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My hearth mortar job was a failure,,,,Uggg!

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by charly, Sep 24, 2012.

  1. charly

    charly Guest

    Don' t know where I went wrong. Stone place I bought my brick from gave me S type mortar. 12 hours later I could just pull have of the bricks loose. Mortar was rock hard on the back of the brick. Almost like it didn't stick that well to the Durock board. Brick box showed to only use lath on an exterior wall. So now I pulled everything back off the hearth pad, cleaned the pad and am tossing all the brick as there is no way to get that mortar off the backs. Kind of disgusted at this point. I guess maybe I should have just used thin set instead. I want to make the second time count. Mix was good, only thing I can think of is I didn't work the bricks into the mortar, enough. Any ideas as to make a second attempt good would be appreciated.

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  2. ScotO

    ScotO Guest

    It can be hard to install mortar directly on Durock. Did you pre-moisten the Durock? I know if you try to put mortar on a really dry surface, the surface will suck the moisture right out of the mortar. You don't want it to be soaking wet, but it pays to keep a spray bottle full of water while doing your brick or stone, spritz some water on the area your working prior to each stone or brick you lay. Even better yet, install something expanded metal lath and a scratchcoat of mud down prior to installing your brick. Still, whatever substrate you use, be sure to dampen it before installing your brick. Makes the bond a lot stronger
  3. begreen

    begreen Mooderator Staff Member

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    Good suggestion. Consider trying Scotty's method on a piece of scrap board.

    Just to clarify, are these full bricks, half-bricks, or brick tiles? If half bricks or brick tile, I would try some latex modified thinset on a sample board and see if that works better.
    raybonz likes this.
  4. charly

    charly Guest

    Be Green, I'm using real used cut brick, 1/2 inch thick. Scotty, about half way through I started wetting the Durock with a spray bottle. I think my problem was using the 1/4 inch notched trowel, I scraped both the board and the back of the bricks with the trowel after applying mortar. Now I'm thinking of just buttering the the board and the brick , that giving me a better amount of mortar contact. I worry about the lath having movement even after coating it with mortar, once the weight of the stove is on it.. Just one more thing to give with the stove on and let the joints crack. Maybe I'm wrong? Do you think thin-set will allow a better bond then the S mortar ? I'll have to try a piece of brick on an extra piece of rock board. Man I couldn't believe I was taking the whole thing apart! Another question, once grouting all the joints, will that strengthen the bricks to the board at all? As I said before , some were solid as far as bonding and others pulled off . As far as wetting the board, would you spray the whole board ahead of time and wait 5 minutes before starting or just keep soaking it as you go? I know my mortar was nice and wet . Sorry for all the questions.
  5. Beetle-Kill

    Beetle-Kill Minister of Fire

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    Over the last few weeks I've used about 1600lbs of S type mortar, with another 800 or so to go. What Scotty said works, misting the board and brick prior to "buttering" it is the way to go. And when installing on a verticle surface, don't spread it. Take your trowel and flick it, slap that mortar onto the wall like you're trying to fling it off the trowel. Then spread it, then fling some more. don't know why but it really sticks by doing that.
    before you toss your brick, do you have a grinder? If so, pick up a diamond wheel and some dust masks, should cut that mortar fairly quickly.
    Just do it outside.
    ScotO likes this.
  6. ScotO

    ScotO Guest

    you don't want to use a notched trowel. I wouldn't even worry about putting a thick layer of mortar on the board at all. Maybe smear (and I mean really smear) your mortar in a thin coat over the Durock, only doing a small section at a time. Butter each brick with a nice, thick layer of mortar and wiggle each brick onto the surface of the Durock.......don't get ahead of yourself, only smear mortar on small sections of your board at a time, so as to not let it dry out too fast.

    That expanded metal, when impregnated with mortar, will not move at all once it sets. My hearth in the kitchen has NO board under it at all. I put down tar paper, built up a form in the shape of the hearth, screwed my expanded metal lath to the sub-floor, and poured 1 1/2" of concrete right on top of it. Layed my tiles right to the concrete with thinset mortar. No cracks, looks like I did it yesterday, and I did it almost 6 years ago.

    No. You need mortar. Type S is fine.

    Grouting is what makes the piece you are doing a solid unit, so yes....it will greatly strengthen the bricks. I hung real stone veneer on my walls, all through the house, and it is heavy stuff. Never lost a single stone, still tight as it was the day I put it on. And I used Type S mortar.

    No, just spray right before you lay. not soaking wet, just damp.

    That can be a problem. Only make your mortar the consistency of mashed potatoes. Too wet and the stuff won't stick right.

    What percent are you mixing the type S with sand? I go almost 3-to-1 with my mix. Works fantastic.
    f3cbboy and Backwoods Savage like this.
  7. ScotO

    ScotO Guest

    OK, two suggestions. First off, I just noticed that the bricks you are using are cut bricks 1/2" thick, I would reuse all that brick. Don't even bother taking the mortar off, you can reuse those bricks with the mortar on them still, if you can live with your hearth being a half inch thicker. So long as the mortar is set really good on the back of those bricks, get a dry diamond blade for your 5" angle grinder and cut grooves, around 1/4" deep, into the mortar on the back of those bricks. Then, moisten them (just as you would the substrate, with a spray bottle) and re-butter them. Apply them to the hearth just as you would have originally. You should be fine, and you'll end up with another 1/2" worth of firestop under your stove......
    PapaDave and Backwoods Savage like this.
  8. charly

    charly Guest

    Think that was one problem, I was just pressing the bricks down into the mortar, not wiggling them. I started doing that at the end and could feel a difference in them being seated. As far as cleaning over a 100 bricks, I'll see how it goes. I do have a diamond wheel I was using to cut my shorter bricks for every other course.

    I'm using S type quickrete mortar. I think I didn't have the board wet at the beginning and not enough mortar on the back of the bricks. plus no wiggle, just pushing straight down.
  9. charly

    charly Guest

    Good idea! Thanks Scotty!
  10. ScotO

    ScotO Guest

    Is that mortar pre-mixed or do you have to add sand to it?
  11. charly

    charly Guest

    Premix
  12. ScotO

    ScotO Guest

    OK, then you don't have to worry about adding sand. Just keep using the mix, but don't make it too wet. And don't forget the pics, brother!! We THRIVE off of pics......LOTS AND LOTS OF PICS!
    PapaDave likes this.
  13. Jags

    Jags Moderate Moderator Staff Member

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    "Twist" them in place, or a good wiggle will get the job done. Wetting the backer board is only that. It will not absorb water, so "letting it soak" has no advantage.
    Backwoods Savage and ScotO like this.
  14. charly

    charly Guest

    OK Thanks Jags!
  15. ScotO

    ScotO Guest

    Charlie, would that be an Esse Ironheart I see in your avatar pic? YOU LUCKY BASS TURD! I absolutely LOVE that cookstove! Don't mean to derail your hearth thread, but I just had to compliment on it. How do you like it for cooking/baking/heating?
    charly likes this.
  16. ScotO

    ScotO Guest

    Durock will absorb moisture alot like concrete, whereas the Hardibacker stuff will barely absorb it at all. Just a spritz of water on the Durock before you apply the cement usually helps it stick. And if you use a finishing trowel and REALLY smear a thin layer of cement on the Durock right before you butter up your stone/brick and install it, it'll stick really good.
    Jags likes this.
  17. charly

    charly Guest

    Yes Scotty, that's Miss Esse , as myself and friend who has one call it. It's a great stove. It cooks great and then you realize, wow it's heating us at the same time. Well worth the money . Overnight burns too. For the first 3 months , I would look up the Tee outside to check the chimney, it still had a shine to the inside, I couldn't believe it. Has a secondary air control at the top of the firebox. I shut the bottom main draft once it's going and just run the secondary air. Puts out some smooth comfortable heat with that big cast iron top. Over 700 lbs. 2 friends lifted her up waste high and carried into my house . Wish I took their picture carrying the stove.
    ScotO likes this.
  18. paredown

    paredown Member

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    You can also clean mortar off brick with a good crack with a sharp brick chisel and heavy hammer--support the brick and get the chisel placed just so at the junction of brick and mortar and give it a good hit. You'll break some, but personally I hate cutting wheels and all the dust they produce.
  19. charly

    charly Guest

    Thanks for the tip.
  20. charly

    charly Guest

    Scotty, here's where I'm at;). Nothing special, wife didn't want 45'd corners, old house she thought square looked more old school. Sorry no pictures of me disgusted ripping all the first brick job back off:). 100_7155.JPG 100_7157.JPG 100_7163.JPG 000_0219.JPG
    ScotO likes this.
  21. Jjm457

    Jjm457 Member

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    I'm pretty sure that Durock has two different sides to it, at least the original Durock did (not sure about the next gen Durock) Check the label, one side is for mortar and the other for mastic. The best way to go is using the polymer additive directly to the thinset instead of a water mix. Also, 1/4 inch notch may not be enough for a 1/2 stone or tile.

  22. ScotO

    ScotO Guest

    That looks great to me, so far. Jjm may be right on the next gen Durock. Not 100% sure though. That's gonna be a nice looking hearth, cant wait to see it when finished!
  23. Jags

    Jags Moderate Moderator Staff Member

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    Hmmm...never heard anything about the "two sides" to the Nextgen...

    Edit: - just confirmed with USG (hey, I buy over 30 mill a year from them, I gotz a bat phone to the Commissioner:) ). The OLD Durock did have specific sides. The Next Gen does not differentiate. There is a texture difference due to the making process, but either side can be used for "whatever".
  24. ScotO

    ScotO Guest

    All the stuff I've ever used was the old style Durock. No idea what the next gen stuff is about. As a general rule, if I'm doing a mortar to hang or set stone/brick, I pour the pad rather than using backerboard. Just seems to be easier to work. If you DO use the poured pad method, be certain to put metal lath or screen down first. That'll keep it from cracking......
  25. charly

    charly Guest

    Only thing I read was to put the smooth side down which I did.

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