on top of the smoke chamber. There were no gaps or air spaces between the flue and top of the smoke chamber. The remainder of the fireplace flue appears to be in good condition.
    I sent an email containing the picture to Joe Spoden, the Operations Manager at Jack Pixley Chimney Sweeps and asked him what he thought. I received the following from Joe:

    The liner is not to code. The gap that is visible needs to be addressed. The way that this done is to use a product called chamber tech. It is applied to the back wall of the smoke chamber or side walls of the chamber and smoothed up to the tile. This plugs the hole so that smoke is no longer able to get into the internal chimney structure.
    In our industry we call it "parging" of the smoke chamber. It addresses all areas of concern and brings that part of the chimney to code.
    If you have any further questions please don't hesitate to call or e-mail me I would love to assist if I am able.
    Joe C. Spoden Sr.
    Operations Manager/President
    Jack Pixley Chimney-Sweeps & Masonry
    So I sent of copy of Joe's response to the listing agent and haven't heard anything back. I'm wondering what the rest of you think of the exposed liner.

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  2. #2
    Join Date
    Feb 2009
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    Southern Vancouver Island
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    4,549

    Default Re: Wood burning chimney liner

    You saw a gap, Joe saw it, I see it. We must all be blind.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  3. #3
    Join Date
    Jun 2010
    Location
    Vancouver
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    202

    Default Re: Wood burning chimney liner

    the listing agent was worried about a sale, not the imformation of how it is an easy fix, and how if they handled it properly would not have to worry about it. they were trying to deflict and and all critisms about the home. it was an easy fix and if handled properly would not hurt the sale of the home. Admit it deal with it and move on with business. Yes it could be a serious problem if not handled properly but fixed right it is nuthing more to worry about there.


  4. #4
    Brian Keeler's Avatar
    Brian Keeler Guest

    Default Re: Wood burning chimney liner

    Having been a mason and built quite a few chimneys (in a former life) I believe the "gap" everyone is referring to is actually the bottom edge of the flue liner. When the throat is built (upon which the flue liner is placed), the outside of the chimney (the wythe of brick running parallel with the fireplace profile and furthest away from the firebox) is nominally 4 inches if it is an exterior wall and 8 inches if it is an interior wall (and has framing/combustibles in close proximity). So that exposed bottom edge "hangs in mid air" and the flu liner is supported on the other three sides (minimally). This is the way it has to be done. Setting the flue on/in to the 4 or 8 inch wythe of brick would result in the wall not complying with the 4 or 8 inch wall thickness required by the AHJ in most areas. I was taught to parge the brick wall prior to placing the first flue. While I can't see the "gap" everyone else is referring to I can see the pargetting on the wall. Anyone that has actually placed a flue liner on a throat knows that that first flue is typically built into the chimney/"backfilled" very well to prevent problems later. Even if it weren't, the mortar droppings into the chimney (from running up the shell) would more than fill any voids smoke may seep into. Before I would call out a gap, I would actually want to see one (which would require a scope or having the neck of a giraffe). In my opinion confirming this is not "readily accessible". Besides, I would be more concerned about some of the large corbelling/steps that were built into the throat (they ARE visible). That will tend to contribute to improper draw/smoke entering the living area of the house. I'm quite sure the buyer would be more concerned about that than smoke entering the chimney. Finally, the photo provided seems to indicate the chimney has had some use. Were there any indications (i.e., soot/smoke stains) of improper draw or smoke "leaking into the chimney" (visible in the attic, if accessible)? If not, I may mention during the inspection (and then document in the report) the potential for "improper draw" during certain conditions but I certainly wouldn't freak out about it. Remember, you can't beat a man at his trade. In this case, a picture is nice but it doesn't quite beat being there (or being the one that put it together). I know there's a lot of shoddy work out there these days but the photograph provided doesn't provide enough evidence for me to rant and rave about.


  5. #5
    Join Date
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    Spring City/Surrounding Philadelphia area
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    3,473

    Default Re: Wood burning chimney liner

    I don't see a gap but maybe it's the pic. I do see the bottom exposed edge of the flue tile section that creates a small 90 degree shelf.

    "It takes a big man to cry. It takes an even bigger man to laugh at that man". - Jack Handey

  6. #6
    Join Date
    Jul 2009
    Location
    Indianapolis, IN
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    41

    Default Re: Wood burning chimney liner

    Quote Originally Posted by Nick Ostrowski View Post
    I don't see a gap but maybe it's the pic. I do see the bottom exposed edge of the flue tile section that creates a small 90 degree shelf.
    I believe that is the whole point. The smoke can go outside the liner and into the chimney shell. It is a relatively simple fix as has been suggested. If the whole concept of using a flue liner is to contain the products of combustion, why would you leave the bottom an open path?

    Codes do specify that the liner should be supported on all four sides. The only exception would be a fireplace that is using two flue tiles. In that case the perimiter of the two is expected to be supported, but not the center.

    Ashley Eldridge
    CSIA Director of Education
    ashley@csia.org
    Chimney Safety Institute of America

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  7. #7
    Join Date
    Mar 2007
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    Smile multiple issues

    Brian, I must respectfully disagree with you on a few points.

    First of all, if your rear wythe wall does not have sufficient corbel or ledge to support the rear wall of the flue tile then it is incorrect and that is the problem for the mason. Sure, it may require an additional wythe wall but that is the mason's problem--not the codes'.

    In the photo provided, we see inadequate support on the rear of the bottom flue tile. The shading suggests the presence of a gap but it also means there is great potential for one down the road. Look at all the other mortar joints. They are protruding and appear to be laid with ordinary mortar, such as Type N. All codes require some type of refractory mortars with thin joints struck smooth. These are not.

    As for parging, it is required to make a smooth transition from the throat to flue. This parging is too thin as you can still make out the corbels of the smoke chamber. This smoke chamber also appears to be quite tall, which can be a problem.

    Now, let's examine that all too critical first joint between the bottom flue tile and its supporting smoke chamber. The code expects there to be full perimeter bearing as Ashley stated. That means the edge of the last brick course should be essentially flush with the inner face of that first tile but no more than 33% overhang as discussed by the codes under 'corbelling'. In other words, you cannot rely on parging alone for this joint if the overhang is more than 33% of the flue tile. Also, there should be the requisite refractory mortar (ASTM C-199 or medium duty non-water soluble calcium almuinate refractory cement mixture).

    Attempting to caulk or parge similar overhangs may be the most common field repair using CT2000 but it does not meet the code's intent. The code allows for smoke chamber walls to be 8" solid masonry units unless parged with AT LEAST 2" of refractory mortar or equivalent in which case it can be reduced only to 6". There is your problem Brian--building smoke chamber walls with only one wythe regardless whether interior or exterior chimneys. If you parge the rear wall with 2" of mortar, the flue tile would have to be corbelled out 2" to meet this requirement.

    As for the "mortar droppings" filling the void around the flue tiles, again the code is very specific on this. The code allows for a min. 1/2" gap and max 4" between the flue tile and chimney wall. That means NO backfilling. It is the mason's responsibility to maintain this joint no matter what. Sloppy workmanship and rationalization are no excuse for the code.

    Since this is involving a real estate sale or transfer, NFPA 211 calls for a LeveL II inspection, which requires it only to be "accessible"--not "readily accessible" as under a Level I inspection. 211 also calls for an inspection by video or other means necessary, which would provide the view directly at those joints up close.

    Now, what was this comment you made about not "beating a man at his trade"??? I'm not attacking you personally Brian but making a point. Instead of tradesmen going by "how I was taught" they should buy a copy of the codes (spelled "law") and hopefully take some classes on them. I suggest you click on the F.I.R.E button on this page for the best training in fireplace inspection and codes in the country.

    Keep the fire in the fireplace.

  8. #8
    Join Date
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    Default Re: Wood burning chimney liner

    Quote Originally Posted by Brian Keeler View Post
    Having been a mason and built quite a few chimneys (in a former life) I believe the "gap" everyone is referring to is actually the bottom edge of the flue liner. When the throat is built (upon which the flue liner is placed), the outside of the chimney (the wythe of brick running parallel with the fireplace profile and furthest away from the firebox) is nominally 4 inches if it is an exterior wall and 8 inches if it is an interior wall (and has framing/combustibles in close proximity). So that exposed bottom edge "hangs in mid air" and the flu liner is supported on the other three sides (minimally). This is the way it has to be done. Setting the flue on/in to the 4 or 8 inch wythe of brick would result in the wall not complying with the 4 or 8 inch wall thickness required by the AHJ in most areas. I was taught to parge the brick wall prior to placing the first flue. While I can't see the "gap" everyone else is referring to I can see the pargetting on the wall. Anyone that has actually placed a flue liner on a throat knows that that first flue is typically built into the chimney/"backfilled" very well to prevent problems later. Even if it weren't, the mortar droppings into the chimney (from running up the shell) would more than fill any voids smoke may seep into. Before I would call out a gap, I would actually want to see one (which would require a scope or having the neck of a giraffe). In my opinion confirming this is not "readily accessible". Besides, I would be more concerned about some of the large corbelling/steps that were built into the throat (they ARE visible). That will tend to contribute to improper draw/smoke entering the living area of the house. I'm quite sure the buyer would be more concerned about that than smoke entering the chimney. Finally, the photo provided seems to indicate the chimney has had some use. Were there any indications (i.e., soot/smoke stains) of improper draw or smoke "leaking into the chimney" (visible in the attic, if accessible)? If not, I may mention during the inspection (and then document in the report) the potential for "improper draw" during certain conditions but I certainly wouldn't freak out about it. Remember, you can't beat a man at his trade. In this case, a picture is nice but it doesn't quite beat being there (or being the one that put it together). I know there's a lot of shoddy work out there these days but the photograph provided doesn't provide enough evidence for me to rant and rave about.
    Think your prior life work may need remediation. Lets hope no serious injuries, fires, loss of life or property has occured.

    NFPA 211's most recent edition and the immediate one preceeding it are available for free-on-line viewing at NFPA.org. Hard copies or digital media versions of current and past editions are avalible for purchase at a nominal fee. They may also be available in your local public library's reference section, and/or your local fire inspector/investigator's offices.

    Last edited by H.G. Watson, Sr.; 04-01-2011 at 09:08 AM.

  9. #9
    Brian Keeler's Avatar
    Brian Keeler Guest

    Default Re: Wood burning chimney liner

    Let me clarify: I left the masonry trade in 1983. I could go on and on questioning the barbs and hatchets that have been thrown. I'm not into that (and believe that may require some "remediation"). I guess it comes down to defining some of the terms, such as "supported on four sides". A flue liner built against the brick wall IS supported on that side. Also, when I state something is required by code I try to provide the exact location in the code - including the year. Otherwise, in my opinion, you're just blowing smoke (so to speak).

    To cut to the chase, the first inspection required in this area is when the first flue liner is set (on the throat). I NEVER built a fireplace/chimney without having it inspected. Further, I never had a chimney inspection fail (because I have always taken the time to research and ensure compliance with the current requirements). I will admit that discussions with the inspector(s) were frequent, most times instigated by me, concerning a specific item in the code and changes that had occurred. I am still living in the same area where I built many of the chimneys. I can't remember the last time a house fire in this area was caused by an improperly built chimney. (unless you want to include candles that were left burning that should have been placed in the chimney) I'll keep watching for evidence of defects but with what I have seen I don't have trouble sleeping at night (likely much to the chagrin of some of you). With the chimneys I helped build reaching 27 plus years of age I seriously doubt that will change. I'm not interested in those of you that are using this thread as part of your marketing program. What I'd really like to know is (besides how old the chimney is and how much it has been used in the past) the outcome/what action was taken to address the issue/as a result of the inspection that started this thread?


  10. #10
    Join Date
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    Default Re: Wood burning chimney liner

    Quote Originally Posted by Brian Keeler View Post
    What I'd really like to know is (besides how old the chimney is and how much it has been used in the past) the outcome/what action was taken to address the issue/as a result of the inspection that started this thread?
    The house was built in 1956. I don't know how much the chimney was used in the past...I didn't live there. The buyer's took the advice of the certified sweep over the mason and demanded it be repaired.

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