Extending chimney

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JayCee12

New Member
Nov 25, 2021
23
Bushkill, Pa
Hello all, just joined up and I'm looking for some advice. I added a second story onto my house and I need to extend the chimney in order to use the fireplace and eventualy a wod burner. There are two flues one for the basement which is for a wood burning stove not installed yet. And the second bigger one is for the fireplace on the first floor. The block work goes down to the basement which has the two cleanouts and comes up out of the roof. Inside of the block work is terracotta. The fireplace is existing and was used prior to the addition. What would be the best way to transition from the terracotta to class A pipe going up over the second story to meet code? Its needs about 12 more feet on top of existing chimney. Any ideas would be great.
[Hearth.com] Extending chimney
 
JayCee12 said:
Hello all, just joined up and I'm looking for some advice. I added a second story onto my house and I need to extend the chimney in order to use the fireplace and eventualy a wod burner. There are two flues one for the basement which is for a wood burning stove not installed yet. And the second bigger one is for the fireplace on the first floor. The block work goes down to the basement which has the two cleanouts and comes up out of the roof. Inside of the block work is terracotta. The fireplace is existing and was used prior to the addition. What would be the best way to transition from the terracotta to class A pipe going up over the second story to meet code? Its needs about 12 more feet on top of existing chimney. Any ideas would be greatView attachment 286364
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Extending that with class a chimney will be very difficult because the liners are right next to each other. And transitioning from an 8x12 clay to an appropriately sized class a will be very difficult as well
 
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bholler said:
Extending that with class a chimney will be very difficult because the liners are right next to each other. And transitioning from an 8x12 clay to an appropriately sized class a will be very difficult as well
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What about if I seal off the smaller wood burning stove flu and not use it. And just use the one bigger flu.
 
JayCee12 said:
What about if I seal off the smaller wood burning stove flu and not use it. And just use the one bigger flu.
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You still need to figure out how to adapt from 8x12 to a round class a chimney
 
JayCee12 said:
Thats my dilemma, every adapter I see online is not meant to put pipe on top of it, just a hat.
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I have never seen one. I have a feeling it would need to be custom fabricated
 
What about extending it as a masonry chimney?
 
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JayCee12 said:
Really!! Hmmm, Ill have to call in a mason and see what theyll charge to extend. I assumed it would have to be against a wall. Thanks for the info.
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It will need to have rebar in it but it can easily be done
 
EatenByLimestone said:
You could also remove the masonry chimney and go all metal.
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Id have to rip the walls open on the first floor to get to the chase. Its about 5'x5' from the basement to the top of the fireplace then tapers up to 2'x3' through the roof. Its all block with 2 terra-cotta linings, its for 1 wood burner in the basement and the built in fireplace. Worst case, yes I can do that but it would be a mess. Too late in the season to start that. I need to get this going for this heating season, propane is gonna kill me this year $$$$.
 
JayCee12 said:
Id have to rip the walls open on the first floor to get to the chase. Its about 5'x5' from the basement to the top of the fireplace then tapers up to 2'x3' through the roof. Its all block with 2 terra-cotta linings, its for 1 wood burner in the basement and the built in fireplace. Worst case, yes I can do that but it would be a mess. Too late in the season to start that. I need to get this going for this heating season, propane is gonna kill me this year $$$$.
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I doubt you will get it done for the heating season honestly.
 
Before you call the mason let him know if you need or want exposed brick on the interior. He may be able to adapt to blocks which go in a lot quicker.

Years ago I did a couple of block chimneys in borderline freezing weather. We would warm up the space to set a few courses of block then cover the top section where we added the blocks with a trash bag and wrap the outside with foil faced insulation. Then we put a drop light with 100 amp incandescent bulb down in the clean out. Heat rises and the top of the chimney where we were working stayed well over freezing. It also retained the moisture to keep the mortar from drying while it cured. On both of them, once we broke the roof we used regular bricks which was even slower as we were definitely not masons. My buddy has been heating his house exclusively with wood for more than 35 years on that chimney and its still in perfect working order, no cracks and original tile. The only issue is we topped it with salvaged bricks from another chimney and they got beat up a bit chipping off the old fashioned mortar and some had paint on them. The other one I did is used far less but holding up just as well (I paid a mason the do the brick work out through the roof).

I expect most masons would not use the technique as its slow.

I cant comment if its legal but any good sheetmetal shop should be able to make an adaptor out of stainless to adapt from the rectangular flue to the class A. The big concern is not the transition but maintaining clearances with combustibles. Ideally the transition would be to a 6" class A so that the transition pieces could sit down in the chimney tile. The top of the transition would be welded to a horizontal plate that would covet the top of the tile and the brick work with the 6" ring sticking through. The bottom of the transition would sit down inside the existing tile and the seam between the tile and transition would have to be pumped full of refractory cement and then where there is a step it should be smoothed out. Its unlikely the top of the bricks would line up with the top of the tile so once the plate is in place the gap would need to be filled.
 
JayCee12 said:
What 10" pipe? Are you talking about not bottlenecking it, if so there will be a 6" liner from the new insert Im installing.
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Ok you asked about extending it to use the fireplace which is what informed all of my answers. For a 6" liner that's easy. That is the first I have heard anything about an insert
 
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bholler said:
Ok you asked about extending it to use the fireplace which is what informed all of my answers. For a 6" liner that's easy. That is the first I have heard anything about an insert
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Sorry plans just changed tonight, I should have mentioned that. I started another thread with insert questions and forgot to change the plan in this thread.
 
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