1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)
    Caluwe - Passion for Fire and Water ( Pellet and Wood Hydronic and Space Heating)

Micore Board Strong Enough?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Rob From Wisconsin, Sep 4, 2012.

  1. Rob From Wisconsin

    Rob From Wisconsin Minister of Fire

    Joined:
    Nov 20, 2005
    Messages:
    531
    Loc:
    East-Central Wisconsin
    Looking to "beef up" my hearth.
    Is Micore board strong enough to support my 300lb+ stove
    without breaking? I've never worked with the stuff before,
    so I'm a bit "green" to it. Thanks!

    Helpful Sponsor Ads!





  2. DAKSY

    DAKSY Patriot Guard Rider Staff Member

    Joined:
    Dec 2, 2008
    Messages:
    4,891
    Loc:
    Averill Park, NY, on Burden Lake II...
    Nope. It's pretty fragile. The BEST thing to do is to sandwich it between Dura rock or hardi backer (top) & Plywood (bottom), at least if you intend to move it at a future date. If not, you can probably omit the bottom plywood layer & screw right through the top layer to the floor under the Micore. Stone or tile or whatever can then be applied to the top layer with thinset...
  3. Rob From Wisconsin

    Rob From Wisconsin Minister of Fire

    Joined:
    Nov 20, 2005
    Messages:
    531
    Loc:
    East-Central Wisconsin
    Thanks for the quick response.
    Sounds like I could just place Cement Board on top of it,
    and that would be OK??
  4. DAKSY

    DAKSY Patriot Guard Rider Staff Member

    Joined:
    Dec 2, 2008
    Messages:
    4,891
    Loc:
    Averill Park, NY, on Burden Lake II...
    Probably, but that depends on whether your stove has legs or a pedestal. The legs may eventually push right thru the concrete board. You have a heavy weight distributed over a very few square inches of surface. The board is meant to be a backer not a finished surface. I'd at least try to find some casters, tiles or stone pieces to distribute that weight over a greater surface area. Your call.
  5. Wood Duck

    Wood Duck Minister of Fire

    Joined:
    Feb 26, 2009
    Messages:
    4,037
    Loc:
    Central PA
    It depends what is under the cement board, i think. With a suitable support under the cement board and tile or something like that on top, yes, the cement board will be fine.
  6. dorkweed

    dorkweed Guest

    I built my raised hearth out of 2x4's (about 12" on center), 1/2 plywood over that, and 2 layers of 1/2" Micore over that, 1 layer of 1/2 Durock next gen over that and then my mortar and procelain tiles. The 13NC goes about 300lbs., and my hearth takes it no problem. No sagging or deflection when stepping on it that I can see or feel.
  7. DAKSY

    DAKSY Patriot Guard Rider Staff Member

    Joined:
    Dec 2, 2008
    Messages:
    4,891
    Loc:
    Averill Park, NY, on Burden Lake II...
    He's putting the cement board on the Micore....There's not much support from the Micore unless it's on a solid surface. No way would I install Micore on a 2x (anything) framework without ply below...
  8. Fire Breathing Dragon

    Fire Breathing Dragon Member

    Joined:
    Feb 26, 2012
    Messages:
    82
    Loc:
    Carroll County, MD
    I built a hearh ealier this year with Micore. Installed it directly over the OSB subflooring, then a layer of sheet metal to disperse the heat, then topped it with 1/2 cement board staggering the seams. On top of the cement board I installed ceramic tile in a bed of thinset. My stove is the VC encore on pedistal legs and had no movement since installed in Feb this year. As said before Micore has no structural strength, it is like using a sheet of drywall which can crush ever so slightly but with good cement board, tile, and thinset above it should disperse the weight... Good luck!
  9. mepellet

    mepellet Minister of Fire

    Joined:
    Aug 10, 2011
    Messages:
    1,864
    Loc:
    Central ME
    How about installing 2 layers of micore directly on the subfloor and then tiling directly on top of that? What is the recommended way of attaching micore to the subfloor?
    Is the layer of sheet metal and the cement board necessary?
  10. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    45,989
    Loc:
    South Puget Sound, WA
    Uh, uh, no way. Micore is not a suitable substrate for tiling. Put a top layer or two of cement board on top and screw through the layers to attach to the floor. Most cement board mfgs recommend a screw every 8".
  11. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    45,989
    Loc:
    South Puget Sound, WA
    Rob, if you have a pedestal base, maybe. But if the stove has legs and for a more durable surface at least put a sheet of 24 or 22 ga metal on top of the cement board and screw it down at the corners.
  12. mepellet

    mepellet Minister of Fire

    Joined:
    Aug 10, 2011
    Messages:
    1,864
    Loc:
    Central ME
    Thought so. Just wanted to check since I have not bought the Micore yet. I had no idea what it was like.
  13. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    45,989
    Loc:
    South Puget Sound, WA
    It is a soft spongy material, kind of like what you would find in acoustic tiles. It's used for sound deadening in office cubical dividers.
  14. mepellet

    mepellet Minister of Fire

    Joined:
    Aug 10, 2011
    Messages:
    1,864
    Loc:
    Central ME
    Ok. Thanks again begreen! I think I'll go with:
    Tile on top of 1/2" cement board (R0.39) on top of 1/2" micore (R1.03) on top of the existing subfloor (diagonal boards on joists) for a total of R1.42 plus whatever tile is worth (not much I assume)
  15. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    45,989
    Loc:
    South Puget Sound, WA
    Tile is not worth much for insulation unless very thick. What stove is going on top of this?

    Nevermind. I see you have your own hearth building thread going.
  16. mepellet

    mepellet Minister of Fire

    Joined:
    Aug 10, 2011
    Messages:
    1,864
    Loc:
    Central ME
    Don't mean to hijack the thread. But now it's a napoleon 1100c but I want the hearth to be as flush as possible with the existing flooring and for it to have as much R value as possible to accomodate a large variety of stoves should we decide to replace the 1100c. I had started a thread earlier today about the hearth build.

    http://www.hearth.com/talk/threads/new-hearth-build.109188/

Share This Page