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Cement board research....

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Gooserider, Sep 11, 2007.

  1. mhrischuk

    mhrischuk Guest

    Looks good. Another option would have been just squares of board as spacers.

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  2. The Dude

    The Dude New Member

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    Excellent idea!
  3. begreen

    begreen Mooderator Staff Member

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    Nice job, it looks good. This looks like it was done exactly as USG suggested in their old wall shield pamphlet. The furring strips are easier to cut and install and they provide a firm flat backing for the wall shield.
  4. mhrischuk

    mhrischuk Guest

    I just got off the phone with engineering technical support for USG.

    He sad NO, Durock Next Gen is not qualified and tested for over 200 deg.
  5. begreen

    begreen Mooderator Staff Member

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    True, they haven't tested it in the US, but from the documentation it appears that their Canadian arm did and endorses it for this application. If you read all the posts on this topic you will see that it's now a judgement call. After determining that unlike Permabase, the NextGen product uses perlite for the lightening filler, I have no problems recommending Durock NextGen.

    I would recommend that all write the HPBA and USG requesting testing of these NextGen products so that this issue can officially be put to rest.
  6. mhrischuk

    mhrischuk Guest

    I agree.

    The engineer basically said they no longer recommend it for stove applications but he also said it hasn't been tested.

    Looking at it closely it looks almost like solid cement I don't see any other ingredients like you do with Permabase.

    He simply said there was a major formula change and it was not tested for use in fireplaces. What gets me is all of those places out on the net that mention it. His response was yes but we do not state it in our documents.
  7. begreen

    begreen Mooderator Staff Member

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    True, they haven't tested it in the US, but from the documentation it appears that their Canadian arm did and endorses it for this application. If you read all the posts on this topic you will see that it's now a judgement call. After determining that unlike Permabase, the NextGen product uses perlite for the lightening filler, I have no problems recommending Durock NextGen.

    The supply of the original Durock and Wonderboard ran out this year. Now in the US there is no tested product. Pragmatically, the NextGen product is the only alternative we know of. It has been approved in Canada, which generally has stiffer hearth standards. I would recommend that all write the HPBA, Custom Building Products and USG requesting testing of these NextGen products so that this issue can officially be put to rest.

    Attached Files:

  8. mhrischuk

    mhrischuk Guest

    I'm using it. I just talked to another guy from there. Basically what they are saying is it won't do a good job of protecting the surface it's covering but it will not burn.
  9. begreen

    begreen Mooderator Staff Member

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    I think what they are saying is that they have not officially tested if for this purpose. In Canada, apparently they have. Take a moment to write a letter or email to them and the HPBA. It would be great to have this product certified for hearth use in the US once again.
  10. TK-421

    TK-421 Member

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    Does anyone have any updates on the durarock?

    I'm getting ready to build a heart pad for most likely an Englander 30nc. I had planned on going with three layers of 1/2" durarock to get an R-value of .75' then ceramic tiled above all screwed to each other and screwed to 3/4" plywood to protect my hardwood floors.

    Reading this article I'm now hesitant to use it as I'm worried about whether or not an insurance provider would take issue with it should a fire occur.

    Thought? Alternatives? I guess worst case with the cheap price of the 30 I could just buy an approved hearth pad but I'm a DIYer and hate to waste money on something I could do myself.
  11. mhrischuk

    mhrischuk Guest

    Ignore pretty much everything I said previously in this thread. I'm using it. I don't think there is an issue with it at all. The feeling most of us who called USG and spoke to the engineers got was that since they reformulated to the NextGen product, they simply didn't take the testing to the next level for higher temperature shielding. I think they simply aren't interested in the hearth market and it's possible liability implications in the US. Just because they don't have a sentence in their data sheet that recommends it for hearth applications does not mean it won't perform. Their Canadian leg of the company does in fact list it as a hearth substrate solution. I asked the engineer at USG if there is a different board formulation for Canada and if there is a different manufacturing plant for Canada. The answer was all of the board is the same and it's all made at the same plant for North America.
  12. TK-421

    TK-421 Member

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    I just pulled this off their site.


    The board is non-combustible and can be used in a variety of fire-rated designs. Its low thermaland hygrometric expansion help prevent finish cracking.

    They also have links, upper right, that state fire, and class A. I ant access them with my iPad so I'm not sure what they say.


    Even using them you still need 4 sheets at .25 each then your tile on top. I checked tile and got .01 R.

    That's a lot of weight to add. Seems a prefab pad might be better even though the cost is more.
  13. pen

    pen There are some who call me...mod. Staff Member

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    What the heck is inside the pre-fab pads?

    pen
  14. TK-421

    TK-421 Member

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    My very question. Space shuttle tiles. :). They are so thin. Maybe 1-2" at best.
  15. Fred61

    Fred61 Minister of Fire

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    I've used ceramic cabinet drawer pulls as spacers.
  16. ScotO

    ScotO Guest

    Hey fellas I was at Home Depot to buy some non combustible backerboard, they had both Hardiebacker and Durock.....I had bought Durock before but as I was loading this Durock on the cart recently, I noticed it had little styrofoam balls encapsulated in it.....that CANNOT be good for fire rated walls.....I imagine they did that to cut down on the weight a little, but I would not trust using that as a non combustible backer.....I held a map gas torch against some 1/2" Hardiebacker for several minutes (till it was glowing orange on one side) and you could still touch the other side with your bare hand.....I would trust the Hardiebacker board over all else esp. in a situation like mine where you are going to install tile or stone veneer.......just my two cents.....
  17. Delta-T

    Delta-T Minister of Fire

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    those styrofoam balls...could they be perlite or vermeculite? looks and tastes like styrofoam (ok, i dunno what it tastes like, but they look like styrofoam)
  18. ScotO

    ScotO Guest

    the board I was looking at (if my memory serves me rigth) looked like pink or light purple balls....not sure I ever say light purple vermiculite.....lol.....
  19. TK-421

    TK-421 Member

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    I highly doubt it is styrofoam especially since this has been approved by our northern friends.

    Put a torch to them and see if they shrivel. Highly doubtful. Be careful whenever using a torch on things that could gas. Styrofoam gives off major toxins.
  20. ScotO

    ScotO Guest

    I went with hardiebacker just to be safe.......It's listed as non-combustible and I also redneck tested it with a torch and I trust it, plus it seems to hold the cement pretty good......also easier to cut and run screws into ......
  21. Fred61

    Fred61 Minister of Fire

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    It should be pearlite. I don't think styrofoam balls would survive the mixing process. There must have been some serious stresses on the board in order to have the balls turn purple. IMHO.
  22. begreen

    begreen Mooderator Staff Member

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    It is not styrofoam, it's perlite, as already discussed in this thread.

    Durock and Wonderboard NexGen products are also listed as non-combustible.
  23. jimbom

    jimbom Combustion Analyzer

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    I do the MAPP gas torch test on things myself. Didn't really consider out gas issues. Thanks for the tip. It is nice to read so and so material is classified such and such. However, when you torture test it yourself, you know what is what.
  24. begreen

    begreen Mooderator Staff Member

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    I'm guessing Micore® SB mineral fiber board for the insulation and not sure about the backerboard. Give the folks at Yoder a call.
  25. ScotO

    ScotO Guest

    AMEN Jimbo.....I ALWAYS do the redneck stress test on items, especially if I am using them with consequences.......my friends don't call me Hearth.com Members for nothin....lol.....

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