Wood Burning Fireplace Relining and Enhancements

1910Home · Jan 14, 2019

New member and first post. I have been working towards relining my chimney for several months now and was excited to find this site today. I'll dig right in...

We have a historic home built in 1910 with an original wood burning brick fireplace that was converted to gas about 20 years ago, and we are looking to go back to wood burning without an insert. Had several inspections done on it a few years back to learn that most of the mortar liner has warn off the inside of the flue. Received quotes ranging from $12k to $18k to reline using various methods as it is a double flue liner. Being a capable DIYer, I decided I could tack it myself.

The details: Fireplace opening is 44" wide by 25" high (1100 in/sq.) and we are using two 7.5" square, flexible 316Ti liners (112.5 in.sq. area) running 23' to the top of the Chimney. Bottom plates will be mesh and using two top-sealing dampers inside a dual-flue cap.

Looking for some some additional guidance and wisdom for a few questions I have found mixed answers to on all the "pro" websites:

#1 - I am in the process of removing several rows of brick where the back wall juts out to the smoke shelf so that I can feed the liners up into the flue. I found about 4 inches of sand and debris resting on the smoke shelf, even after the fireplace was cleaned twice. I believe the issue was that the smoke shelf was so deep that it was hard for the chimney sweeps to get a vacuum up into the smoke shelf area due to a narrow opening. Does a fireplace need a smoke shelf? If so, how large should the opening be from the Fire Box to the Smoke Chamber? Same ratio as the flue to fireplace opening? Here is a photo for visual reference, shown after I already removed roughly 4" of horizontally stacked brick at the top of the back wall.

#2 - I am going with a poured insulation and was planning on trimming the liners just above the chimney and then using Type N Mortar to seal the top creating a slight dome. Would that be acceptable or do I need to use refractory mortar up there as well?

Here are a few more photos for reference.

bholler · Jan 14, 2019

First off fireplaces running on 2 liners usually don't worry well at all. It may work but it is allot of time and money to spend on something that probably won't work right. No a fireplace does not need a smoke shelf but getting rid of it would mean a complete firebox and smoke chamber rebuild. And no you can't mortar the top of the liners fast they need to be able to expand and contact.

maple1 · Jan 14, 2019

You're not doing this for heat - are you?

If anything, it will cost more heat than it will give.

1910Home · Jan 14, 2019

bholler said:
First off fireplaces running on 2 liners usually don't worry well at all. It may work but it is allot of time and money to spend on something that probably won't work right. No a fireplace does not need a smoke shelf but getting rid of it would mean a complete firebox and smoke chamber rebuild. And no you can't mortar the top of the liners fast they need to be able to expand and contact.

Thanks for the reply! Unfortunately, we tried to figure out a way to run 1 liner cost effectively while keeping the fireplace opening original without luck. Due to the original design of our double-flue chimney we had to go to 2 liners. A question about the mortar on top; we are using Everguard pour-in vermiculite insulation, doesn't that work kind of like cement/mortar and will already limit expansion of the stainless liner?

I have to remove a good portion of the smoke shelf to get the liners up into the flue, was just wondering if I totally rebuild what I remove or simply clean it up with refractory mortar.

maple1 said:
You're not doing this for heat - are you?

If anything, it will cost more heat than it will give.

This is not a main heat source for our home. We live in a pretty moderate climate where 50 degrees is pretty cold. More for the ambiance of having a fire burning in our living room while maintaining a more historically accurate fireplace presentation, which is why we are not interested in adding an insert.

bholler · Jan 14, 2019

1910Home said:
Thanks for the reply! Unfortunately, we tried to figure out a way to run 1 liner cost effectively while keeping the fireplace opening original without luck. Due to the original design of our double-flue chimney we had to go to 2 liners. A question about the mortar on top; we are using Everguard pour-in vermiculite insulation, doesn't that work kind of like cement/mortar and will already limit expansion of the stainless liner?

I have to remove a good portion of the smoke shelf to get the liners up into the flue, was just wondering if I totally rebuild what I remove or simply clean it up with refractory mortar.

This is not a main heat source for our home. We live in a pretty moderate climate where 50 degrees is pretty cold. More for the ambiance of having a fire burning in our living room while maintaining a more historically accurate fireplace presentation, which is why we are not interested in adding an insert.

No everguard stays soft enough to allow for expansion.

1910Home · Jan 14, 2019

bholler said:
No everguard stays soft enough to allow for expansion.

That is good to know. What would be a proper way to secure the two liners at the top? Is a metal top place best?

Would it be possible to create some type of expansion gasket or join around the liners between a mortar top cap?

bholler · Jan 14, 2019

1910Home said:
That is good to know. What would be a proper way to secure the two liners at the top? Is a metal top place best?

Would it be possible to create some type of expansion gasket or join around the liners between a mortar top cap?

Yes the top plates that are part of the liner system. But again the majority of double flue fireplaces I see do not work. I do not think this is a good plan.

1910Home · Jan 15, 2019

bholler said:
Yes the top plates that are part of the liner system. But again the majority of double flue fireplaces I see do not work. I do not think this is a good plan.

I am kind of stuck now.

We were having an issue with getting a single liner to support the size of the fireplace opening without a drastic downsize. While in a technical support call with the company that we bought our liners from, which seems to be one of the bigger suppliers, they said running two liners would work as it got us to the usable are we needed.

I now am sitting on two custom 24’ long square liners and all the components to go with them.

Not sure what to do now. Did I just waste $3k?

bholler · Jan 15, 2019

1910Home said:
I am kind of stuck now.

We were having an issue with getting a single liner to support the size of the fireplace opening without a drastic downsize. While in a technical support call with the company that we bought our liners from, which seems to be one of the bigger suppliers, they said running two liners would work as it got us to the usable are we needed.

I now am sitting on two custom 24’ long square liners and all the components to go with them.

Not sure what to do now. Did I just waste $3k?

It might work. I have seen some work and since you have the liners already you might as well try it

1910Home · Jan 15, 2019

bholler said:
It might work. I have seen some work and since you have the liners already you might as well try it

Than you @bholler for the continued feedback! Believe that is what I will do and see what the result is.

With that, I am back to my original question. Is there a formula, like figuring flue size, for the passage needed between the fire box and the smoke chamber?

Should I just leave out the brick rows I remove and clean things up with refractory cement, or put back some of the rows?

bholler · Jan 15, 2019

1910Home said:
Than you @bholler for the continued feedback! Believe that is what I will do and see what the result is.

With that, I am back to my original question. Is there a formula, like figuring flue size, for the passage needed between the fire box and the smoke chamber?

Should I just leave out the brick rows I remove and clean things up with refractory cement, or put back some of the rows?

There is allot that goes into the design of the throught of a fireplace.

jetsam · Jan 15, 2019

If you finish up and the fireplaces don't work, it's probably because there's not enough flue volume for the opening.

In this case you can reduce the fireplace opening (permanently with brick, or temporarily with fireplace doors) until the opening matches the flue better.

If both liners are 7.5"x7.5", that's 56.25"², so a fireplace opening of 3.9sf would be about what to shoot for.

As mentioned above, don't expect it to be a house heater when you're done. If you want to keep the fireplaces unmodified, look into glass doors which can be removed later.

Do you have a plan for adding flue dampers, by the way?

bholler · Jan 15, 2019

jetsam said:
If you finish up and the fireplaces don't work, it's probably because there's not enough flue volume for the opening.

In this case you can reduce the fireplace opening (permanently with brick, or temporarily with fireplace doors) until the opening matches the flue better.

If both liners are 7.5"x7.5", that's 56.25"², so a fireplace opening of 3.9sf would be about what to shoot for.

As mentioned above, don't expect it to be a house heater when you're done. If you want to keep the fireplaces unmodified, look into glass doors which can be removed later.

Do you have a plan for adding flue dampers, by the way?

They have 112.5 sq inches total. So if both liners work as intended there is enough volume.

jetsam · Jan 15, 2019

bholler said:
They have 112.5 sq inches total. So if both liners work as intended there is enough volume.

Oh, both liners are going to the same fireplace? I didn't get that part. So 7.8sf of opening. I guess he does use the singular a lot on the original post. ;em

That makes the question about the flue damper at least twice as tricky!

bholler · Jan 15, 2019

jetsam said:
Oh, both liners are going to the same fireplace? I didn't get that part. So 7.8sf of opening. I guess he does use the singular a lot on the original post.

That makes the question about the flue damper at least twice as tricky!

Also many times on double liner fireplaces only one liner drafts.

HomeinPA · Jan 15, 2019

A couple things (more or less).....

Nobody on here has any thoughts about that firebox and how it is or isn't laid up? Something sure doesn't look quite right to me.

Poured insulation requires a minimum of 1" on all sides of the liner. I don't see that much room on the small side of either flue as they both look to be maybe 9" if he's lucky. Less where the mortar wasn't cleaned off. If his liner is 7.5 ID or OD there is no way it'll be properly insulated and code compliant. Based on the OP's area calculation his liners are ID. He should have a minimum of 10" x 10" ID in the unlined flue.

Why in the world are the liners being pulled up from inside instead of being dropped from the top? You're never going to get it straight enough to insulate it......wait, never mind, I guess that isn't a big deal.

And the biggest question (to me anyway).....Why is Olympia/Copperfield selling this stuff to homeowners? They're supposed to be contractor only.

bholler · Jan 16, 2019

HomeinPA said:
A couple things (more or less).....

Nobody on here has any thoughts about that firebox and how it is or isn't laid up? Something sure doesn't look quite right to me.

Poured insulation requires a minimum of 1" on all sides of the liner. I don't see that much room on the small side of either flue as they both look to be maybe 9" if he's lucky. Less where the mortar wasn't cleaned off. If his liner is 7.5 ID or OD there is no way it'll be properly insulated and code compliant. Based on the OP's area calculation his liners are ID. He should have a minimum of 10" x 10" ID in the unlined flue.

Why in the world are the liners being pulled up from inside instead of being dropped from the top? You're never going to get it straight enough to insulate it......wait, never mind, I guess that isn't a big deal.

And the biggest question (to me anyway).....Why is Olympia/Copperfield selling this stuff to homeowners? They're supposed to be contractor only.

They have been selling to online retailers for a few years now even when they were telling us they werent.

bholler · Jan 16, 2019

And yeah the firebox is really different. Never seen that and not sure how it is structurally sound.

1910Home · Jan 16, 2019

The smaller flue is is a 9" square. The larger flue is 9" x 14".

The liners and all components were purchased through Rockford.

The fireplace was built with the home in 1910. There are two horizontal rows of brick that I removed from the back wall that also were supported by a piece of angle iron. I intend to replace that upon re-assembly.

I have two top-sealing dampers that will go inside a double-flue top cap.

Not sure about the difference feeding down versus pulling up and how straight they would be. The bottoms will have mesh bottom plates attached so that I can finish them in with refractory mortar.

HomeinPA · Jan 16, 2019

1910Home said:
The smaller flue is is a 9" square. The larger flue is 9" x 14".

The liners and all components were purchased through Rockford.

The fireplace was built with the home in 1910. There are two horizontal rows of brick that I removed from the back wall that also were supported by a piece of angle iron. I intend to replace that upon re-assembly.

I have two top-sealing dampers that will go inside a double-flue top cap.

Not sure about the difference feeding down versus pulling up and how straight they would be. The bottoms will have mesh bottom plates attached so that I can finish them in with refractory mortar.

I know what you're trying to do. I understand it completely. As a professional I just would never do it that way. It's all in the installation technique. The liner needs to be straight as possible for insulating purposes. That's not very practically done when trying to bend it around a 90 degree angle in a confined space like the firebox.

And you're missing my main point. You still are not going to have the proper insulation fill to be code compliant or meet the listing requirements. The largest width liner that should be going in either flue, with poured insulation, is 6.5" OD. The rectanglar flue could be 6.5 x 11. I myself would have recommended a nice, clean burning wood stove insert. Runs on one 5.5 or 6 inch liner, uses less wood for more heat, burns much cleaner and makes the west coast enviromentalists much happier.

I know this all looks easy in the YouTube videos and all but it can get a little tricky. Inevitably there are at least one or two details that get left out that will give you a migraine.

1910Home · Jan 16, 2019

HomeinPA said:
I know what you're trying to do. I understand it completely. As a professional I just would never do it that way. It's all in the installation technique. The liner needs to be straight as possible for insulating purposes. That's not very practically done when trying to bend it around a 90 degree angle in a confined space like the firebox.

And you're missing my main point. You still are not going to have the proper insulation fill to be code compliant or meet the listing requirements. The largest width liner that should be going in either flue, with poured insulation, is 6.5" OD. The rectanglar flue could be 6.5 x 11. I myself would have recommended a nice, clean burning wood stove insert. Runs on one 5.5 or 6 inch liner, uses less wood for more heat, burns much cleaner and makes the west coast enviromentalists much happier.

I know this all looks easy in the YouTube videos and all but it can get a little tricky. Inevitably there are at least one or two details that get left out that will give you a migraine.

I get what you are saying. I saw online where many installs were up through the bottom but typically on round liners. Did not think about a square liner having less flex. I guess I will drop them from the top, push them through a bit further to attach the bottom plates and then pull snug into the Smoke Chamber - Flue transition.

I was looking up California codes for chimney flue and with a line it only states a 4" thick brick requirement. Is there another regulation I am missing on this? The flues both still have the original parging, it is just cracked in some areas.

We had many recommend inserts but we are trying to keep our renovation period correct. Plus, heat is really not a big driver for this project. It's more about the ambiance of a fire burning and keeping things close to original. If we get some additional heat out of it that is a bonus at this point, sad to say...

bholler · Jan 16, 2019

1910Home said:
I get what you are saying. I saw online where many installs were up through the bottom but typically on round liners. Did not think about a square liner having less flex. I guess I will drop them from the top, push them through a bit further to attach the bottom plates and then pull snug into the Smoke Chamber - Flue transition.

I was looking up California codes for chimney flue and with a line it only states a 4" thick brick requirement. Is there another regulation I am missing on this? The flues both still have the original parging, it is just cracked in some areas.

We had many recommend inserts but we are trying to keep our renovation period correct. Plus, heat is really not a big driver for this project. It's more about the ambiance of a fire burning and keeping things close to original. If we get some additional heat out of it that is a bonus at this point, sad to say...

4" of brick then an air space 1" for an external chimney 2" for an internal one.

HomeinPA · Jan 16, 2019

1910Home said:
I get what you are saying. I saw online where many installs were up through the bottom but typically on round liners. Did not think about a square liner having less flex. I guess I will drop them from the top, push them through a bit further to attach the bottom plates and then pull snug into the Smoke Chamber - Flue transition.

I was looking up California codes for chimney flue and with a line it only states a 4" thick brick requirement. Is there another regulation I am missing on this? The flues both still have the original parging, it is just cracked in some areas.

We had many recommend inserts but we are trying to keep our renovation period correct. Plus, heat is really not a big driver for this project. It's more about the ambiance of a fire burning and keeping things close to original. If we get some additional heat out of it that is a bonus at this point, sad to say...

bholler said:
4" of brick then an air space 1" for an external chimney 2" for an internal one.

As noted, there is not to be any combustible material, at any point - roof rafters, floor joists, walls etc., within 1" of the exterior of the masonry surface of the chimney where the chimney is completely outside an exterior wall and 2" when it is inside the structure of the home. It is the rare occasion that we find these clearances met so when we install liners we generally assume that if we're putting a liner in, it needs to be insulated to zero clearance as per the manufacturer's instructions. Some manufacturer listings require insulation regardless of the clearances. Best to ask your tech people what the requirements are.

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