Separation of flue liners

[jfreedman]

Hi all, I'd greatly appreciate any feedback that you can provide.

I have a single brick chimney with two clay flue liners inside of it. One clay liner terminates at the first floor, the other liner terminates at the second floor. The problem is that these two flue liners do not have any separation between them. Currently, they touch. My state's (Massachusetts) building code says:

6001.10 Multiple Flues: When two or more flues are located in the same chimney, masonry wythes shall be built between adjacent flue linings. The masonry wythes shall be at least four inches (602 mm) thick and bonded into the walls of the chimney.

I plan on removing at least one of the clay liners because it's quite badly damaged, and replace it with a stainless steel liner, but that doesn't solve the flue separation. There is physically enough room inside the chimney to shift one of the liners over a few inches and have a masonry wythe between them. However, there is not enough room for the human required to do that. What I mean is that the chimney is fairly tall, and the space is too narrow for a person to squeeze into the chimney to build the masonry separation.

I can't think of a way to build a brick separator without punching many holes in the chimney, which I'd very much like to avoid. Is there a way to meet code that doesn't require building a brick separator? Like something I can drop in or pour in from the roof? Or is there some sort of janky reacher-grabber tool that would let me build up the masonry wall while standing on the roof? Or are there flue liners that don't require masonry separation, even when the code calls for it?

Any suggestions here would be very much appreciated. I don't want to just cover up the issue, but I also want to fix it myself if at all possible.

 

[bholler]

Hi all, I'd greatly appreciate any feedback that you can provide.

I have a single brick chimney with two clay flue liners inside of it. One clay liner terminates at the first floor, the other liner terminates at the second floor. The problem is that these two flue liners do not have any separation between them. Currently, they touch. My state's (Massachusetts) building code says:


I plan on removing at least one of the clay liners because it's quite badly damaged, and replace it with a stainless steel liner, but that doesn't solve the flue separation. There is physically enough room inside the chimney to shift one of the liners over a few inches and have a masonry wythe between them. However, there is not enough room for the human required to do that. What I mean is that the chimney is fairly tall, and the space is too narrow for a person to squeeze into the chimney to build the masonry separation.

I can't think of a way to build a brick separator without punching many holes in the chimney, which I'd very much like to avoid. Is there a way to meet code that doesn't require building a brick separator? Like something I can drop in or pour in from the roof? Or is there some sort of janky reacher-grabber tool that would let me build up the masonry wall while standing on the roof? Or are there flue liners that don't require masonry separation, even when the code calls for it?

Any suggestions here would be very much appreciated. I don't want to just cover up the issue, but I also want to fix it myself if at all possible.

You aren't going to be able to remove one and not the other if they are touching.

 

[jfreedman]

You aren't going to be able to remove one and not the other if they are touching.

I haven't had any issues so far. I've already removed about half of the tiles from one of them. Just by hooking each tile with a rope and pulling them out from the top. Some resisted a bit, but the cement between the tiles gave way without much difficulty. The other stack seems to be unaffected. What issue did you expect that I would run into when trying to remove one?

 

[EbS-P]

What size are the clay tiles and what appliances are they venting? How are you able to observe that they are touching?

 

[bholler]

I haven't had any issues so far. I've already removed about half of the tiles from one of them. Just by hooking each tile with a rope and pulling them out from the top. Some resisted a bit, but the cement between the tiles gave way without much difficulty. The other stack seems to be unaffected. What issue did you expect that I would run into when trying to remove one?

You are only half done chances are at some point you will have to start breaking out tiles

 

[jfreedman]

What size are the clay tiles and what appliances are they venting? How are you able to observe that they are touching?

Tiles are approximately 13" X 8.5" (O.D.). Height of each tile varies. Both stacks are just venting basic wood-burning fireplaces. At some point down the road I might put in wood-burning inserts. Nothing too crazy.

I know that they're touching because the chimney crown is currently removed. I can also see that they're touching from the second floor fireplace.

You are only half done chances are at some point you will have to start breaking out tiles

You could very well be right, but I'm not sure it's relevant to my main problem. Regardless of whether I have to break all the tiles or not and replace both clay liners with SS liners, I still have the masonry separation problem that I'm not sure how to solve.

Removing the flues isn't the problem I'm having. Fitting a masonry wall between the flues isn't a problem either. (There's extra space in the chimney, so I can shift the flue liners a bit.) the problem is there's no good way (that I can think of) to build the wall because the chimney isn't wide enough for a human to go down/up.

 

[bholler]

Tiles are approximately 13" X 8.5" (O.D.). Height of each tile varies. Both stacks are just venting basic wood-burning fireplaces. At some point down the road I might put in wood-burning inserts. Nothing too crazy.

I know that they're touching because the chimney crown is currently removed. I can also see that they're touching from the second floor fireplace.


You could very well be right, but I'm not sure it's relevant to my main problem. Regardless of whether I have to break all the tiles or not and replace both clay liners with SS liners, I still have the masonry separation problem that I'm not sure how to solve.

Removing the flues isn't the problem I'm having. Fitting a masonry wall between the flues isn't a problem either. (There's extra space in the chimney, so I can shift the flue liners a bit.) the problem is there's no good way (that I can think of) to build the wall because the chimney isn't wide enough for a human to go down/up.

I honestly wouldn't worry about the wall at all. The main reason for a wall is to reduce the risk of smoke crossover and protect the other flue from damage in the event of a chimney fire once you put in an insulated stainless liner that risk is eliminated. I will say it doesn't make sense to me to put in a liner for an open fireplace when you plan on installing an insert later though. It is just wasted time and money.

 

[coaly]

Why not use rigid stainless liner that will stay apart where put, and pour in? Search “cast in place”.
Rockford has the products and excellent knowledge of what they sell along with advice. This product?

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[EbS-P]

Just for reference I was a able to install an insert with 25’ of insulated liner for 2k$. Prices now probably have it up to 2400$. And it took me probably 8 hours. Including cleaning and breaking out old damper.

Don’t make more work for yourself. An insulated oval liner 6” equivalent liner would fit without removing the clay.

 

[bholler]

Why not use rigid stainless liner that will stay apart where put, and pour in? Search “cast in place”.
Rockford has the products and excellent knowledge of what they sell along with advice. This product?

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

That is absolutely a good idea. But that is pour in insulation. Cast in place liners are a very different product. Depending upon the size of the masonry chase the cost of filling with pour in may be prohibitively expensive as well

 

[coaly]

That is absolutely a good idea. But that is pour in insulation. Cast in place liners are a very different product. Depending upon the size of the masonry chase the cost of filling with pour in may be prohibitively expensive as well

A few bags of that and my scrap pile, recycling, cat litter, and maybe the barking neighbors dog would be gone.