web analytics
Yet another insulation question - Forno Bravo Forum: The Wood-Fired Oven Community



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

Yet another insulation question

  • Filter
  • Time
  • Show
Clear All
new posts

  • Yet another insulation question

    Last edited by wotavidone; 03-31-2013, 12:25 AM.

  • #2
    Re: Yet another insulation question

    They're both the same. Same insulating properties, same manufacturing processes (they are expanded minerals - popped in heat like popcorn).

    Perlite is white: it makes a good visual marker when your gray portland is evenly distributed.

    Vermiculite is said to be less dusty.

    Neither one of these is a deal killer in my book.
    My geodesic oven project: part 1, part 2


    • #3
      Re: Yet another insulation question

      I used half perlite and half vermiculite. I found this a bit easier to work with that straight vermiculite, particularly when forming/screeding the dome layer.


      • #4
        Re: Yet another insulation question

        Originally posted by dmun View Post
        They're both the same. Same insulating properties, same manufacturing processes
        Hi dmun,

        Do Perlite and Vermiculite actually have the same insulating properties?

        Forgive the question, I'm just a natural-born-fool from Gippsland, but the data I have indicates that Perlite has a thermal conductivity almost half that of Vermiculite (0.031W/m.K for Perlite, 0.058W/m.K for Vermiculite).
        The Melbourne Fire Brick Company


        • #5
          Re: Yet another insulation question

          I suspect there are a lot of variables involved with Perlite/Vermiculite/Portland insulation value. Grain size, ratio of Portland, how long it's mixed, etc.

          For our purposes (insulating under an oven floor), 4" of either material will give you satisfactory results. Is one better than another in a laboratory? Probably. Are you going to notice a difference in your oven. I seriously doubt it.

          It's like comparing flat panel TV's at Walmart. One might look a little better in the store, but either will look great in your living room.
          Ken H. - Kentucky
          42" Pompeii

          Pompeii Oven Construction Video Updated!

          Oven Thread ... Enclosure Thread
          Cost Spreadsheet ... Picasa Web Album


          • #6
            Re: Yet another insulation question

            Thank you Ken for that analysis. For our needs, there is no reason to re-invent the wheel.
            knowledge is contagious, spread the infection!!!


            • #7
              Re: Yet another insulation question

              Last time I checked thermal conductivity it said perlite was just a slightly better insulator than vermiculite, not double. I prefer to use vermiculite because it seems to mix up better and hasn't got that irritating dust that perlite seems to have. The perlite I use tends to abrade more than the vermiculite on mixing and you end up losing a bit of volume. You are not meant to mix either of them for too long, i think for this reason. Vermiculite also seems to coat with the cement a bit better, the grains of perlite are rounder and smoother and it doesn't seem to stick as well. Sorry for the extended answer. If I were making a choice between the two I'd take vermiculite.
              Last edited by david s; 06-26-2011, 01:29 PM.
              Kindled with zeal and fired with passion.


              • #8
                Re: Yet another insulation question

                For under floor insulation, you cant beat calcium aluminate board, end of story.
                OOPs that should be Cal. Silicate board.
                Last edited by Johnny the oven man; 06-26-2011, 09:27 PM.


                • #9
                  Re: Yet another insulation question

                  Thanks for your response Ken and David, and don't worry, I like extended answers!
                  The Melbourne Fire Brick Company