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Cast dome with 2nd hand arch. Queensland.

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  • Cast dome with 2nd hand arch. Queensland.

    Hi Everyone,
    So after lurking here for a while I am getting closer to actually starting. So much information to absorb.
    I would like a pizza oven and decided to DIY it to save money and try a big project.

    I managed to get myself a . Some guy who demolished the rest of it saved this part of it and five flue segments and some oven tools. I thought this is a good starting point and cost AUD$250 for all of it. He had none of the firebricks...

    If you look at my pics and the link, the door is kind of a weird shape (and very rusty!) This is the extra wide model.

    I just want a normal sized oven with the possibility to cook on retained heat.

    I am on the Gold Coast,Qld. For local supply hints it would be appreciated.

    Here is my plan so far.

    Starting from the base.

    Hebel stand either on blocks or vertical Hebel board. The oven will go in a corner and may also rest on a retaining wall.

    100mm Vermiculite insulation.

    Fire bricks to cook on (not sure on available thickness in Australia seen various interstate )

    50-70mm Cast homebrew dome to save money.

    200mm/8" flue with hat. More would be good as neighbours are close and it is at the bottom of a slope.

    Door height 280mm/11"

    Dome height 440mm

    Dome internal base 880mm/34 inch (Not sure on this, seems small)

    50mm Ceramic Blanket

    100mm Vermikulite mix insulation over dome to base insulation. (not Hebel board)

    Render/mosaic.

    No roof.

    How am I doing so far?

    I am worried about joining the arch to the rest of the dome. I think some reinforcing wires had to be cut to demolish the oven. Some are present on the door frame. I presume that the arch is in position when forming the dome mold.

    Any input would be greatly appreciated!

    I have more photos I'll upload soon.


    Nicholas
    Last edited by UtahBeehiver; 07-23-2022, 07:38 AM. Reason: Removed commercial link

  • #2
    Approved, commercial link removed
    Russell
    Google Photo Album [https://photos.google.com/share/AF1Q...JneXVXc3hVNHd3/]

    Comment


    • #3
      Originally posted by Nicholasd View Post
      ​​I am on the Gold Coast,Qld. For local supply hints it would be appreciated.
      I'm not aware of any suppliers on the GC for the bricks.
      Mr Stoves in Brisy for the flue.
      Nerang Hydroponics for the vermiculite & perlite.
      jimbennett949@gmail.com is in Caboolture and can supply the bricks and insulation etc.

      Originally posted by Nicholasd View Post
      Fire bricks to cook on (not sure on available thickness in Australia seen various interstate )
      Standard 3" brick for the floor. You can use the larger 12" square brick tiles to minimise the number of floor joints. They only come in 2" which is adequate but the 3" would be better for retained heat.

      Originally posted by Nicholasd View Post
      How am I doing so far?
      Looking good.

      Originally posted by Nicholasd View Post
      I am worried about joining the arch to the rest of the dome. I think some reinforcing wires had to be cut to demolish the oven. Some are present on the door frame. I presume that the arch is in position when forming the dome mold.
      It's not a big deal as it's not a structural join. You will probably need to do some shaping of the arch tunnel to match your dome shape. Fit the tunnel through to the inside of the dome and plaster over it when you cast the dome, that will keep it secure.

      Comment


      • #4
        Thanks for the reply and information.
        Had a look at the hydroponic shop and they have different grades of vermiculite. Which is recommended?

        Which is better for insulating the slab and done, perlite or vermiculite?
        I may also need to change how thick the vermiculite is on the Hebel board as the retaining walls are about 50 mm higher than I thought. Can the vermiculite be 40-50mm thick on the slab? Or should I use cal-sil board@ 25mm?

        Thanks.

        Comment


        • #5
          The answer to some of your questions is on this thread, with detailed explanation.
          https://community.fornobravo.com/for...ion#post448045

          perlite and vermiculite are interchangeable and once mixed with cement produce the same strength and insulation value for a given equal cement addition.
          The finer the grade the more water is required in the mix to get workability. This does create a problem because the extra water, above that which is consumed by the hydration process needs to be eliminated for the insulation layer to hold heat and any steam escaping too rapidly swells and cracks the layer.
          I’ve also found a mix of grain size makes a more workable mix. This is useful for lean mixes (10:1) or leaner but unnecessary for richer mixes (5:1) or richer.
          I currently use a fine vermiculite and a medium perlite mixed 50/50 with a(10:1) mix and it requires, by volume 4parts water.
          Kindled with zeal and fired with passion.

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          • #6
            Coming back to the oven project...
            How does this idea for the base look like. The minister for planning, development and aesthetics would prefer the oven in the corner. Part of the oven will rest on the retaining wall.
            Please have a look at the mock up. The blocks are 190mm square, please ignore the full blocks at the bottom as I didn't have enough half blocks. They will be mortared in place. I will probably core fill them.
            On top of this will go the Hebel, cal sil, fire brick.

            Comment


            • #7
              I don't know how heavy your oven will be, but most are way heavier than you'd think and therefore sit on a 100mmm reinforced concrete slab. By cantilevering the slab over the piers (as shown) you can reduce the span between the piers and go a bit thinner. But remember that the strength of a concrete slab is proportional to the square of its thickness. This means a 50mm slab is only 1/4 the strength of a 100mm slab. Hebel, from my experience is not particularly strong. I used Hebel Power Panel (steel reinforced 75mm thick slabs for my mobile oven. After 8 years of use on dismantling it the Hebel looked like this. Maybe partly due to road vibration and bumps, but I didn't use it again on the rebuild.
              Judging from your pic the blocks are sitting on pavers. They may not have sufficient foundations under them, likewise the retaining wall.If you don't have block laying skills I highly recommend using masonry adhesive (eg Selleys Landscape) drill a hole in your concrete into which you can hammer a steel bar that will sit in the middle of the block cores up to the top block., mortar the first block, glue subsequent blocks on then fill the voids with concrete.

              Click image for larger version  Name:	P4060427 copy.jpeg Views:	0 Size:	30.2 KB ID:	450038
              Kindled with zeal and fired with passion.

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              • #8
                Thanks for that info.
                The oven sits on a concrete slab with a painted pattern on it.
                The retaining wall sits on foundations but I'm not sure of the quality of this work as some of the walls are not filled with gravel.
                "drill a hole in your concrete into which you can hammer a steel bar that will sit in the middle of the block cores up to the top block., mortar the first block, glue subsequent blocks on then fill the voids with concrete."
                I was wondering about reinforcing the blocks to the slab, this looks like a good solution. Would this wick moisture up through the blocks? I was going to lay plastic under the blocks to help prevent this or is this not an issue with a core filled block column this high?
                Our outdoor area is long, narrow and terraced so we don't want to take up too much room with an oven hence putting it in the corner hanging over the retaining wall. We do have some area up some stairs to a terrace above this but the ground is absolutely full of roots of now dead palm trees and isn't stable. I might think about that one though.
                I'm also thinking about pouring my own slab instead of Hebel...

                Comment


                • #9
                  I think you’d be better to get a decent bond between the bottom blocks and the concrete under them, so plastic there maybe not the best solution. I use an additive in my supporting slab that makes it waterproof, or at least reduces porosity, to prevent wicking. Another method is to use a sealer on top of the filled blocks prior to Hebel or concrete slab on top. Some sealer between the under floor insulation and supporting slab is also prudent.
                  Kindled with zeal and fired with passion.

                  Comment

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