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New Hearth Build

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by mepellet, Apr 24, 2013.

  1. begreen

    begreen Mooderator Staff Member

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    I would recommend you put it further from the corners for couple reasons. Maybe 9 or 12" instead. 6" is the minimum for the 1100c. You have a big hearth with plenty of wiggle room and bringing it away from the wall will bring the flue centerline deeper in the room which may be a better match for a larger stove if you upgrade.

    Ray, tiles should be set in latex modified thinset. If using large stone or brick, I think type S mortar is recommended.

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  2. mepellet

    mepellet Minister of Fire

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    2" is the min in a corner installation with double wall stove pipe like I am going to do. Not 6. I am going to do 6 though. 3 times the minimum....
  3. raybonz

    raybonz Minister of Fire

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    Sounds like the thinset I used on my hearth BG..

    Ray
  4. wingsfan

    wingsfan Feeling the Heat

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    The hearth is always cool to the touch, even after the stove has been burning for awhile. I really don't see any problem with it.JMO.
  5. ScotO

    ScotO Guest

    I agree fellas. A lot of people overlook the fact that adhesives are combustible products, in both the wet and dry form.
    For smaller projects, thinset would work in place of mortar for holding stuff together....you could also add a polymer to that thinset.
    But I use mortar for all my builds. Once you learn the different mortars (Portland mix, type-S, type-N, etc.) it's not very hard at all. Actually it's easy and even fun, once you get the hang of it......
    raybonz likes this.
  6. ScotO

    ScotO Guest

    Nobody's pickin on ya. You should be fine, honestly. But I've seen where people used adhesive to 'glue' their tiles to the surrounds of a stove, and those surrounds can get pretty darn hot. In the event of a fire, if the inspectors come to the house and find that adhesive was used in the build, that may nullify your insurance.
    I'm not trying to scare anyone, just putting this out there so people can understand the ramifications that may surface in an event like that.
    wingsfan likes this.
  7. begreen

    begreen Mooderator Staff Member

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    What one does in their own house is their business. The concern here is that many folks visit these threads looking for guidance and ideas for their own installation. Suggesting that adhesive is ok for a hearth is incorrect. When a safety factor is built into the design and specs in the manual or regs, it's for a reason. Chit happens. If the manual requires R=1.5 for the hearth insulation, that is voided by using a combustible product to glue down the tiles. What may seem like a cool hearth today may be much warmer in the middle of a deep cold spell when the stove is cranking 24/7. Look at the rating for the adhesive. Is it approved for hearth use or temps? When in doubt contact the manufacturer.

    Point being that there are lots of shortcuts one can take with stove installations and one might get away with them for years. My wife grew up in a log house built in the early 30s. It had two large stone fireplaces. All was well until one winter in the late 60s when a particularly bad cold snap hit. We had raging fires going in both fireplaces all day long and into the night. Around 3am someone smelled smoke. Turned out the depression era builder had taken a shortcut and supported the upper hearth right on the chestnut log ceiling joists. Fortunately we caught it early and were able to put it out. But the story could have ended up tragically.
    firefighterjake likes this.
  8. wingsfan

    wingsfan Feeling the Heat

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    What would the r value be of 2 inches of solid concrete? anybody know?
  9. 1750

    1750 Feeling the Heat

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    Thermal shielding may be calculated differently (I don't know really anything about this application), but concrete is not a very effective insulator. Typical r-values for concrete vary between about .10 and .20 per inch (concrete is mixed to different densities). So the r-value of 2 inches of a normal weight concrete would be considerably less than 1.0.
  10. Big Donnie Brasco

    Big Donnie Brasco Feeling the Heat

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    Unfortunately Drolet now requires 1.0 :(
  11. raybonz

    raybonz Minister of Fire

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    Bummer Don but you do have options just something to consider..

    Ray
  12. mepellet

    mepellet Minister of Fire

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    Finally started demo of the old hearth because we finally decided on tile. Going to go with two layers of cement board (1/2" ea) and then 12Support porcelain tile with a diamond border in the front.

    How do you like the wallpaper? Think the thimble was installed correctly? Going to take all the brick off the wall and under the stove and then patch the drywall, paint the room, do the tile, and then the new chimney. Selkirk supervent straight up with an offset in the attic above.

    Attached Files:

  13. begreen

    begreen Mooderator Staff Member

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    Hmmm, the thimble looks suspect. How close is the nearest combustible. Looks like less than the required 12" of brick in both directions there and definitely less to the wall paper. It's a good thing you are investigating.
  14. begreen

    begreen Mooderator Staff Member

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    All Drolets?
  15. Big Donnie Brasco

    Big Donnie Brasco Feeling the Heat

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    According to the online manuals that I read.
  16. begreen

    begreen Mooderator Staff Member

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    Random check seems to show that the ADIRONDACK, JURASSIEN, CELTIC AND SAVANNAH models are still ember protection only. Not sure about the rest of the line.
    raybonz and Big Donnie Brasco like this.
  17. mepellet

    mepellet Minister of Fire

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    Do you really think there is a thimble there? It doesn't look so to me but maybe I am wrong. Looks like just the inside edge of the cleanout tee. See pictures.

    The nearest combustible will likely be the wood sheathing which is probably touching the cleanout tee. I will uncover that sometime soon. The drywall/wallpaper is 4" from the top of the stove pipe, 10" from the right side of the stove pipe and 8" from the left side of the stove pipe.

    Attached Files:

  18. begreen

    begreen Mooderator Staff Member

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    :eek: You are on site and have the full view. The first picture posted shows class A in the wall which I was taking for a thimble, not the end of the tee. The outside shot makes me a bit queezy. ;hm
  19. mepellet

    mepellet Minister of Fire

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    Yea. It looks like they didn't use a thimble. Just stuck the tee in through the wall and sided around it and then put brick around it in the wall and on the inside face of the wall.
  20. mepellet

    mepellet Minister of Fire

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    Ok, got most of the brick off the wall. Directly behind the brick was about a 1/2" of air space (not ventilated at the bottom) and then 1/4" shet of plywood. I assume the plywood is on top of the drywall. Haven't taken it down yet. Glad I am not re-using the existing hearth!

    Anyway, like I said, I got most of the brick off the wall. Just have the bottom couple rows to remove where the chisel wouldn't fit to tap the bricks up. So I started working on the floor. What I was hoping to be two layers of brick, is actually a poured concrete solid mass that is wrapped on the sides and top with bricks. The bricks were not messy. Just a couple taps and they came loose. Any ideas on how to remove the concrete without too much of a mess?
  21. mepellet

    mepellet Minister of Fire

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    Just started taking the brick out from inside the wall around the cleanout tee. As expected, they just stuck the tee right through the wall with no thimble.

    Attached Files:

  22. begreen

    begreen Mooderator Staff Member

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    Now I'm definitely queezy. :confused: Good to see you are correcting this.
    PapaDave likes this.
  23. mepellet

    mepellet Minister of Fire

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    Queezy from the lack of thimble or the awesome wallpaper? ;-)
    begreen likes this.
  24. mepellet

    mepellet Minister of Fire

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    A few weeks ago I went to the local Lowes and bought the ceramic tile, grout, mortar and hardibacker. After doing a search here on hearth.com for how to best cut the hardibacker, I came across posts saying that hardibacker is not supposed to be used in hearth installations. I then came across posts that said that the durock next generation is also not supposed to be used for hearth installations. Lowes website doesn’t specify if the durock cement board they sell is next generation or not. I don’t know what to trust anymore. Is either one acceptable for use in my hearth under my stove?

    According to the hardibacker website the “approximate” R value is 0.13 per ¼”
    Manuf. Link: http://www.jameshardie.com/homeowner/products_backerboard_halfInch.shtml
    Lowes link: http://www.lowes.com/pd_11640-12755-220001_0__?Ntt=hardibacker&UserSearch=hardibacker&productId=1005411&rpp=32

    According to the durock website the R value is 0.39 for ½” thickness
    Manuf. Link: http://www.usg.com/rc/data-submittal-sheets/panels/durock/durock-cement-board-submittal-CB399.pdf
    Lowes link: http://www.lowes.com/pd_65361-325-172964_0__?productId=3265973&Ntt=durock&pl=1&currentURL=%3FNtt%3Ddurock&facetInfo=

    Could someone please confirm that I am reading the R values correctly?

    If they are both acceptable for hearth installations and the R values that I note above are correct, I might return the hardibacker and buy the durock, not to save money (durock is slightly cheaper) but to achieve a higher R value. Even though my current stove doesn’t require it, I would like the most “reasonably” possible so that if we change the stove out, I will not have replace the hearth.
  25. Jags

    Jags Moderate Moderator Staff Member

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    The original Durock was "hearth" approved. The next gen did not carry that approval. The next gen had styrofoam perlite beads added to the mix to make it lighter. But it also cost it the hearth approval.

    Check Wonderboard. I think it is listed for hearth but double check that.

    Hmmm...wonderboard is now called wonderboard lite. I wonder if it met the same fate as the Durock.

    UPDATE: Made a call to USG (Durock). The board is fire rated, but DOES NOT have the hearth approval. This is the third call I have made in as many years and the answer has been consistent. Proceed as you see fit.

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