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Ceramic Spacers For Wall Behind Stove

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Gabby12, Dec 17, 2012.

  1. Gabby12

    Gabby12 New Member

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    Going to go with the 1" protected/insulated wall design behind new Castine install to keep clearances down.
    Planning to put cement board on wall studs (not needed for specs) will then add a 1" spacer of some type (thinking ceramic spacer) then another cement board with a stone veneer to finsih.

    This will be a corner of room install.

    I am building a hearth out of 2x10's and will put a 1" flag stone on top of that that the stove will sit on.
    I understand that a 1" gap will be needed on all sides (bottom, sides and top - can't do corner).

    Looking locally for 1" ceramic spacers (Home Depot, Lowes, True Value) but no luck. Stove shop sells them but they are an hour away but at least available.

    Questions:
    1. Anyone have a better idea?
    Maybe using a 1" piece of steel or alum. square stock will be easier to install and will give plenty of screwing surface for cement board that stone will be mounted on.

    2. Anyone have another place to look for these?

    3. If using these spacers, I will be putting these on my 16" on center studs from top of hearth to my mantle, what spacing should I use between each spacer going up and down stud?

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  2. begreen

    begreen Mooderator Staff Member

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    Instead of ceramic shims, cut 3" x 3' long strips of the 1/2' Durock and double them up to create your 1" shims. Attach the double shims to each stud, then attach the cement board. Be sure to leave a 1" air gap at the top and bottom so that there is good ventilation behind the wall shield.

    Skip the cement board on the wall studs if you want. It's not required.
  3. fossil

    fossil Accidental Moderator Staff Member

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    Any non-combustible material will do...doesn't have to be "ceramic". The shield can sit atop a few small 1" high spacers on the hearth (so long as there's still plenty of unobstructed space along there to let air circulate), so that's where all the weight will be borne. The wall fasteners simply serve to keep the thing vertical. Shouldn't require many. Rick
  4. begreen

    begreen Mooderator Staff Member

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  5. Gabby12

    Gabby12 New Member

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    I like these ideas.
    I guess I could use 1" pipe nipples as well with a fender washer on each end to not cut into cement board when tightening screws.
    But ripping a few pieces of cement board to make up 1" thinkness sure seems easy enough.

    Any other ideas??


    Another thing I have been thinking about is how to have a more finished look on the sides at the 1" air gap along with dressing up the 1" gap under the mantle (but understand that the mantle gap won't really be noticed as much.
    I might have a case where my end/edge on this air gap falls right on a stud.

    Can I just close off this edge or does it have to remain open?

    Any thoughts on cleaning up these gaps?
  6. fossil

    fossil Accidental Moderator Staff Member

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    NFPA 211 (into whose territory you have squarely planted yourself here) sez that for a corner installation, the top and bottom edges of the wall shields must be open for free ventilation, but you can do whatever you want with the side edges...even close them up entirely. Rick
  7. Gabby12

    Gabby12 New Member

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    "Even close up the edges?".
    Really, are you sure?
    I may be wrong but I am sure in conversation with stove shop I was told that the sides need to be open..
    Again, I may be wrong but knowing this for certain will go into wall design...
  8. begreen

    begreen Mooderator Staff Member

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    No, just the top and bottom need to be open. The sides can be sealed.
  9. FanMan

    FanMan Feeling the Heat

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    I bought ceramic spacers from McMaster-Carr once. I've also used 1" long roll pins (split pins, spring pins) which are cheaper and not as easy to crack.
  10. fossil

    fossil Accidental Moderator Staff Member

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    I'm not repeating what someone told me...I have NFPA 211 (2006 Edition) open in front of me. Page 211-43. Para. 12.6.2.4.3 reads: "Wall protectors that cover two walls in a corner shall be open at the top and bottom edges with at least a 1 in. (25.4 mm) air gap." (included is a diagram showing exactly this configuration)

    In a corner installation, the sides are up to you...leave them open if you like, or close them and finish them if you so choose. Just make sure air can enter along the bottom and exit along the top. Rick
  11. Elle

    Elle Member

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    I'm going to use the insulators I took off the floor joists that held up my knob and tube wiring. At least I hope they work...
  12. Gabby12

    Gabby12 New Member

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    Thanks for confirming Rick.
    Today I picked up my flag stone and will be using it on my 10" high hearth the I built.
    I lined the walls with Wonderboard (cement board) right to my studs.
    I understand that the wonderboard is not needed up against the studs when using a air gap design but I thought for a few dollars more why not put it on for some added protection.

    I think I am going to just rip a few strips of the wonderboard to total 1" and run that vertically up and down where my studs are.
    Have left over wonderboard and won't have to worry about getting all the 1" ceramic spacers lined up.

    When putting the R-19 insulation in the wall before putting up the wonderboard I was reading the insulation install instructions and it says that if using behind an open fire that you are to remove the paper backing (paper backing is in towards the heated room - no the outside wall).
    I did not do this but can easly remove the wonderboard I put up to do so.
    It will be harder to remove paper backing than to remove wonderboard at this point.

    I am building this addtion under a County Building Permit so have to do it by code but to honest I am not so sure the inspectors are looking to hard at things.
    Just would hate to get it built and then have an issue.
    I plan to call the County in the a.m. to see what they say - better safe then sorry.

    Any run into this situation?
  13. fossil

    fossil Accidental Moderator Staff Member

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    I wouldn't worry about that paper. That, along with the studs, of course, is the combustible material that you're going to all this trouble to protect from the appliance heat. If you're gonna go in there and remove the paper, you may as well go ahead and remove the studs. :p Rick
  14. Gabby12

    Gabby12 New Member

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    True..true....

    By the way, thanks (to all) for the help with this.
    Nothing like a good informative group of people helping each other.

    Can't wait to get a fire going in new space but want to do it right.
    Stove install is scheduled for Jan. 8th.

    Just broke ground for this sroom (24'X24' w/ a 12' high vaulted ceiling) the week before Thanksgiving and have it under roof and wrapped in house wrap (typar).
    That's excavation, foundation (4'), walls framed and roofed.

    Not too bad for an amature and a good group of friends - but I'm sore and tired and have a long way to go.
    Have a new appreiciation for those that do this for a living....
  15. fossil

    fossil Accidental Moderator Staff Member

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    Oh yeah...what is the stove you're installing? I'm assuming that you verified already that the manufacturer's installation instructions specifically say that the CTC's may be reduced by using appropriately constructed/installed shields...yes? Rick

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