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smoke pipe clearence

JBee_8 Member Posts: 4
Dry wall is not a combustible it is rated for 1hr if 5/8" thick. You can put a piece of sheet metal between the smoke pipe and the combustible to cut down on the required clearances. Doubled walled smoke pipe for wood stoves does this but, it cost more. The wood behind the sheetrock is a combustable and the heat will go thru the rock to it.


    STEVEN MARKS Member Posts: 154
    smoke pipe clearence

    Can someone tell me what the required clearence would be for smoke pipe from an oil fired boiler to fire rated sheetrock. 18"?

    Costumer finished basement and is only 3" from smoke pipe.

    Thanks for any help
  • Bob Harper
    Bob Harper Member Posts: 1,026
    Check listing

    Some appliances state a clearance as close as 9" but if not listed, then the default is always 18". What kind of chimney is this going into that has a drywall up to it? Masonry chimneys must have a 1 or 2" clearance to combustibles, which would preclude drywall in contact.
  • Bob Harper
    Bob Harper Member Posts: 1,026
    got your facts wrong JB

    Sorry but according to the NFPA, the definitions for combustible and noncombustible recognize inorganic materials or those having passed ASTM E-136. Typical 5/8" fire rated drywall has a flame spread rating of 15 under ASTM E- 84, which means it burns 15% as fas as red oak in a Steiner Tunnel test---but it still burns! In an ASTM E- 136 750c vertical tube furnace, drywall is utterly destroyed so it is "combustible". Check your sources.

    One layer of 5/8" type X drywall yields a 30 minute fire rating when applied over 2x4 studs. If you insulate that stud wall with R-11 fiberglass batts with type X on both sides, you get a 1 hr. rated wall per the IBC.

    You can make ventilated heat shields per NFPA 211 and reduce a vertical clearance a maximum of 50%. You can use type 'L' vent for oil for a 9" clearance or B-vent with gas for a 1" clearance.

  • JBee_8
    JBee_8 Member Posts: 4

    Could you please tell me how many men make up a fire company according to the NFPA? Because when their numbers don't work out that is who comes to fix it. I have called them but they are silent. The NFPA has a lot of numbers but none for a fire company manning? Why is that? When their numbers don't work out who do you call? Why is the NFPA the be all and end all when it comes to numbers? By the way everything burns even steel that is how it is made. In a volcano stone burns so what. Time distance and tempature are the determining things.
  • Bob H is correct


    Whether anyone likes it or not, NFPA is an accepted "Standard of Care" throughout the HVAC industry, and more important by the courts who sort out the problems when things go wrong.

    (My 2006 version is at the office)

    NFPA 211/2003 211-8, 3.3.26 Combustible material. Material made or surfaces with wood, compressed paper, plant fibers, plastics, or other material that can ignite and burn, whether flame proofed or not, or whether plastered or unplastered.

    Sure sounds like they are describing sheet rock to me.

    Bottom line is, if you do follow the approved clearances or the approved clearance reduction methods exactly, as they are written in NFPA 211, you will not have a problem. They simply work.

    And by the way, after the FD leaves, the fire investigator must conduct his fire investigation within the accepted “Standard of Care” as is set forth in NFPA 921, the Guide for Fire & Explosion investigations.

    Bob H is right on point.

    Ed Carey
  • J.C.A._3
    J.C.A._3 Member Posts: 2,981
    In MOST cases....

    The "venting" portion" of all I and O manuals describe and recommend "MINIMAL clearances for all of the venting options". When in doubt...refer to the instructions.(For some reason...it ALWAYS seems to be the lengthiest portion of most I and O books)

    If for some strange reason the clearances AREN'T there, NFPA is what any inspector worth his salt will refer to.

    The manufacturers for the most part, have written their clearances in their manuals because of their extensive testing...and the I and O book IS what inspectors HAVE to accept. (Unless they are on a power trip and want to exceed it....they will more likely than not, lose in a battle in a court of law.) Chris
    STEVEN MARKS Member Posts: 154

    Thanks for the reply's.
    I was looking for comfirmation before I told the owners they had to move the wall before I installed a new boiler. They didn't know they had to pull a permit when they remodeled the basement.
    I also told them to be prepaired for the inspector to vent when he comes to inspect the new boiler.

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