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Oven Expansion and expansion joints?

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  • Oven Expansion and expansion joints?

    Hi All,

    I'm confused because I feel like I see conflicting information from different sources and I'm not sure the best way to handle the construction details.

    The FB modular instructions say to place the dome pieces with up to a 1/2" gap between them. But then they fill the gap with refractory mortar? There's no more expansion joint. Does this mortar just crack at some point? Maybe people never see it because it's hidden by the outer layers? Has anyone had to take apart their oven for any reason (gasp) and seen what the inner shell looks like? I'm assuming you have to mortar over the joints, but it's no longer an expansion joint. I don't believe that the gap at the inner surface does much for you.

    If you mortar the floor tiles into place, I'm assuming the mortar underneath will crack at some point as well?

    I have a modular kit (Cuore 1000) and the dome pieces sit on top of the floor pieces. The instructions tell me to mortar the bottom of these pieces in place on the floor. The Melbourne Firebrick instructions say to do the same thing with their modular kit. Should I mortar them in place or not? Can I get away with not doing it? Again, I'm assuming there is no room for expansion and this mortar will crack.

    The instructions that I have as well as the Melbourne Firebrick videos say to "grout" in between the floor tiles with mortar after you place them. Is this a mistake? Again, no room for expansion. Can I safely leave the gap or should I mortar in between?

    I've never built an oven before, but I'm coming to the conclusion that no matter what I do these joints are going to crack.... but it doesn't mean I shouldn't mortar them.

    After reading posts on this forum (which is great by the way), it seems like it's a best practice to place expansion joints between the inner and outer shells. The ceramic fiber blanket takes care of almost all of the expansion concern except the front of the oven. I'm planning on putting a decorative brick arch at the front and maybe a granite landing. My thought is that I should put a gap between the oven floor and the landing? Also between the front face of the oven and the decorative brick arch? The question then is what to put in that space? Ceramic fiber cord? I think I saw a post by david s where he used an 8:1 vermicrete mixture - is this meant to be a "crumple zone"?

    Thank you for the insight.

  • #2
    After months of searching and scratching my head with the same dilemma I find your post. I too have the Cuore oven. I put it together a few weeks ago and applied mortar to floor pieces as I installed the dome pieces. I went too close and had a 2" gap on the last piece. I quickly took it apart and tried again with a larger gap between the dome pieces and no mortar between dome and floor. A few weeks later I could see right through the gaps from the inside looking out. So for the second time I took apart the oven. The refractory mortar I used came right apart (I have not fired yet) and washed off. I am curious what you ended up doing. Did you use refractory mortar or refractory cement? If you don't mind sharing your experience I'd appreciate it greatly. Thanks!