web analytics
2 layered firebrick oven floor? - Forno Bravo Forum: The Wood-Fired Oven Community


1 of 3 < >

Forum Page Loading Response

Forum Members:

We have received feedback regarding recent issues with page loading response time. We believe the slow response issue stems from the analytics we added with the new Forum. We are in the process of reconfiguring those elements and, after an approximate 24-hour time period for the reconfiguration to run, we anticipate a return to normal page load times. Thank you for your patience!
2 of 3 < >


Hello, Forno Bravo Community Forum members.

As many may have noticed already, the Community Forum site was briefly down today. While working on scheduled routine maintenance, we encountered an error when trying to add a software update. As the site is now back up and running, some of you may notice that some recent data has been misplaced from November 10th up to today. We are currently working on resolving the issue. The forum has full operational capabilities and we encourage all forum members to continue actively posting in the threads.

We apologize for any inconvenience that this issue may have caused you. The Forno Bravo family values each and every member of our community. If you have any issues or concerns, please feel free to let us know on our issues thread here:


Thank you for understanding.
3 of 3 < >

Forno Bravo Forum Thread Message

Hello, Forno Bravo Community Forum Members!

The Forno Bravo team has heard the feedback in regards to the community forum. We wanted to take the time to re-enforce our commitment to a fully engaged Forum with professional moderation.

Our top priority as a company is to fix all forum errors and issues that you are experiencing. As we are swiftly working on these problems, we want to say that we highly value the Forum Bravo Community Forum and every single community forum member.

We have set up this thread so that every member can address any concerns, issues and questions about the forum. Please feel free to ask whatever you would like in regards to the forum; let us know what issues you are experiencing so we can work on resolving them as fast as possible. However, we stress that we would like constructive engagement, so please be specific about the issue you are experiencing.

Thank you for all of your patience and continued support.

Link to topic: http://www.fornobravo.com/community/...with-new-forum
See more
See less

2 layered firebrick oven floor?

  • Filter
  • Time
  • Show
Clear All
new posts

  • 2 layered firebrick oven floor?

    Can anyone tell me how well two layers of firebrick on top of regular concrete will work rather than having my oven floor on top of vermiculite concrete?


  • #2
    Re: 2 layered firebrick oven floor?

    Not very well, if by 'on concrete' you mean the structural slab. For a pizza oven, firebrick directly on the structural slab is *the* formula for insufficient floor heat and/or excessive fuel consumption. You don't have to use vermicrete, but please put some form of high-temperature insulation (cal-sil, foamglas, Insblok 19) under the floor. If you're looking to build a high-mass floor for bread baking, you'll still want to isolate the heated mass from the structure of the base.


    • #3
      Re: 2 layered firebrick oven floor?

      Since this is your second thread on this, I am guessing you are still getting pushback from your contractor on insulation?

      You'd be best off with a 2 or more inch layer of Ceramic Fiber insulation and one layer of firebrick. But if you already have the 2 layers of FB in and are committed on height to something that comes in at 2.5 inches - you might try one layer of Insulated Firebrick (IFB) and one of firebrick. I think I have seen ovens built this way (Karangi Dude?).

      IFB won't work as well as other insulation - but it is probably the most efficient solution if you have to swap something out and at least it give you some insulation. Not sure if it is better or worse than Vermicrete. Probably better, as I don't think 2.5 inches of Vemicrete is enough to be very useful but that is a guess.

      but I've read enough stories here to confidently state that you absolutely don't want an oven floor with no insulation - no matter how thick the firebrick.
      My build progress
      My WFO Journal on Facebook
      My dome spreadsheet calculator


      • #4
        Re: 2 layered firebrick oven floor?

        It will not work, period. You want an envelope of thermal mass surrounded by insulation. Anything else is a waste of time and wood. Fire your mason. A good mason does not equal a good oven builder. I spend more time than I should telling consumers that the very expensive oven they had built by the low bidder is worthless (can you imagine spending 5 grand on a worthless oven?). Use the FB plans. Again, use the FB plans. One more time: Use the FB plans.


        • #5
          Re: 2 layered firebrick oven floor?

          It's really not rocket science. Masonry is a great heat sink. Said another way, it has the ability to absorb very significant amounts of energy.

          People confuse the ability of materials to act as a heatsink as being the same as being a good insulator. That is not the case. In some ways the final results are similar, but how you get there is very different.

          For example, if you build a home with concrete walls that are four feet thick, that home will generally stay cool during the heat of the day, and will stay relatively warm during the cold of night. But that does not mean that the concrete (or masonry) is acting as an insulator. What is happening is that all that masonry has a great deal of thermal mass. So at night (when it is cold outside) the masonry is radiating heat collected during the day into the structure and keeping it relatively warm...and during the day (when it is hot outside) the masonry is able to absorb a great deal of heat before the inside of the structure starts to get real warm. And before the masonry gets warm enough to start radiating a lot of heat into the interior, the sun goes down and it gets cold outside again...which tends to establish a relative equilibrium and the temps of the interior don't fluctuate all that much. As a result, the inside temp of the structure remains relatively cool (compared to the outside) during the day...and relatively warm (compared to the outside) during the night.

          But that doesn't mean the structure is well insulated. The reality is that an all- masonry structure (be it a home or oven) is not well insulated at all. It just happens to have lots of ability to soak up energy...and then radiate it back later...unless that energy has flowed somewhere else.

          So if you think of this heatsink property in the context of an oven with no insulation between the hearth and the masonry stand, the result becomes obvious. The heat in the oven is "soaked up" by the bricks of the hearth floor...and then that heat is soaked up by the masonry stand...and then that heat is soaked up by the concrete slab the stand is sitting on...etc, etc. You are left with a situation where the heat from the wood you are burning in your oven is constantly migrating away from the oven...because all of the materials surrounding your oven are really good at absorbing heat. In other words, the material is a heat sink.

          In order to have an efficient oven, you must encapsulate the oven in a layer of material which is no good at absorbing and transfering heat energy....i.e. INSULATION. You need to stop that heat from migrating anywhere so that the bricks in your oven get hotter and hotter and hotter. Materials which are good insulators are the exact opposite of masonry such as firebricks. By defintion, they are terrible at absorbing energy. They act as a wall preventing the transfer of heat energy....Just like the rubber insulation around an electrical wire acts as a wall preventing electrical energy from being transferred from that wire.

          So to sum up...it makes no difference whether you have one layer of firebricks in your floor...or ten layers. Because firebricks are not insulation. Firebricks are like batteries. They are designed to store...and then release...energy. But if there is no insulation around the firebricks, the energy just flows right out of them to the nearest area which is cooler than the hearth. In other words, the energy flows away from you hearth into your stand...and then to the earth.

          I hope that clears it up for you on a conceptual level.



          • #6
            Re: 2 layered firebrick oven floor?

            Thanks for the comments everyone... I've halted any further work and am using your comments to get the contractor to understand that insulation is a necessity.

            Thanks again..


            • #7
              Re: 2 layered firebrick oven floor?

              Can you give me the link to the FB plans?


              • #8
                Re: 2 layered firebrick oven floor?

                here they are ..
                “Never regret. If it's good, it's wonderful. If it's bad, it's experience.”


                Home Sweet Home~ Colorado Springs ~