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Oven floor alternatives? - Forno Bravo Forum: The Wood-Fired Oven Community


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Oven floor alternatives?

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  • Oven floor alternatives?

    We happen to already have 160 large, low quality red bricks and 90 concrete blocks here in the Andes two hours north of Quito and workers who have built bread ovens with like material (relatively low temp and high ceilings). I have not found fire bricks. They say that concrete mixed with crushed glass is what they use. Does that sound reasonable? I had thought we could get some clay with high alumina content instead.

    I was also casually wondering why a sheet of thick steel could not be used.

    Finally, is FB insulation fibreglass board or mineral wool? For insulation I had rather envisioned using the kind of panels used to insulate vehicle engines from the passenger compartment.

  • #2
    Re: Oven floor alternatives?

    Here's a new one: crushed glass as a aggregate for concrete. Although that might be neat for a concrete countertop where you're grinding it down to expose a decorative layer, you certainly don't want it on the inside of your oven. Portland based concretes break down at oven temperatures, particularly where they are exposed to direct flame.

    Ovens have been built successfully with plain red bricks. The harder the better: you want to choose bricks that break cleanly rather than crumble when hit with a hammer. You want to steer clear of bricks with holes in them.

    The insulation boards and blankets that we use are specific refractory products. Domestic insulation has organic binders that burn and stink at oven temperatures. If you can't get refractory specialties there, you can get vermiculite or perlite from garden suppliers and make an insulating concrete out of that.

    And I know you didn't ask this, but for anyone googling "oven crushed glass", broken glass is not an insulator.
    My geodesic oven project: part 1, part 2


    • #3
      Re: Oven floor alternatives?

      The broken glass as an insulator has been used by a number of builders, I think a lot in Greece or Turkey. Although glass is not an insulator if used on its own without any cement or sand, then it is the air spaces between the broken glass that become the insulator. Typically this layer is used under the floor bricks. A local restaurant in our city here has such an oven. The builder is Turkish and his oven is huge.
      Kindled with zeal and fired with passion.