Boiler stack penetration
Last Post 13 Oct 2017 10:32 PM by cmkavala. 3 Replies.
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haese56User is Offline
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03 Oct 2017 10:41 PM
Been in a SIPs panel house in Alaska for 5 years and love it. I have a question regarding the roof penetration for out boiler chimney. The sips roof panel was cut away so there's a 2" offset from the metalbestos pipe which I understand for fire safety. There is a metal flashing cap on the roof side, but this has some venting so that it is NOT air tight. On the inside surface there is nothing, just a 2" gap between the sheetrock, OSB, foam, etc, right up to the vented metal cap around the pipe on the roof side. Since the house is so tight, when we run a bathroom exhaust fan the air has to come from somewhere so a good deal of air is drawn through this stack penetration back into the house. Is this acceptable? Or should I be able to get a flashing plate to seal around the stack on the inside? I'm thinking it would have to be specific to the slope of my roof? Or Is there a fireproof foam that could be used? If this does indeed better seal that penetration, where will the intake air come from to feed the bathroom exhaust fan? I have a honeywell HRV system which I run intermitently, will the bathroom fan draw air through that HRV even when it's not running? I know air has to come from somewhere, and there is such a thing as too tight, It just seems like having this fairly substantial "hole" in my roof is not quite the way things should be. The stack goes a good 8' above the roof so I'm really not concerned about boiler exhaust being drawn back in.
Dana1User is Offline
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04 Oct 2017 09:52 PM
The insulated stack pipe manufacturer can probably tell you what materials are and aren't acceptable for sealing the stack boot on the roof. Some aren't very demanding at all, others require only non-combustible materials.

With no better information to work make an air-dam for the bottom side using non-combustible materials (such as sheet steel), and seal the seams & edges with fireproof caulk.

If it's possible get at it to seal the air leaks in the flashing/boot up top with fireproof caulk, do that too.
smartwallUser is Offline
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05 Oct 2017 12:14 PM
Having installed the product, they have interior trim pieces to finish the interior. I'm a little confused why this wasn't done.
cmkavalaUser is Offline
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13 Oct 2017 10:32 PM
Posted By haese56 on 03 Oct 2017 10:41 PM
Been in a SIPs panel house in Alaska for 5 years and love it. I have a question regarding the roof penetration for out boiler chimney. The sips roof panel was cut away so there's a 2" offset from the metalbestos pipe which I understand for fire safety. There is a metal flashing cap on the roof side, but this has some venting so that it is NOT air tight. On the inside surface there is nothing, just a 2" gap between the sheetrock, OSB, foam, etc, right up to the vented metal cap around the pipe on the roof side. Since the house is so tight, when we run a bathroom exhaust fan the air has to come from somewhere so a good deal of air is drawn through this stack penetration back into the house. Is this acceptable? Or should I be able to get a flashing plate to seal around the stack on the inside? I'm thinking it would have to be specific to the slope of my roof? Or Is there a fireproof foam that could be used? If this does indeed better seal that penetration, where will the intake air come from to feed the bathroom exhaust fan? I have a honeywell HRV system which I run intermitently, will the bathroom fan draw air through that HRV even when it's not running? I know air has to come from somewhere, and there is such a thing as too tight, It just seems like having this fairly substantial "hole" in my roof is not quite the way things should be. The stack goes a good 8' above the roof so I'm really not concerned about boiler exhaust being drawn back in.



you can use the HRV as a bath exhaust fan if it is ducted to the bathroom,
I would fabricate d a metal trim piece for the flue if one is not available
Chris Kavala<br>[email protected]<br>1-877-321-SIPS<br />
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