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Some help installing a new wood stove chimney

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by bayshorecs, Sep 28, 2008.

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  1. bayshorecs

    bayshorecs New Member

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    Hi all, new to the forum and looking for some advice on adding a chimney.

    I dabble in contruction some and have family who have built their homes after the framing was done, so I am not too worried about the contruction of the chimney, but I want to be sure I am to code.

    I recently purchased a Century Hearth FW300011 from Menards and I plan to install it in the finished basement. The stove pipe/chimney will come up out of the stove, 90 into the finished wall, 90 straight up along the side of the house, through the eave and out the roof. Most of it seems straight forward once I know what needs to be done.

    For the questions/notes:

    1. The hearth will be a 5x5 slate tile on concrete.
    2. The finished wall is a piece of drywall on a stud with cinder block behind it. Do I need a thimble for going through this wall? The studs are 24" apart, do i need to center the chimney in this space or to I need to attach to one of the studs?
    3. I have a 2' eave which the chimney will need to go through. what is used for making it through the eave?
    4. I have a 5/12 pitch on the roof line. I think I need just over 4' of chimney after clearing the roof for code. Manual states 15' min height on the chimney which I will clear no problem.
    5. What kind of pipe for each section and is there a good place to get it online? Or should I just go back to menards to get that stuff?
    6. Stove will be 15-18" from the back wall and have over 25" of hearth in front of the stove.
    7. I noticed some thimbles are about 12"x12". I was expecting just to take out 1 block which is 8x12. do I have any other options?
    8. How do I remove the block and do I need to fill the cavity between the drywall and block next to the pipe?
    9. Was not planning on adding a chase right now. Maybe in the spring.

    sorry for the long post. I was planning on asking a few local contractors but none are returning phone calls for come reason.

    I also added some pictures of the install location.
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]


    Thanks! Any help would be great! I would love to get the floor down this week but the chimney placement can make it shift a few inches either way and I would like it to be centered.

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  2. KeithO

    KeithO Minister of Fire

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    It will all be class A pipe going through the drywall/insulation then the cinder block. Class A has a 2" clearance to combustibles MINIMUM. Menards will have a wall thimble that is not very big. If a stud is in the wrong location, frame in a "box" you need for attachment of the thimble anyway. If you are perfectly between 2 studs, all you need is an upper and lower header. Just be sure than NO INSULATION violates the 2" clearance requirement. At least going through the cinder block wall should be OK unless you hit reinforcing. I have to go through a poured wall soon, yuk yuk..... Just to be clear, I would leave 1/4-1/2" on the hole through the cinder block (it is not combustible) and the metal thimble goes on the inside wall which you have finished with framing and sheet rock.

    More than likely you will need to extend quite a height above the eaves to meet the 2/10 rule. That almost certainly dictates a set of stays to support the chimney (max 5ft between support points). Same clearance requirement applies outside (2" radially)

    Single wall stovepipe requires 18" clearance from the sheet rock. If you add an appropriate metal heat shield to the single wall it will probably be fine. Else double wall. Menards has double wall, only problem is that our store stocks only 24"lengths and no telescopic lengths at all. Don't make the mistake of skipping on a telescopic length, it makes the initial install easier and future cleaning a peice of cake.
  3. begreen

    begreen Mooderator Staff Member

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    Hopefully some folks that have done this recently can chime in soon. You will need a thimble, but the 12 x 12 part is not the dimension of the hole in the wall. That hole needs to be large enough to pass a section of class A pipe which is about 8" in diameter. The 12 x 12 collar is to keep it 2" away from the nearest wood. If you can, you might be able to catch a stud on one end, but most likely you'll be attaching the interior frame of the thimble between a pair of horizontal 2x4s framed in to attach to the wall studs. It seems like you might get away with pulling out 3/4s of a single block, but I'd rather you got guidance from someone that has gone through the process successfully.

    In the meantime, here's an article to get you started:

    http://hearth.com/econtent/index.php/articles/passing_a_chimney
  4. bayshorecs

    bayshorecs New Member

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    I guess I missed the 2' clearance ABOVE anything within 10'. That makes it at least 6' above the shingles with the 5/12 pitch to clear that.

    Sounds like the thimble might be a pain. I was hoping to only cut the hole size which would be covered by the collar and not need to replaster the wall. But, if I have to frame in a support, that may not be possible. :(

    what about the eave rafter? I guess I need to figure out where that is so that it does not mess up where the chinmey and studs are. that would suck to find out about afterwards!

    what needs to be done for going through the eave?

    So black stove pipe to the thimble on the inside then class A the rest of the way? Sound like double wall may be more expensive, but certainly the better way to go.
  5. begreen

    begreen Mooderator Staff Member

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    Cutting a section of sheetrock out to put in the headers is not a big deal. If you screw the headers into the studs instead of nailing, it will not pop any sheetrock nails. More important is to try to align the thimble to be centered between the roof's rafter tails. You'll need to remove the soffit vents and cut an oval hole for the pipe to pass through, with at least 2" clearance on all sides. A sawzall with a short blade works well for this. Or you could box frame the soffit for the chase and run the pipe up through the clear opening.

    I'd recommend downloading a couple of the installation guides published by the stove pipe makers. Simpson has a good one for starters.

    On Simpson's site, go to http://www.duravent.com/?page=ts.php and in the second popup (installation pdfs) choose DuraTech 5" to 8".
  6. bayshorecs

    bayshorecs New Member

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    Thanks for the links. I also found a link searching for pipe for dynamitebuys for dura-vent and those prices look better than anywhere else I have seen so far.

    I was planning on using galzanized pipe without a chase (at least until spring), but from posts here, that sounds like it may be a bad idea. I would hate to destroy the piping in a season with it being exposed. Do you think it would hold up ok without the stainless?

    Going to work up a parts list and post it to see if I am missing anything. I am sure the pipe lengths might change some.
  7. bayshorecs

    bayshorecs New Member

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    How does this hardware list look? It comes to about $800. Also, would I only be using 1/2 of the thimble as the back side of it is block?

    Simpson Dura-Vent 6'' DuraBlack Stovetop Adapter - 1677
    Simpson Dura-Vent 6'' DuraBlack 24'' Single-Wall Black Pipe - 1624
    Simpson Dura-Vent 6'' DuraBlack 90° Elbow - 1690
    Simpson Dura-Vent 6'' DuraBlack 12'' Single-Wall Black Pipe - 1612
    Simpson Dura-Vent 6'' DuraTech Wall Thimble - 9443
    Simpson Dura-Vent 6'' DuraTech Tee With Cap - 9467
    Simpson Dura-Vent 6'' x 9'' DuraTech Chimney Pipe - 9408
    (2) Simpson Dura-Vent 6'' x 60'' DuraTech Chimney Pipe - 9409CF
    Simpson Dura-Vent 6'' x 24'' DuraTech Chimney Pipe - 9405
    Simpson Dura-Vent 6'' DuraTech Roof Flashings 0-6 Adjustable - 9449LB
    Simpson Dura-Vent 6'' DuraTech Chimney Cap - 9484
    Simpson Dura-Vent 6'' DuraTech Adjustable Tee Support Bracket - 9472
    Simpson Dura-Vent 6'' DuraTech Storm Collar - 9459
    (3) Simpson Dura-Vent 6'' DuraTech Adjustable Wall Strap - 9468
  8. begreen

    begreen Mooderator Staff Member

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    The smoke has to go through 2 -90 deg. turns which will decrease draft. I'd use double-wall DVL pipe on the interior. It will reduce clearances and draft better. Note that you should not have the DVL pipe closer than 9" to the ceiling or floor joists, 18" if single wall. The class A pipe should project into the room 6", I would plan on a 12" stub to go through the wall. 12' of vertical pipe seems shy of requirements for the vertical run to make the 10/3/2 requirements. That will require a roof brace for every 5 ft of pipe above the roof.
  9. bayshorecs

    bayshorecs New Member

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    Looking at my numbers again, I think I need a couple more feet out the top. From my notes:

    4' after roof line
    2' off the ground
    1' through the eave
    10' to the eave

    So, (10-2)+1+4=13' min of vertical pipe outside the house and I listed only 12'...guess I will change the top piece from a 2; to a 4' and add a brace.

    So double wall on the inside to help with the drafting. What about the 90? They don't make a double wall 90 I though, only in single wall stove pipe.

    Also trying to understand how the top of the stove which is 6" goes down to a 3" or so inside pipe on the DVL. Is the bottom of the DVL sealed or something? No problems with air restriction?
  10. bayshorecs

    bayshorecs New Member

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    Wait, I see. I have DVL and duratech mixed up. DVL is double wall for inside and duratech is double wall for outside?
  11. Brian VT

    Brian VT Minister of Fire

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    I think he'll want an 18" to go through cinder block+framed interior ?
  12. bayshorecs

    bayshorecs New Member

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    I was thinking about using a 24" piece. I need 18" from the wall to stove + distance through block+frame to the T. So the duratech goes from the T through the thimble directly into the DVL 90. Then 2' down to the stove with a DVL to stove adapter.
  13. begreen

    begreen Mooderator Staff Member

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    Correct. It is confusing, they are both double-wall. DVL is for the interior connector. DuraTech is the class A pipe.
  14. begreen

    begreen Mooderator Staff Member

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    Right Brian, good catch.
  15. bayshorecs

    bayshorecs New Member

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    Updated list is around 1k for piping/fittings/connectors....ugh...

    If I go through the eave (instead of notching it), what do people use on the underside of the soffit for protection? A firestop radiation shield?
  16. Brian VT

    Brian VT Minister of Fire

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    As long as you're 2" away (pipe centered in 10"+ wide oval hole) you don't need to protect it.
  17. bayshorecs

    bayshorecs New Member

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    What about the connection from class A to DVL? Is there an adaptor of some sort? I haven't seen one listed yet.
  18. bayshorecs

    bayshorecs New Member

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    Oh, now I see it in the DVL section.

    Simpson Dura-Vent 6'' DVL/DuraBlack Chimney Adapter - 8674
  19. bayshorecs

    bayshorecs New Member

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    Ok, I think I have the final layout. Someone please look this over before I buy all this stuff!

    I changed the 5' Duratech sections to 5 3' sections fearing shipping may destroy the 5' long stuff. I also added the fire shield on the soffit and the dvl to duratech adaptor.

    Does this look right?!?

    [​IMG]
  20. begreen

    begreen Mooderator Staff Member

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    Great that you are diagramming this out. That really helps. The only thing that seems awry is the stack height. If this is a 5.5 pitch roof, then in 10 ft rise it should be 55" higher. To be 2 ft higher I think the stack needs to be at least 79" above the roof. Can someone else confirm?

    Also, if you are planning on enclosing in a chase next year, maybe start the planning now. You can center the flue between the rafter tails or at least allow for 2" or greater clearances. But why not box out the soffit now in preparation for the chase? Then no storm collar or roof flashing will be required. Just a thought.
  21. bayshorecs

    bayshorecs New Member

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    I did some quick math in the beginning. Maybe I messed up.

    with a 5x12 pitch, 10' or 120" inches from the stack comes out to 50.25" vertical. add another 24" to that and I get 74.25" high.

    the thimble is at 2' off the ground. I should pick up around 6" from the tee I would think. which puts me at about 80". Granted, I did not account for sleeving the pipes...maybe I should add another 1' or 2' section then just to be sure.

    For the chase, you say box out the soffit and install the shield (or not if I have enough clearance, might anyway to help center things). What about the top side of the roof? Just notch out the soffit area completely and center the flue in the hole?

    This site is great! Reminds me of the TDIClub site. Always help just a post away. Especially after talking to a dealer today...$1500-$2000 in parts and $1500 install was their estimate. And, they tried to tell me that my insurance may not cover the stove from Menards if I install it...sounds like a car dealer to me...
  22. Hogwildz

    Hogwildz Minister of Fire

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    I prolly am missing something, but why not go straight up from the stove?
  23. begreen

    begreen Mooderator Staff Member

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    My mistake, (head slap) you did say 5/12, not 5.5/12. 74" it is. Yes, to the soffit question. If it is going to be chased next year, then no need to deal with the roof flashing cost and storm collar. Box in the area and keep the pipe going straight up and brace it. Hog is the roofer and may find some caveats with my plan. But it makes sense to me to set up things for the future.
  24. Hogwildz

    Hogwildz Minister of Fire

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    I'd flash the roof temporarily at least. You don't really want water running down the soffit, then down the pipe. ANd if the soffit is pitched back to the house, any water that gets in there could cause water damage if it builds up in there.
  25. bayshorecs

    bayshorecs New Member

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    Great. Thanks guys!

    I can't go straight up. This is in the bottom level of a tri-level house so the second story is above the room with the stove. I didn't draw the floors on the pic.

    Looks like I just need to shore up my lengths a little and start ordering parts!

    You guys agree that ordering 3' pipe is better than 4' or 5' due to possible shipping damage?
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