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Dome Insulation - Forno Bravo Forum: The Wood-Fired Oven Community

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Dome Insulation

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  • Dome Insulation

    OK, I've got my dome finished and covered with a layer of high heat mortar. I have a couple questions about insulation. I have wrapped 2 insulfrax blankets around the dome and covered the blankets with wire mesh. I'm planning to put a layer of perlite/concrete over the wire mesh. Is this correct? If so, how much perlite should I buy? The instructions suggest 8 parts perlite to 1 part concrete, but a friend says he did 1/2 and 1/2. If I'm going to put a 3-4 inch layer of this concrete on, it seems like I'll need an awful lot of perlite.

    When the insulating concrete is on, do I need to put wire mesh over that before working with the stucco?

    Finally, is it necessary to insulate the entryway in this same way? Can I leave a brick finish on the entryway?

    Jim

  • #2
    Re: Dome Insulation

    I'm not telling unless you post a picture. I'm here to feed off other peoples suffering. I don't remember you suffering! I wan't to hear about cuts, falls, failures dammit!

    OK, only one answer - no wire over vermiculte/concrete needed prior to stucco. You should re-read the instructions as to your ratios mentioned about. You and your friend are both incorrect - they both might work, but not in line with the plans.
    GJBingham
    -----------------------------------
    Everyone makes mistakes. The trick is to make mistakes when nobody is looking.

    -

    Comment


    • #3
      Re: Dome Insulation

      I wondered about insulating the entryway, too, and didn't. But next time round I would.

      The disadvantage is that it gets rather hot, and as I then covered it with stucco-type stuff, its developing cracks because of the heat expansion. I think an insulated entryway would work better.

      But I don't see why you shouldn't be able to leave the the entry entirely uncovered, showing the brickwork. Or what do you others think?

      And yeah, pics would be nice... Might generate more answers, too
      "Building a Brick oven is the most fun anyone can have by themselves." (Terry Pratchett... slightly amended)

      http://www.fornobravo.com/forum/f8/p...pics-2610.html
      http://www.fornobravo.com/forum/f9/p...nues-2991.html

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      • #4
        Re: Dome Insulation

        The pics are here...
        And everywhere in this site, too. <g>
        Luis
        Attached Files

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        • #6
          Re: Dome Insulation

          How thick were your blankets?
          GJBingham
          -----------------------------------
          Everyone makes mistakes. The trick is to make mistakes when nobody is looking.

          -

          Comment


          • #7
            Re: Dome Insulation

            GJB:
            My blankets were fiberglass ones, two layers of 1/4 inches each, aproximately.

            Luis

            Comment


            • #8
              Re: Dome Insulation

              Sorry Luis,
              I should have stated the name Jim -who asked the question, but he seems to be missing in action.

              Luis - You really seem to know your bread/baking. Perhaps I didn't go far enough back in the forum to hear your whole story - who you are, what you do. Sounds like your a baker by profession.
              GJBingham
              -----------------------------------
              Everyone makes mistakes. The trick is to make mistakes when nobody is looking.

              -

              Comment


              • #9
                Re: Dome Insulation

                Ok, I've been properly chastized and I am posting pictures. I've been a leach too long. By the way, the blankets were 1 inch thick and I used two layers. A friend and I put on the portland/perlite mix and I think it worked ok. We ended up using our hands to put it on and both of our hands not feel gritty no matter how much we wash them. We have relatively thin layer on there now, but I'm going to add more this week. We used an 8 to 1 ratio, but I'm planning to do a 5 to 1 ratio for the next layer so I get a hardershell. I think I will do the entryway, but only put one layer of blanket and then the portland/perlite mix.

                The pictures are coming as soon as I figure out how to post them.

                James

                Comment


                • #10
                  Re: Dome Insulation

                  Yahoo! More pics!

                  Re: the perlite layer. If you've truely got two inches of blanket over the entire dome, that is equivalent to 4 inches of perlite/portland. 2 more inches is the minimum recommended in your case. More is better, but you should be in good shape if you get the two inches of perlcrete.

                  To post a pic, hit the "Post Reply" button then on the next page, click on "manage your attachments". You need to resize most photos to about 60% or they will not upload. Have no fear. Even if you mess it up, you can edit your post and try again without anyone knowing you made such a horrific mistake.
                  GJBingham
                  -----------------------------------
                  Everyone makes mistakes. The trick is to make mistakes when nobody is looking.

                  -

                  Comment


                  • #11
                    Re: Dome Insulation

                    Thanks gjbingham. I posted pictures by using the post photos area, but I could only do one at a time. My dome was full of big cracks, I had used some premixed high heat mortar and it didn't dry quite right. I ended up covering it all with a thin layer of refmix mortar and that seemed to seal it quite nicely. I've got the vent and chimney in, but I haven't got the pictures off my camera yet. I'll make sure I get at least 2 inches of the perlcrete.

                    Jim

                    Comment


                    • #12
                      Re: Dome Insulation

                      Thanks for posting. I saw the pics. I'd be sure to get inside the dome and fill any voids with mortar with a pointing trowel or mortar bag, just to make sure you've got the bricks locked in. It looks great. It would have been fun to watch the entire build. Sorry I bitched you out a bit. Just having fun.
                      GJBingham
                      -----------------------------------
                      Everyone makes mistakes. The trick is to make mistakes when nobody is looking.

                      -

                      Comment


                      • #13
                        Re: Dome Insulation

                        Yeah, that's what David's wife was doing inside the dome. I think we've filled in all the gaps. By the way, we're planning on using something called stucoflex for the last covering on the dome. Have you heard anything about that or used it yourself?

                        James

                        Comment


                        • #14
                          Re: Dome Insulation

                          Yep, cool pics. I saw them first off and thought "huh, when did that dome go up then?" .. till I got as far as this thread again

                          Very nice dome! I like the way you supported the last couple of rows, looks like a neat solution there.

                          Whats the stucoflex out of? I used some all acrylic stuff on mine and it worked really well.
                          "Building a Brick oven is the most fun anyone can have by themselves." (Terry Pratchett... slightly amended)

                          http://www.fornobravo.com/forum/f8/p...pics-2610.html
                          http://www.fornobravo.com/forum/f9/p...nues-2991.html

                          Comment


                          • #15
                            Re: Dome Insulation

                            Stucoflex is some sort of "elastomeric acrylic finish". You can order it in almost any color and it either trowels on or sprays on. You can go to stucoflex.com to look at it.

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