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hearth thickness - 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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hearth thickness

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  • hearth thickness

    After a whole month of rain in CT we have the foundation poured. We are going to put up the walls this weekend and by next week hopefully willl do the hearth pour. I have seen 7"thick and 4"thick hearths. We were thinking of 4" with an inlaid 4" of insulting cement. Then the floor of firebrick over that. I think that should be more than adequate. Does anyone have any other suggestions that they have found from building their own?

  • #2
    Re: hearth thickness

    I think the supporting slab (what I think you are refering to as the hearth) should be 4" thick. Then the insulating cement needs another 4" for a total of 8". The word "inlaid" gives me concern. If you have a 4" supporting slab, you cannot inlay 4" of insluating concrete into it, there would be nothing to support the insulating concrete...

    If height or thickness is a concern, you can use fornobravo board (or some other fancy insulating board) in place of the insulating concrete....

    My Oven Thread:


    • #3
      Re: hearth thickness

      I guess I shouldn't have used the word inlaid. What I meant was 4" on top of the cement hearth but not all the way to the edge. Just where the dome floor will sit on. Actually I was thinking that I could get away with 4" of concrete and then 1-2" of insulation board that they use in cruciable applications. I just think that 8 inches in total plus the thickness of the firebrick floor is overkill. Of course this is my first endeavor and that is why I refer to those that have built WFOs. I don't mind the work but if the difference in heat retention is minimal between 4" and an insulating board and 4" of concrete and 4" on vermiculite and portland cement then I'd go with the former.


      • #4
        Re: hearth thickness

        Hey Mr. G,

        A 4" slab with rebar should be fine. On top of that you can either pour 4" of vermiculite concrete or use 2" insulating boards. Both will work fine thermally, so it is really a matter of choice; easy of installation and cost. In terms of efficiency, 2" of FB Board is equal to 4" of vermiculite concrete.

        I always think that the hearth only has to do two things: hold up the oven and stop heat from leaking out the bottom.

        Have fun and good luck with the weather.
        Pizza Ovens
        Outdoor Fireplaces


        • #5
          Re: hearth thickness

          Thanks a lot for the info. I agree. I think the most inmportant thing is to insulate the dome and the total enclosure between the outside walls and the blanket/refractory covered dome. Rain is coming in for next week also so we are going to have to work in between the rain drops. It's amazing how as we are building this we can taste the pizza.
          Once again thank you for the input.