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Question on running 6" double wall chimney pipe through roof overhang.

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by buckwheat12n, Aug 1, 2006.

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  1. buckwheat12n

    buckwheat12n New Member

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    What would be the minimum amount of roof overhang I would need to safely run 6" double wall pipe through? I have either 15"-18" (I know it's one of the two measurements just haven't taken a tape measure up to double check) where I want to run my chimney pipe through, I had someone tell me that 15"-18" wouldn't be enough and I'd have to run the pipe around the overhang. Does anyone know for sure what the minimum would be? Thanks!

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  2. elkimmeg

    elkimmeg Guest

    The pipe has to extend beyond any part of the roof 3' and be 2' higher than any part of the roof or structure with in 10'
    Say you had a 6" pitch per ft a common pitch 10x 6=60" plus the 2' over +24" you would have to be 84" above the overhang of that roof. Then one also has to factor in the min verticle run listed with your stove. Once you approach or exceed 3/4 ft in height, a chimney brace would be required. I mot pulling any of this out of thin air, these are actuall governing codes, NFPA 211 or The International Mechanical Codes and I am sure also as instructed with by your flue pipe manufacturer and within the listing of the stove manufacture specs. Every elbow requires additional height in the Verticle rise. For instance every 45 degree elbow 2.5' is added to the 7' already required a 90 drgree elbow adds 5'. Total change in directions are limited to 180 degrees in bends. IN other words from the stove collar an equilvant of only 2 90 degree elbows may be used A tee box in not included in the degree bend formula
  3. buckwheat12n

    buckwheat12n New Member

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    Thanks for the info! I was actually wanting to know if there was a specification for running 6" double wall chimney through a roof overhang (part of roof extending over exterior wall of house). I have a 15"-18" overhang, can 6" double-wall chimney pipe be ran through that or is that not enough overhang?
  4. Roospike

    Roospike New Member

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    The standard stainless steel 6" pipe is 8 3/4" wide and needs 2" clearance on all sides so you would have a 12 3/4" ( 13") hole in the roof . Also you would need to have 2" clearance from the wall so with the 13" hole that kicks the far end of the hole edge out at least 15" from your wall. Just to give you a guide line .
  5. Metal

    Metal Minister of Fire

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    Metal-Fab Temp Guard is listed to 1.5" clearance to combustibles, so that would save you 1" on the hole size and let you place the pipe 1/2" closer to the house, which in your case may make the difference in fitting or not. That would make the outside of the hole 12 7/16" from the wall (from Installation Instructions). The CTC is part of the hole.
  6. hearthtools

    hearthtools Moderator Emeritus

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    are you asking about Double wall pipe or Class A chimney?
    Double wall pipe (to us) is the pipe that connect to a stove and then connects to a Class A chimney.
  7. MountainStoveGuy

    MountainStoveGuy New Member

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    Metal, this document states that it needs 2" of clearance, and isnt metal fab a 9" OD? Temp Guard
  8. MountainStoveGuy

    MountainStoveGuy New Member

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    Roo, normally you would notch out the facia and finish it out. Most chimney pipe is designed to fit between standard 16" centers or less (14.5") . 6" chimney is typically 8" OD with a 2" clearance you will get 14" space required for proper clearance.
  9. Roospike

    Roospike New Member

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    I measured mine ( metal fab class A SSteel ) and it showed 8 3/4" It might be stated as 9"
  10. Roospike

    Roospike New Member

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    What about running it on the inside of your home ? That would be better yet if you can find the room . Less problem with a 1 story house. 2 story would need the room up stairs . What style of house do you have ? 1 story , 2 story . 3 ? can you run it through the inside?
  11. Roospike

    Roospike New Member

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    We remodeled a 100 + year old home .......What is 16" centers ? what is square ? Ha ! With an older home you have to close one eye and stick you thumb in the air in front of you just like they seem to do 100+ years ago . "Yep , that looks about right"
  12. skypager

    skypager New Member

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    In many cases even if there is enough room to run the class a chimney through the roof the base of the cone on the flashing is to wide.

    For example: (using DuraTech specs)

    A 6" ID class a pipe is 8" OD and needs 2" clearance. So a 12" hole is needed.

    But....

    The bottom of the cone on the roof flashing (assuming pitch is 6/12 or under) has a diameter of 17" and the flat base of the flashing is 27". This means that from the center of where the pipe exits the roof to the edge of the overhang you will need around 14". (give or take a little because the cone is not centered on the flat part) Probably not enough there and you probably won't be able to get a good seal on the flashing.

    My suggestion... Unless its at least 2' or greater - go around it. The savings on the price of a few 30 deg elbows or the astetic value is probably not worth the frustration and possible problems that will arise in attempting this.

    Hope this makes sense.
  13. RoosterBoy

    RoosterBoy New Member

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    hi josh your saying a 6 inch class (A) has a 8 inch od witch is true most do. and that Class (A) requires 2 inch clearance so that would make a 10 inch square hole around the pipe not 12 like your saying right?

    thanks
    Jason
  14. MountainStoveGuy

    MountainStoveGuy New Member

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    you have a total of 2" on both sides, wich will give a 8" OD pipe a 12 inch hole, and a 9" a 13" hole.
  15. hearthtools

    hearthtools Moderator Emeritus

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    Then you have to go larger on the up and down for the pitch of the roof.
    So it depend if you are talking about the Eve side of the home or the Bardge side (end of the Pitched roof)

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  16. skypager

    skypager New Member

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    Very true. Didn't occur to me at that moment.
  17. hearthtools

    hearthtools Moderator Emeritus

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    ICC through wall and up.

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  18. buckwheat12n

    buckwheat12n New Member

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    Thanks for all the info guys! I did go out and measure...the overhang is 15" and is on pitched side of the roof. I knew the pipe would have an 8" O.D. but I see now where the flashing could cause a problem. I have a ranch...I'm not to keen on running the pipe through one of my bedrooms to get out through the roof. I guess running around the overhang would be the next best option, how is the pipe for something like that normally ran? Thanks again.
  19. skypager

    skypager New Member

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    I couldn't find a picture of a run with an offset. Rod, do you have one? Or maybe someone could supply a pic of their run?

    The run would look like the picture above (the one on the left) but would have a 15 or 30 deg offset and return to go around the overhang. The flashing is then eliminated and a few more braces are needed to secure it.

    Every brand of Class A chimney is a little different in specs, clearances, and the actual installation components. Do you know which brand you will be using?

    Side note: In the US 45 deg offsets cannot be used and the only 90 deg turn acceptable is the tee w/ cleanout turning upward.
  20. hearthtools

    hearthtools Moderator Emeritus

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    30 deg elbo option would cost and average of $275 more Just for the 2 30 Elbos
    if not enough clearance to the Facia then best to cut out like the first photo I posted

    But if he has 18" I think he has enough room.
  21. Corie

    Corie Minister of Fire

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  22. Metal

    Metal Minister of Fire

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    MSG- ALWAYS follow the Manufacturer's Installation Instructions, not a spec sheet. The Installation Instructions for Metal-Fab TempGuard Pipe states 1 1/2" CTC for 6" and 8" diameters.
  23. MountainStoveGuy

    MountainStoveGuy New Member

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    Metal, what i have in my hands is this
    "metal fab installation and maintenance instructions for 2100* temp guard chimney"

    On the front of it it states this:
    "A major cause of chimney related fires is failure to maintain required clearances to combustible material. *minumium clearance for temp guard is 2 inches. It is of utmost importance that this chimney be installed only in accordance with these instructions"

    Do you have documentaion that states otherwise?
  24. buckwheat12n

    buckwheat12n New Member

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    Ok, thanks for the pics. I'm going to possibly try to pickup up what I need tomorrow from a local dealer. I will check with them as well and see what they think. I think, worse case scenerio, I could notch out the overhang as pictured above or just go around it if the flashing ends up being to big at the base. All the info definately helped to give me some ideas.
  25. Roospike

    Roospike New Member

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    I had noticed in the picture that the looks of the Boxed in chimney vs the open non-boxed chimney that the boxed in shows a vented flashing cap for the pipe and the open does not . This has come up per vented vs non vented flashing . Per the picture ........... is this the rule ?

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