# Interlocking clay liners & metal bands



## fjn (Aug 17, 2011)

I have always considered flat ends of clay liners to leave a whole lot to be desired. There are a few companies in U.S. that make interlocking flues (only in round to my knowledge ) The U.K. has quite a few offerings in both round,square and rectangular.


While searching,I ran across this metal band.It seems possible it can enhance the liner connection. I did ask one large clay producer why they did not offer their square liners in interlocking,never did get an answer..

http://www.google.com/patents/US4878326


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## dom-mas (Nov 26, 2011)

I did a chimney rebuild this fall for an indoor wood furnace. The flue liner was a lightwieght concrete with metal bands holding it together. I couldn't find that same flueliner anywhere and the band where rusted away to almost nothing. I used a few hose clamps joined together and some galvanised sheet steel wrapped around them so i could get this thing rebuild (refractory between the units). I have no doubts it will last the 3o years at least that the original did


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## dom-mas (Nov 26, 2011)

The way i build chimneys though the fue liner shouldn't be able to move anyway. I certainly don't fill in the void between flueliner and chimney but i do let mortar squeeze out in enough spots to hold it securely.


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## fjn (Aug 17, 2011)

dom-mas said:


> The way i build chimneys though the fue liner shouldn't be able to move anyway. I certainly don't fill in the void between flueliner and chimney but i do let mortar squeeze out in enough spots to hold it securely.





I hear you on that,regarding securing flues. Each mason probably has their favorite method. Mine is to use 4" HDG wire,I place one piece on each side of flue,leaving about 3/8" clearance.


As far as the metal banding,I think it goes without saying,stainless would have the best life cycle.

Aside from that,a tongue and grove end would provide the most positive connection. Why it is only offered in round is a good question.


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## stuart45 (Oct 7, 2009)

I've only ever seen and used spigot and socket on clay liners. Used to fill with mortar but nowadays a cement/vermiculite mix is used for insulation.


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## wazez (Oct 25, 2008)

A little bit off topic but if your building chimneys for wood stoves this is the only way to go imo. http://www.clickstoves.com/TOPEKA3/CHIMNEY_SYSTEMS.html


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## Eddie's Masonry (Feb 7, 2015)

*Clay Liners*

I have masonry business and we build a lot of chimneys in the Syracuse,NY Area. In my area I can't find interlocked liners but there are circle,square and rectangular liners in the area. When we build new chimney with liners or repair we put mortar in between liners for a good structural bond.


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## fjn (Aug 17, 2011)

wazez said:


> A little bit off topic but if your building chimneys for wood stoves this is the only way to go imo. http://www.clickstoves.com/TOPEKA3/CHIMNEY_SYSTEMS.html





Wazez; Thank you for the heads up.You learn something new every day. Know exactly where Topeka stove is,bought many horses right across the street at the annual spring and fall draft horse sale,never stopped in to the store though. Makes sense they sell a bunch of wood burning stuff with all the Amish in the area.


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## fjn (Aug 17, 2011)

Here is a picture of what I mean regarding a interlocking clay flue.


http://hepworthterracotta.wavin.com...4445264098&FOLDER<>folder_id=2534374305532425



The connection would be way more secure than what we normally see in a flush end so prevalent in U.S.


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## wazez (Oct 25, 2008)

fjn said:


> Wazez; Thank you for the heads up.You learn something new every day. Know exactly where Topeka stove is,bought many horses right across the street at the annual spring and fall draft horse sale,never stopped in to the store though. Makes sense they sell a bunch of wood burning stuff with all the Amish in the area.


Yeah ya need to stop in sometime. Those guys are very knowledgeable in woodstoves and chimneys.


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## dom-mas (Nov 26, 2011)

wazez said:


> A little bit off topic but if your building chimneys for wood stoves this is the only way to go imo. http://www.clickstoves.com/TOPEKA3/CHIMNEY_SYSTEMS.html


that is the exact product that had the metal straps around each joint. Not sure if it was the same manufacturer but seemed the exact same 

I actually would say that it was performing terribly. The house was built in '82 and could fit my hand through some parts of the chimney. The inner liner was deteriorated down to the cap, i had to replace that section and ended up going with clay since i couldn't find the product anywhere. I filled the void with a vermiculite portland mix. Hopefully it serves well. The fireplace store that originally sold the product went out of business about 7 years ago and none of the normal masonry or fireplace centers I deal with had any knowledge about it

There was more creosote on that liner than on any other liner I've ever seen although since the wood furnace was the main heating system that is sort of to be expected. But I do see wood stoves vented into masonry chimneys that they aren't as bad The inner surface seemed rough, something more likely to have creosote build up than something smooth like clay. I know the chimney has regular cleaning and maintenance because the son of the owner is a firefighter and checks it twice a year and cleans it at least once a year.

I was not impressed at all, i would never suggest that product after seeing how it lasted after only 30 odd years


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## Rockmonster (Nov 15, 2007)

I've seen them, perhaps they never really caught on because the nature of terra cotta tiles, being quite imperfect....

Maybe because the reality is that too few stacks are plumb......

I've always parged the flue connections..... admittedly, I don't see that a lot.....but flue gases and acidic rain can eat through thin mortar joints pretty quickly in our area.....

I remember reading about some flue tiles being made out of some kind of pumice many years ago, but I've never seen them.


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## fjn (Aug 17, 2011)

Many moons ago,I built a fireplace and chimney for a guy that had real deep pockets. He asked me what I thought would be the best flue liner I could think of. I told him,if your checkbook can handle it,I will line it with fire brick. He said fine,have at it.:thumbsup:


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## CJKarl (Nov 21, 2006)

I built one here in CT. But the architect was from San Francisco. Grouted the entire chimney solid. That was 20 some years ago, I would love to see how it's held up.


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## cdkyle (Jul 12, 2009)

fjn said:


> Many moons ago,I built a fireplace and chimney for a guy that had real deep pockets. He asked me what I thought would be the best flue liner I could think of. I told him,if your checkbook can handle it,I will line it with fire brick. He said fine,have at it.:thumbsup:


I'm assuming you meant you wrapped the outside of the flue with firebrick. This would be the ultimate scenario. We always wrapped the flue liner with a wyth of brick, parged the joints, and always filled the void/s with masonry (brick &/or block.)
Back in the day, years ago, if we had a situation where the flue was going to be anywhere close to wood or combustibles, my dad would stop by the lumber yard and get those asbestos shingles to cover the wood.
The inter-locking flue tiles make a lot of sense. The steel band, not so much.


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## dom-mas (Nov 26, 2011)

why do people fill the void? It's just the worst, allowing all that material to exist and hold moisture. Allowing all that heat to transfer to the surrounding masonry.


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## cdkyle (Jul 12, 2009)

dom-mas said:


> why do people fill the void? It's just the worst, allowing all that material to exist and hold moisture. Allowing all that heat to transfer to the surrounding masonry.


Seriously? Apparently we differ in opinion. School me.


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## Eddie's Masonry (Feb 7, 2015)

The hose clamps joined together with some galvanized sheet steel wrapped around them it will give you a strong structure.


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## Eddie's Masonry (Feb 7, 2015)

In some cases we use mortar to bond the liners but we use a fire mortar that can stand up against the heat.


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## Eddie's Masonry (Feb 7, 2015)

Fire brick will work as long as you used fire mortar.


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## dom-mas (Nov 26, 2011)

cdkyle said:


> Seriously? Apparently we differ in opinion. School me.


Like I said, there;s mor mass to hold moisture, nowhere for moisture or water to travel except through the chimney to the place of less heat and humidity...outdoors. 

Also there is more heat that can travel thruogh. the fue liner is there to isolate the surrounding masonry from the fue gases...and the heat. Fill the voids and that's gone. Even if youleave only an inch or even 1/2" it's better than filling the void completely


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## fjn (Aug 17, 2011)

Eddie's Masonry said:


> Fire brick will work as long as you used fire mortar.





That is the method I mentioned I did. Fire brick,fire clay mortar taking the place of a clay liner.


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## fjn (Aug 17, 2011)

As others mentioned,the flue should have the ability to expand both vertically and horizontally. Packing the flue solid with mortar restricts that movement causing flue and or brick cracking.

This article stresses those details along with stabilizing the flue with joint wire. That is the method I have adopted.



http://www.maconline.org/tech/construction/chimney/chimney.html


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## heavyc (Jul 2, 2013)

dom-mas said:


> why do people fill the void? It's just the worst, allowing all that material to exist and hold moisture. Allowing all that heat to transfer to the surrounding masonry.


If the firebox, smoke chamber and flues are positioned/ installed correctly there shouldn't be any heat going up the chimney? Also where is the moisture coming from ? Smoke, gasses and occasionally sparks are what goes up the chimney? We always turn flues like a very mild cork screw if you will. The best drawing fire places are the ones you look up the chimney or down and don't see day light.
As stated above we always slip joint and seal each flue liner connection and parge with our fire clay mixture. This is code in our area. So the flexing and moving of flues through expansion and contraction theory would mean that every connection would separate? 
We fire bond our brick around the flues also. As I've said before we also stay back as others about an inch to inch and half and encase the flues in mortar. Almost 70 years now same method in up state N.Y. (Niagara Falls) and now by the grace of God in the sandhills of N.C. No call backs or flue replacements to date?
I recall all the masons from California use similar techniques? In reference to encasing flues?


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## dom-mas (Nov 26, 2011)

No heat going up a chimney??? The elusive 100% efficient fireplace...so you're the guy who did it huh? The moisture comes from the warm moist air inside, compared with the cold dry air outside. The moisture also comes from the elements. It's a big piece of masonry stuck up in the sky


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## heavyc (Jul 2, 2013)

I'm stating that there isn't enough heat going up flues to move them. Next time your on a roof and a fireplace is in use you tell me how much heat comes out. I guarantee you'd rather have gloves on than depend on that lost heat up a chimney to keep your hands warm.
Now for your accusation: I didn't print one claim to a 100% efficient fireplace did I? Glad I got away from the arrogant attitudes I so frequently encountered on the other side of the peace bridge. Kinda disappointed to have kin in Toronto. But they are blood so we all let the attitude slide.


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## dom-mas (Nov 26, 2011)

heavyc said:


> If the firebox, smoke chamber and flues are positioned/ installed correctly there shouldn't be any heat going up the chimney?


This looks like that claim to me

I'm not talking about the heat moving the liners, I'm talking about the heat getting into the mass and causing premature wear


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## heavyc (Jul 2, 2013)

Okay if we're gonna literally dissect that as 100%. I'll recant that to not very much heat going up the chimney. My French is a little rusty or I'd restate it in that too so you can sleep better tonight.


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## heavyc (Jul 2, 2013)

dom-mas said:


> No heat going up a chimney??? The elusive 100% efficient fireplace...so you're the guy who did it huh? The moisture comes from the warm moist air inside, compared with the cold dry air outside. The moisture also comes from the elements. It's a big piece of masonry stuck up in the sky


How is heated air moistened? Anyone familiar with wood heating per say a air tight wood heater usually places a heat resistant vessel with water in it on top of the heater to keep moisture in the mix. Kinda like humid heat is warmer than a low humidity dry heat. Never heard of a fire place creating moisture?


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## dom-mas (Nov 26, 2011)

I'm not talking about heated air, I'm talking about the hot moist air from inside the house. I'm also not talking about wood stoves, I don't think CDkyles post was about wood stoves, just chimneys in general.. I'm talking about the typical chimney for a fireplace on a typical home built between 1940-1980ish. These are the typical chimneys on homes that I see and the ones that I see others post here most commonly. Warm moist indoor air is constantly going up these chimneys and the air condenses when it hits outdoor temps, loading that piece of masonry with more moisture than is typical 

Add to that typically poor chimney maintenance and you get crowns that are cracked, open joints, a cap that has an over hang of 2" rather than 1' like a roof overhang, old caulking and f;ashing that gets looked at every 15-25 years when the roof is getting done and what are you left with? A structure that gets more weather than typical and increased freeze thaw action. If you fill the void you get increased mass to hold water and increased thermal bridging causing premature decay of the chimney.

What do you gain by filling the void? A more rigid chimney? Chimneys have flue runs every 1-2' so there's lots of inner buttressing, rigidity isn't a problem. You definitely get a chimney that is more difficult to take a part when it needs rebuilding, making it especially more difficult to stop. What else do you gain? Ok that flue isn't going anywhere, but it isn't going anywhere with an air space and occasional points of contact. 

Any other benefit??


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## JBM (Mar 31, 2011)

Im not a fan of filling the chimney. To much mass with little reward.


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## superseal (Feb 4, 2009)

JBM said:


> Im not a fan of filling the chimney. To much mass with little reward.


Especially with garbage fill... And yes, I'm pretty sure "much" heat goes up chimneys as I like to take my gloves off :laughing: 

Don't forget about wet wood as well guys when it comes to flue moisture...heavy creosote is your indicator.


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## superseal (Feb 4, 2009)

I often suggested venting block/stucco chimneys with 2 x 8 brick vents positioned strategically to allow air flow to increase internal drying. With all the freeze/thaw issue in these parts, a lot of the bigger mass stacks seem to suffer.


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## heavyc (Jul 2, 2013)

Let me see if I've got this? Fireplaces are basically a waste of money as in they need maintenance and rebuilding frequently? Also your wasting time resources and money on an inefficient heating means? Good selling points for future prospective buyers. Maybe I'm missing the intended installation of a fireplace? Might be useful as a conversation piece?


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## dom-mas (Nov 26, 2011)

Basically. 90% of fireplace are heat losses, good for little more than aesthetics...but people spend a lot of money on aesthetics. Yes there are better built fireplaces ... rumfords and the rumford hybrid Orton but most chimneys that I see are attached to poorly construct holes in the house called fireplaces. If you want to heat your house with wood go with a wood stove, wood furnace or a masonry heater. Even rumfords and Ortons are lucky if they have better than 50% efficiency. 

And to believe that most folks are going to climb up on their roof and inspect their chimney every 5 years or better is just a pipe dream. Chimneys take more abuse than any other masonry on a house and are the most neglected...adding more mass isn't helping any, it just adds to the repair bill later..or sooner


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## stuart45 (Oct 7, 2009)

This is an interesting thread for me as flue liners only became part of the Building Regs in 1965 here. Before that the brick flues were normally parged. Until recent years the gap was filled with mortar,but now the regs require the gap to be filled with an insulating mix such as vermiculite/OPC. Flue liner joints should be acid resistant compound. The theory of the filling was to stabilise the liners when the flue was swept. 
This does not mean that this is the best method as it's been said that the methods of chimney construction in the UK have been based on primitive witchcraft compared to the rest of mainland Europe.


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## fjn (Aug 17, 2011)

Upon doing a tad more digging,it appears the term for interlocking flues in Europe is rebated. This company has quite the offering.


http://www.heidelbergcement.com/NR/...E0C249178/0/Red_bank_concrete_flue_liners.pdf


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## dom-mas (Nov 26, 2011)

Heidleberg was the only company i could find that supplied those concrete flue liners but my supply company had no interest in bringing just one in, and certainly not in the time frame I needed


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## fjn (Aug 17, 2011)

dom-mas said:


> Heidleberg was the only company i could find that supplied those concrete flue liners but my supply company had no interest in bringing just one in, and certainly not in the time frame I needed





:thumbsup:


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## fjn (Aug 17, 2011)

This article is sorta,kinda interesting.




http://www.masonryconstruction.com/Images/Clay Flue Lineup_tcm68-1375715.pdf


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