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88bomber 02-02-2013 12:13 AM

finish basement with metal-fab chimney
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I want to finish my basement. I was planning on using 2" xps foam board, 1" furring strips, and 1/2" drywall. I have a question on how to work around the metal-fab chimney pipe that comes through the concrete block wall. (see pics)

I think the installer had a "wall firestop assembly" (TGWFSP), but didn't want to cut the hole big enough to use it, so I think he cut the cylinders off the TGWFSP, used the back plate on the outside of the concrete wall, and left the front plate for me to use however I wish. I do see fireblock caulking was used on the outside to seal the hole through the concrete.

Should I buy another TGWFSP, put it over the class A pipe and run my foam right up to the protective cylinder of the TGWFSP?

Do I even need to buy one as long as I keep the clearance? Maybe just build a wood frame (17"x17") around the class A pipe with 2.5" clearance, and install the leftover plate flush, running the drywall up to the edge of it. I could leave the foam outside the wood frame and dead air space between the frame and the class A pipe?

Also, what should I use to seal around the class A pipe and the concrete block (if anything)?


beenthere 02-02-2013 07:05 AM

Looks like your finished wall thickness will put it out over the single wall pipe, which will require a 6" clearance around it.

88bomber 02-02-2013 08:03 AM

I have 3.25" from the wall to the end of the class A pipe on top, and 3.75" at the bottom (its angled up slightly obviously).

beenthere 02-02-2013 08:21 AM

Single wall requires 6" in all directions.

88bomber 02-02-2013 08:31 AM

So what if I used double wall stove pipe instead?
With the black trim plate I have, that would give me 4.5" to sheet rock.

Or, I guess I could use backer board + ceramic tile or "thin brick" instead of sheet rock for a small area behind the wood heater...that would work too right?

With either option, I still need to know what I should do behind the wall with regard to the XPS foam board and class A pipe.

So basically, the installer should have run the class A pipe 6" further into the room I guess.


beenthere 02-02-2013 11:31 AM

A small piece of the B vent to extend it further into the room will work fine. Not uncommon to do it the way it was done in an unfinished basement. But if he knew you were thinking of finishing it. He should have installed the complete fire stop/thimble assembly.

I would get a piece of 6" single wall pipe or what ever size the opening in your fire stop cover is. Fasten it to the cover and then slide it in the opening you leave in your finished wall and fasten the fire stop plate to the wall. That should get you your clearance. Also caulk the B vent to the block wall.

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