web analytics
fibre blanket under vermiculite heart? - Forno Bravo Forum: The Wood-Fired Oven Community

Announcement

Collapse

Forum Issues Update

We are continuing to work diligently to resolve the issues currently being experienced with the PhotoPlog. Thank you for your patience!
See more
See less

fibre blanket under vermiculite heart?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • fibre blanket under vermiculite heart?

    I'm looking at a kit oven with a 50mm hearth fabricated from fire clay. The supplier told me to put down a 100mm vermicrete slab underneath the base. Is this the best type of construction? They supply fibre blanket for insulating the dome. I'm wondering should I put a layer of his underneath the vermcrete slab or would this be pointless?
    Thanks

    Richard

  • #2
    Re: fibre blanket under vermiculite heart?

    The blanket is for insulating the dome - it will not support the weight, they make an insulating board for that. 100mm of vermiculite would work, personally I would kick it up to 127
    Check out my pictures here:
    http://www.fornobravo.com/forum/f8/les-build-4207.html

    If at first you don't succeed... Skydiving isn't for you.

    Comment


    • #3
      Re: fibre blanket under vermiculite heart?

      Originally posted by Les View Post
      The blanket is for insulating the dome - it will not support the weight, they make an insulating board for that. 100mm of vermiculite would work, personally I would kick it up to 127
      Thanks Les, ill just increase the vermiculite layer then. Is it simply a case of 'the more the merrier'? Should I put in a 150mm vermicrete slab?
      Also, does this stuff strengthen as quickly as concrete? Can I start building on it the day after I pour?

      Comment


      • #4
        Re: fibre blanket under vermiculite heart?

        Originally posted by RichC View Post
        Thanks Les, ill just increase the vermiculite layer then. Is it simply a case of 'the more the merrier'? Should I put in a 150mm vermicrete slab?
        Also, does this stuff strengthen as quickly as concrete? Can I start building on it the day after I pour?
        Insulation never hurts - there will be a point of no return but I have no clue where that is. I did not use it for my base so I need to defer the answer for someone who knows for sure. I would guess that you would want to wait about a week before you start building on it - it's pretty weird stuff to work with.
        Check out my pictures here:
        http://www.fornobravo.com/forum/f8/les-build-4207.html

        If at first you don't succeed... Skydiving isn't for you.

        Comment


        • #5
          Re: fibre blanket under vermiculite heart?

          Hey Rich you asked if the vermicrete would strengthen like concrete which leads me to belive you may just freak out when you start mixing and placeing it.This will not at all be like concrete.Think off it like a million little styrafoam beads held together with mud.When you mix it for the first time you'll think "This cant be right"but it works.It will fell spongy and strange.Win it dries its still actually soft or atleast soft compared to concrete.By the way its mixed by volume so get you a one gallon bucket to load your wheel barrow.8 buckets vermiculite to 1 bucket of mixed portland or whatever ratio your directions call for.Mix gently with a spade shovel and your gold..


          Bill

          Comment


          • #6
            Re: fibre blanket under vermiculite heart?

            More is better, I have 2.5 inches of 7-1 vermicrete under 2 inches of ceramic board and my wood bin ceiling still gets to 25-50 degrees over ambient air temp. I wish I had gone with another 2 inches of insulation, either ceramic or vermicrete. In the winter it can be 100F over ambient.... -20F outside and +80 under the oven.
            Chip

            Comment


            • #7
              Re: fibre blanket under vermiculite heart?

              Thx guys. Tx, ill try not to freak out. Might try an get some vermiculite mixed today. I intend using 6:1 by volume in the base, mixing dry vermiculite and dry cement and then wetting. My hearth insulation will be 135mm thick. Thanks for heads up. It's quite windy here and the vermiculite seems quite light. My biggest worry will be tring to stop it blowing away I think.

              R

              Comment


              • #8
                Re: fibre blanket under vermiculite heart?

                [ATTACH][/ATTACH]The thickness of vermicrete and efficiency conforms to the law of diminishing returns. 100 mm is normal, a little more is slightly better, but a lot more of little extra value. Most builders have found a 5:1 ratio about best. More cement will make it stronger but less insulating. Less cement will make it more insulating but weaker.
                Vermicrete takes up lots of water, way more than is required for the hydration process, so keeping it wet is not generally necessary, depending on the weather. Removing the water is however another problem. I did some tests about this that show the water removal is pretty slow. Once you've covered it over the weather won't dry it much and it will take lots of fires to eventually dry it.
                Attached Files
                Last edited by david s; 08-08-2013, 12:20 PM. Reason: Typo
                Kindled with zeal and fired with passion.

                Comment


                • #9
                  Re: fibre blanket under vermiculite heart?

                  Hi David, your zipfile appears to be corrupted. Could you re-upload please?

                  Thanks

                  Richard

                  Comment


                  • #10
                    Re: fibre blanket under vermiculite heart?

                    Originally posted by RichC View Post
                    Hi David, your zipfile appears to be corrupted. Could you re-upload please?

                    Thanks

                    Richard
                    works ok for me. Try this one.
                    Attached Files
                    Kindled with zeal and fired with passion.

                    Comment


                    • #11
                      Re: fibre blanket under vermiculite heart?

                      or this one may work better for you.
                      Attached Files
                      Kindled with zeal and fired with passion.

                      Comment

                      Working...
                      X