Simple question and probably stupid question...but this forum is generous

JPapiPE Posted By JPapiPE, Jul 11, 2008 at 4:04 PM

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  1. JPapiPE

    JPapiPE
    New Member

    Jun 10, 2008
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    Loc:
    South-West hills of Maine, Red Neck Country
    What is the clearance for HT A-type chimney as it goes thru the roof and attic? I have an insulated attic and think the clearance is 2" I also have a 1/2" decking (roof sheathing) beneath my metal roof. and suspect the clearances should be 2" around the wood roof sheathing, but could come in contact with my metal roof. Is any of this correct?
     
  2. Highbeam

    Highbeam
    Minister of Fire

    Dec 28, 2006
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    Loc:
    Cascade Foothills, WA
    My installer cut the roof hole (sheeting and comp roof) large enough to provide the 2" required clearance. The 2" is clearance to combustibles so you could make a case that the metal part of your roof is non-combustible but the sheathing has to be cut anyway.
     
  3. JPapiPE

    JPapiPE
    New Member

    Jun 10, 2008
    408
    0
    Loc:
    South-West hills of Maine, Red Neck Country
    When you say 2" clearance you mean 2" all the around the chimney right? So the total hole would be 4" larger than the pipe diameter. Example a 6" pipe would require a 10" hole from my combustible roof sheathing and also a 10" clearance where my chimney passes through my insulation? Giving it 2" on all sides. Is this correct?
    Thanks so much , I do think i understand this principle
     
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