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Best fix for an uneven hearth? - Forno Bravo Forum: The Wood-Fired Oven Community



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Best fix for an uneven hearth?

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  • Best fix for an uneven hearth?

    I ran out of vermiculite at the very end of pouring my hearth so the top surface is uneven. Most areas are off by inch off but some areas are off by inch. I started to sand it down but determined it was way too much work to get it level. I am wondering if I should level it out with more vermiculite/portland cement mix or a thin layer of mortar or if the fire clay/sand mixture will be enough to make it level and sturdy.

    Any ideas/tips are much appreciated.



  • #2
    Re: Best fix for an uneven hearth?

    Hi Jeremy,

    Had a similar situation only not as deep as 1/2", but you should be fine with the fireclay/sand mix. Do it in two layers, first all the deep spots and level those off with a straight edge and wait till it gets a little stiff. Then do a second thin layer over the whole floor and start putting down the bricks.

    Doesn't sound like a leveling layer of Vermucrete is neccesary. Do you have any pictures?




    • #3
      Re: Best fix for an uneven hearth?

      I was still able to sink a fingernail into my fireclay/sand mixture a week after I had spread it on my slab. If it were me, I would follow Kurt's advice about first spreading the mixture around to even things up, except I would add 1 part portland cement to it and that would set it up pretty quickly. Then I would add the usual fireclay/sand on top of that to even the bricks up.



      • #4
        Re: Best fix for an uneven hearth?

        Thanks Guys!

        I have attached some pictures for review. As you can see the middle is somewhat level it is the outter areas that fall off and is the problem.

        Putting down two layers sounds like a good idea. I think adding Portland in the first layer will help firm it up. Should it be equal parts Portland, fire clay, and sand, correct? I figure I will level the first layer then come back in a few days and do the normal fire clay/sand mixture and lay the cooking floor.

        Any other ideas?


        Attached Files


        • #5
          Re: Best fix for an uneven hearth?

          Should it be equal parts Portland, fire clay, and sand, correct?
          What's the portland for? I think your normal mixture of half fireclay/half sand will work just fine. You can use it either wet, trowled on with a notched trowel, or dry, and wet your floor once you're happy with the level.
          My geodesic oven project: part 1, part 2


          • #6
            Re: Best fix for an uneven hearth?

            Since the only "load" on this material is dead weight, the Portland won't really add much to the structure. Even if this 1/2" layer is 'soft', it won't go anywhere, and it's only real job is to fill space, not compact, and provide a level surface for the fire brick. And after a few fires, the clay in the mix will be pretty darn hard..

            Another opinion!