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COB + Insulation - Forno Bravo Forum: The Wood-Fired Oven Community



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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.
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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.

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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COB + Insulation

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  • COB + Insulation


    Im interested in building a cob oven in my courtyard , have the space all picked out... Im just wondering if anyone could let me know what the external heat is like when its lit? (Or the best way to insulate to avoid it getting hot on the outside when lit) ....

    Ive seen some ovens built of refractory mortat etc and they cover them in ceramic fibre blankets to insulate and keep the outside cool , is that a possibility with cob too??

  • #2
    Re: COB + Insulation

    I have two neighbors with cob WFOs. Depending upon how long they are fired the outside can become warm to hot to the touch. I have not seen either of the WFOs get so hot that a momentary contact would sear or even burn to the extent of a blister. Not saying that one couldn't fire them long enough and hot enough to cause such to occur or that one couldn't be constructed thin enough to cause issues, just that in the normal course of events I don't think it is a major problem.

    As for using insulating cob ovens with ceramic fiber blankets: One of the major pluses of a cob WFO is their relative low cost to build. They are rather delicate (at least in comparison to a brick WFO) and so depending upon the use and abuse they need rebuilding occasionally. So, to use an expensive insulating blanket on a inexpensive WFO is sort of an oxymoron, especially as reusing the blanket when rebuilding the WFO would be problematic. Would one consider putting a thousand dollar paint job on a hundred dollar car?

    Hope this helps,


    • #3
      Re: COB + Insulation

      Thanks for the reply and the info.

      I guess my major concern and reason for asking about the outside heat is the positioning of where I want to put my oven.

      My yard is quite small so don't have as much of the luxury of positioning that I would like to have.... I want to construct a 1m x 1m brick column to build the oven on ... Only thing is it will be right between a pine deck and a colorbond (metal) fence.... Do you think the heat from the oven is going to cause any major dramas with either of these structures?


      • #4
        Re: COB + Insulation

        It's best not to have the mouth of your oven face the pine deck. These things do spit cinders when you're firing them up, and you may have better things to do than stand guard with a spray bottle in the time it takes to heat it up.
        My geodesic oven project: part 1, part 2


        • #5
          Re: COB + Insulation

          Depending upon what the distances are when you say "right between". I don't think there would be any problem with regard to radiant heat from the sides or back of the WFCO (Wood Fired Cob Oven) if a reasonable distance is maintained (think along the lines of building code distances). However, with regard to the radiant heat and the possibility of embers and sparks out the front I have more concern if it were to face toward the pine deck and the distance was short. But, of course one would think that you would want the WFCO facing toward the deck for access etc and so I would take some sort of precautions regarding sparks etc. if you are going to have the WFCO close to the deck.

          The fire and radiant heat out the front of a WFCO is impressive due to lack (usually) of a chimney when firing up.

          Hope this helps,