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Build Question - Oven Floor Insulation - Forno Bravo Forum: The Wood-Fired Oven Community


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Build Question - Oven Floor Insulation

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  • Build Question - Oven Floor Insulation

    Hi - I am in the process of building a brick oven. The base is concrete block sitting on a slab with footings to the frost line (CT). On top of the block walls I have framed a form for a concrete slab 56"x56"x4". I will pour that slab once I fully understand how to best insluate for the oven floor.

    I have called around locally and can't seem to locate ceramic board insulation...I have read several threads about perlite and vermiculite mixes but still confused over the best method.

    I know I can't just lay the fire brick on the concrete as it will create a heat sink. What is my best option for insulation....if using vermicrete what is the recipe?

    I added a pic so you can see where the build is at this point.

  • #2
    Re: Build Question - Oven Floor Insulation

    Have you tried searching for foundry supplies, or industrial insulation companies?
    I found a few in your region that should be able to supply rigid insulation as well as ceramic blanketing.



    • #3
      Re: Build Question - Oven Floor Insulation

      At this stage of the build, I would recommend that you familiarize yourself with the 'Search' function to locate the information you need. And if you have not done so already, download the FB plans. One particularly good thread is shown below;


      The CalSil Board, FB board or anyother high performing insulation (e.g. Insulating Fire Brick) will be expensive. You can use vermicrete instead or use it to augment the insulating fire brick (more is better) but the vermicrete layer will have to be thicker (~ 2x) to match the performance of the more expensive materials.

      The mix ratio is a bit tricky too. Many people have found success with a 5:1 ratio. I started with this ratio but added lime and a bit more cement to get a nice sticky consistency. However, I was using my mixture for additional insulation on top of my ceramic blanket on the dome - so I wanted a sticky mixture to fight gravity - that shouldn't be an issue with your slab.


      PS. There are more than a few builds on this forum from CT. You might search out those to see if you can get advice on locating materials in your area.
      Last edited by ATK406; 04-24-2013, 09:00 AM. Reason: added PS


      • #4
        Re: Build Question - Oven Floor Insulation

        Thank you for your replies...I will check local foundry suppliers...do some more research on the site...(there is alot of info here...) also see if I can contact some of the local builders to see how they obtained thier materials.


        • #5
          Re: Build Question - Oven Floor Insulation

          Most concrete block suppliers will stock perlite or vermiculite since it is used to fill the cavities of CMUs. Check with them, around here in SLC it comes in 4 cubic foot bags abt. 10 bucks a bag. Also try refractory suppliers for CF board and blankets.
          Build Link............... Picassa Photo Album Link