Air sealing wood stove chimney
Hi all,
I’m installing a class A (insulated double wall) chimney pipe through a cathedral ceiling, and I can’t find a good way to maintain continuity between the pipe and the ceiling air-barrier (Intello membrane).
My local installer is not familiar with air-sealing details, his installation would use a radiation shield (example attached) as the pipe passes through the ceiling plane. But this leaves a 1” air gap between the pipe and the shield, with no flange connecting them at the bottom.
Does anyone have experience with this air-sealing detail? I’m aware that this is precisely the reason wood-stoves are not ideal in a high-performance build, but perhaps someone has found a way to make it work?
I had originally figured on using a standard support box, which has a flange that connects to the pipe (closing any air-gap and providing a flat surface to attach a membrane to), but this flange only connects to interior pipe. This is a 2-story house so the interior pipe transitions to Class-A at the 1st floor ceiling, then class-A all the way up to the cathedral ceiling.
Thanks,
Adam
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Replies
Adam,
Many manufactures have cathedral supports with built in transitions so you can go from single or double walled pipe to insulated, others supply a separate transition piece. Either way it’s a very standard detail. The box is easy to air-seal both to the ceiling with a flange, and the single pipe below.
Here is a photo of the last one I did:
Thanks Malcolm. Yes I’m familiar with the support boxes, but as far as I know they are only for transitioning from double walled to insulated pipe. My house is 2 stories, and since the pipe must transition to insulated pipe at the first floor ceiling (by code), it won’t fit any standard support box when it gets to the cathedral ceiling on the second floor. It must use a “pass-through”, as my installer called it (radiation shield).
I did find a round trim piece for pitched ceilings from ICC, I may be able to use this and seal any other gaps with high temp caulk.
Adam
Adam,
Sorry I understand now. That's the condition I have in my own house - insulated pipe from the first floor ceiling right up through the second floor and out the roof.
I used the round trim. It was easy to seal to the pipe and drywall with high heat caulk.