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FB Board under floor AND dome? - Forno Bravo Forum: The Wood-Fired Oven Community



I'm Peter Reinhart! Ask Me Anything! Monday, February 15, 2016 7:00-8:00 pm EST

To kick off our AMA feature, we have invited author, chef and master bread maker and host of Pizza Quest, Peter Reinhart, to be our first host! Peter will be in the Forum on Monday, February 15th, from 7:00 - 8:00 pm EST. If you are unable to be online during the live session, you can post your questions in the sticky post. Peter will answer those questions during the live session on February 15th. You can view Peter's answers to your questions as well as what happened during the live session in the session thread.

Ask Me Anything New Forum Feature

You will notice a new forum at the top of the main page called, "Ask Me Anything". This forum will be used for live one hour "Ask Me Anything" (AMA) sessions hosted by people who are knowledgeable in different areas pertaining to wood fired ovens. How it works:
- Each AMA will have a "sticky" thread where the community can post questions they would like answered during the live session. This will allow everyone to participate even if you can't be online for the live session. These questions will not be answered by the host until the live AMA; if you need an answer quickly, you should post it in the appropriate Forum area for the community to respond.
- Another thread will be posted for the live AMA. Registered users who are logged in during the live session can interact with the host by asking questions and receiving responses.
- The live thread will remain in the AMA forum to view after the session.

We hope you enjoy this new feature! Please let us know if there is a topic that you'd like to have as an AMA and we'll look for a host!

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FB Board under floor AND dome?

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  • FB Board under floor AND dome?

    I just received my FB board and I am ready to build my Pompeii oven, finally.

    However, the FB board seems softer than I expected. I am not sure that this material will support the weight of the dome and the vent. Maybe it is only supposed to be under the floor and the dome rests on the concrete foundation.

    Any insight would help, I am ready to go if I can figure this out...

  • #2
    Re: FB Board under floor AND dome?

    The board can support the weight. You need the dome insulated from the hearth. When you say softer, what exactly do you mean? In no way is the stuff like concrete but it should be fairly firm.
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    • #3
      Re: FB Board under floor AND dome?

      By soft I meant that my finger can leave an imprint. I did not expect it to be like concrete. Not exactly sure what I expected, but the dome will probably weight a half ton or so and all that weight will be on the 4 1/8" ring of my fire brick. Just didn't seem logical to me.

      Did you use FB board without any issues?


      • #4
        Re: FB Board under floor AND dome?

        The board you got will be fine. I'm sure the FB folks would not send out an unsuitable product. Yes, the board will seem too soft to support the entire weight of your oven, but this is a common perception. Just make sure you don't let any portion of your dome (and entry) come into direct contact with anything other than insulation. Any contact will cause heavy losses of heat through conduction which translates into excessive wood requirements during heat-up and rapid loss of residual heat.


        • #5
          Re: FB Board under floor AND dome?

          I thought that contact with the concrete might act as a "thermal short", but I was more worried about the weight.

          Since it looks like its OK I will proceed. Thanks

          When you lay down the FB board should you level with sand or fire clay?
          Maybe the bricks should be leveled on top of the FB board?

          I noticed that the fire brick thickness seems to vary enough to show lips...


          • #6
            Re: FB Board under floor AND dome?

            The recommended solution is to level the bricks on the board with a 50/50 blend of fine sand and fireclay, although there's nothing that says you couldn't fill voids between the board and your concrete suppoort slab with the mix as well.

            You can mix water with the blend and (notched) trowel it on wet or do what I did: just trowel on dry and tap the bricks with a hammer until you're satisfied. If you wet the bricks from the top it will set your 'mortar' underneath.

            You may want to level your floor bricks with a slight slope towards the entryway so if any water gets in it will run out.


            • #7
              Re: FB Board under floor AND dome?

              Thanks for the pointer Gianni.

              I'll see how much flex the FB board has when I lay it down and then I can determine if I need to level underneath it. Since I will be using the FB board I'll probably mix in very little water as to not saturate the board. Just enough to get the mix to flow.

              I've spent years thinking about this build and just as many getting my site ready. Now that I am finally at the point where I can build my dome I don't want to leave anything to chance.

              Wish me luck