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several dumb questions, if I may... - Forno Bravo Forum: The Wood-Fired Oven Community



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several dumb questions, if I may...

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  • several dumb questions, if I may...

    Hello there!

    Still wading thru the info from the forno bravo site and making notes of key ingredients. Also checking out the (few?) Australian suppliers of refractory stuff.

    One of these has a materials list for a circular dome pizza oven measuring 100 cm in diameter and quotes $A3.50 ea. for the medium-duty bricks (there are no low-duty bricks listed).

    My question: the list states the dome will need 67 of their arch 75/63 bricks and 33 of their arch 75/57 bricks, plus 25 base bricks - what do these fractions refer to? (I guess I'll also ask the company when they're open again tomorrow...) Perhaps they make the bricks the right shape for building a cupola? This would be just to beaut for words, saving all the cutting and splitting of bricks (not something I'd look forward to at just over 70!)

    Another question to the wise:
    For a round oven, why not make the hearth (and by extension the slab) round also? I'm thinking of using the stiff clay soil on our property to "form up" for the base concrete by just digging a circle etc.

    Then I would build blockwork walls as described for the Pompeii model - except mine would radiate in quadrants from the centre! This will leave me with four open spaces to put the cut timber in... I may even leave the walls short at the centre, i.e. unconnected, so that the little poisonous black snakes (one just killed a young hen who thought she'd found a nice big worm!) can slither away in any direction when disturbed...

    Then the round hearth slab would be cast on top of the four radial block walls. I guess the radial walls would be even better at holding up the hearth because than the rectangular stand as there's more support where the weight is...

    I'm certain to have more questions once I really get going... can't wait to start! And all this because my wife's fancy s/s electric oven that I'd been keeping going for the past 13 years has finally conked out and we have to BUY 'bread' instead of baking our own sourdough loaves...


    "I started out with nothing, and I've still got most of it"

  • #2
    I like the idea of a round stand and hearth. There are a number of them in the photos section of the Forno Bravo web site, and I think they look great. As you note, if you build your stand as describe, your support will be good under the hearth.

    If you are doing to put the oven directly on footings, not a slab, make sure that they are level and capable of carring the 1500-odd pound load. You wouldn't want it to settle and not be level.

    It seems as though firebricks are all a little different in size -- so it don't think we can be completely accurate with brick counts. Have any builders kept really good counts on their brick dimension and usage? The basic idea is to use a standard low-mid dut firebrick because it is findable and cost-effective, then do the cuts to build the dome.

    Pizza Ovens
    Outdoor Fireplaces


    • #3
      thanks, James

      Thank you for your reply, James. Yes, I was thinking to pour a round hearth also for the oven. And of course put these radial block footings on a proper round slab!

      Meanwhile I have received a reply from an Australian supplier about the odd "fractions" in the brick sizes - it turns out they actually provide you will fully cut, as a kit for the different sizes of dome ovens. Here's what I received from toniataylor at darleyrefractories dot com dot au (I cite the address in case there are other potential Aussie brick oven builders :-) )

      ================================================== ====
      Hi Luis,
      Yes, these bricks are cut to form the dome. So they are 230mm long x
      115mm wide x 75mm thick at one end that tapers down to either 57 or 63.
      These would be the best way to go by far - rather than have to hand cut
      each brick.
      The idea of firebricks is that there is as small a gap as possible
      between each brick (mortar joins between 1-3mm).

      I don't have any plans on how to make these ovens, the approximate
      requirements were worked out by our last Plant Manager(who was wonderful
      at this), but he has since retired.

      I can only tell you that we have quite a lot of people buy these bricks
      and make the dome oven - although if you haven't done much bricklaying,
      I believe that the dome can be quite difficult to build. You are
      building it from 4 sides instead of 2, and it needs to be precise as the
      last brick will key in the whole lot together.

      ================================================== ======

      Darley Refractories sell kits for 1 metre diameter ovens consisting of 67 of one type of cut brick, and 33 of the other (forget which is which). Also part of the kit are 25 pizza floor tiles, and assorted mortar, insulation, vermiculite etc.

      I am waiting to hear from them re freight prices to my location in the coastal woods of NSW.

      One thing I noticed is that theyur materials list does NOT provide for any first course of 'soldier' bricks as you have for the Pompeii oven - what I might do is fire up my old CAD program, Visio, and plug in the various types of bricks listed to build a virtual model of the thing with their numbers and measurements. Will then report back, respectively ask for more advice from the forum...

      La ringrazio per le sue righe,

      Ci vediamo :-)


      NB: For those Australian oven builders, I could supply the maker's "ingredients' list for the various sizes of pre-cut domes as a Word document.
      Last edited by carioca; 10-06-2006, 03:31 AM.
      "I started out with nothing, and I've still got most of it"


      • #4
        Ciao Carioca,

        Good find. I went to their site, and the wood-fired oven page doesn't seem to work for me. Does anyone else have this problem. I would be interested in seeing more about their kits.
        Pizza Ovens
        Outdoor Fireplaces


        • #5
          dysfunctional site :-)

          Yes James, the site doesn't work on several levels - I think they need to do some serious work on it.

          I only found out about their kits by e-mailing them direct, whereupon the person Tonia (e-mail supplied in my earlier post, with 'at' and spaces in it) sent me three Word documents, one of them the page that I'll attach to this post if I manage. That is where I learned about their "precut" dome oven kits, with further information in her subsequent reply to my queries re the angles (I quoted that part of her reply).

          She hasn't yet replied with a quote for the whole kit & kaboodle, railed to my nearest railroad town (60 km).


          Attached Files
          Last edited by carioca; 10-06-2006, 07:36 PM. Reason: i can't see the attachment I uploaded with it...
          "I started out with nothing, and I've still got most of it"


          • #6
            pls check out the attachment

            Hello James,

            I've now managed to attach the Word doc as a txt file. Please have a closer look at their "full cut" dome pizza oven materials.

            They don't seem to include a first course of straight bricks...

            Their 1 m dia dome would equate to 39in - I'd have preferred your 42in size, but their next one up is 1.2 metres, which is a bit too big and requires a lot more materials.


            LMH a.k.a. Carioca
            "I started out with nothing, and I've still got most of it"


            • #7
              kit prices for a 39in dome

              Hi James et al.,

              further to earlier, the suppliers have today sent me a quotation for the 'kit' plus transport charges & tax - a third of the total goes to transport!

              I attach the .pdf file for you guys to check out what's on offer "Down-Under" :-)

              Would be grateful for any comments re the actual components.

              Kind regards,


              STOP PRESS: can't send attachment as is too large for your system (385KB). Anyone interested pls supply e-mail address and I'll send privately...
              "I started out with nothing, and I've still got most of it"


              • #8
                here's the oven kit price quote as a txt file...

                Originally posted by james
                Ciao Carioca,

                Good find. I went to their site, and the wood-fired oven page doesn't seem to work for me. Does anyone else have this problem. I would be interested in seeing more about their kits.
                Hello James et al.,

                further to earlier: I've now uploaded the supplier's quotation for a fully pre-cut dome oven kit as a text file.

                Australian oven builders may be interested...


                Attached Files
                "I started out with nothing, and I've still got most of it"


                • #9
                  This all sounds interesting. If you go ahead, we will look forward to seeing how it all comes together and how much work is involved. If it all comes together, perhaps we could put together a kit like this in both the U.S. and UK. Alf had actually brought this topic up before you located your source down under.

                  I think you will be fine with the 100cm, 39.3" oven.

                  Also, see if you can order more insulation. The cost isn't that much more, and the oven will hold heat better.

                  Pizza Ovens
                  Outdoor Fireplaces


                  • #10
                    what about the soldier course?

                    Hello James,

                    thanks for the encouragement. Yes, there is also a spun/woven ceramic blanket available for $A120... I am now designing the footings and hearth slab (on a pile/beam foundation) and will take pictures and add text as I go. In the event of a successful construction, I intend to bundle these "instructions" in an article that I might place with a suitable magazine or two... perhaps I can recoup some of the cost :-)

                    One or two things still bug me:

                    1. the Darley Refractories kit has NO rpt NO straight bricks for what you guys have described as a first course of 'soldiers'. Do I need to order a quantity of straights from them, or will the arch bricks form up into a dome from the hearth layer - without ill effects for the baking process?

                    2. The Darley cut (tapered) bricks measure 230 mm x 115 mm and taper from the normal thickness of 75 mm down to 63 mm (for two thirds of the total brick quantity ordered), and taper to 57 mm for the other third of the quantity needed for a 1000 mm diameter oven. How are YOUR cut bricks laid - with the short dimension facing the inside of the oven, or with the long side of the brick facing inside?

                    Thanks again.

                    Ci vediamo!
                    "I started out with nothing, and I've still got most of it"


                    • #11
                      I cut my bricks to make sure they were tight side to side, but did not cut them for a taper top to bottom. If they are tapered in both dimensions you want the short dimension inside (even if only tapered in one dimension the short side goes in). Tapering side to side makes sure the whole ring is locked. Tapering top to bottom just means you do not need to think about the angle of the joint and further minimizes mortar reducing the chance of the joints failing.

                      I don't think soldiers are necessary - I would bet they have designed these bricks to make a complete 39" arch - do they specify the dome height? Soldiers would raise the entire height of the dome. I would probably stay with the plans of the kit they are selling. It would be possible to make the oven less stable if you raise the dome on soldiers (although not really likely). I have a low dome (42" wide and 18" high) brick oven and have no problems using it for pizza and bread.

                      I think you are fortunate to have a cut brick option - still get to do it yourself but have the comfort of an engineered brick dome with tight joints.


                      • #12
                        taper etc.

                        Hello Maver,

                        thanks for your comments. I'll have to ring the supplier tomorrow to see which way the taper goes - I'm sure they would have mentioned it if the bricks were tapered both ways...

                        Trouble is, they do NOT rpt NOT have any plans or instructions: the supervisor who developed this 'full cut dome' kit has since retired (and is living in the U.S., I'm told!), so you get a load of bricks and mortar and tiles, and you're on your own :-)

                        That's why I keep asking these dumb questions. You're probably right about leaving out the solder course - the kit deos NOT mention straight bricks, only arch bricks, most of them with the flatter taper, about a third with the deeper taper.

                        IF they taper along the 230 mm length (sorry, can't do imperial units offhand), that would mean the oven wall would be TWICE as thick as the 4.5in suggested elsewhere on your forum! That would produce too much thermal mass, I'd have thought... So I hope they taper across the 115 mm width, which would mean they will be laid in 4.5in wide courses. This also seems to account for the low number of actual bricks in the kit (63 of the flat taper, 33 of the steeper taper, plus some extras I've asked for). But perhaps I shall be told otherwise tomorrow by the supplier...

                        The quote I received also includes 2 sheets of Calsil for insulation under the 50 mm thick floor tiles, which are 230 x 230 mm each.

                        There is NO mention of how the opening would be set out - perhaps one just leaves out a certain number of blocks each course? Another question to my patient Darley interlocutor, Tonia Taylor...

                        I've been stuffing around with an old IntelliCAD program trying to creat virtual blocks of the dimensions listed, and then assembling them into a virtual dome - but tonight I've gone back to pen and paper :-)

                        Last edited by carioca; 10-11-2006, 02:35 AM. Reason: typos, sorry
                        "I started out with nothing, and I've still got most of it"


                        • #13

                          OK, I was lazy and did not give that full attention. These sound like they are essentially full sized fire bricks tapered on the shortest (vertical) dimension - I bet you are right that it is along the 115mm width they are tapered. I'm a little surprised that the more aggressive taper (to 57mm) constitutes the lesser of the bricks. When I built my 42" low dome oven I had the taper going from more aggressive to less, so I used more bricks with aggressive angle to them (angle created by wood shims rather than pretapered bricks), although I started with 1/2 brick soldiers. With the way yours are tapered a split brick would make a fine soldier, probably with the 75mm on the inside.

                          You could assemble your oven with full size bricks but the 230mm length split in half would give you a rounder oven. You could then taper the upper rings yourself into trapezoids (no need on the lower 4 rings) to maintain a narrow vertical joint between the bricks. You can see this starting at row 5 of my oven dome picture here:


                          You can see that I tapered every other brick initially (to minimize cuts) until they were too close together, then tapered every one.

                          I think the vertical tapering is convenient and can ensure you end up with the proper dome profile but that making tight vertical seams (side to side) creates dome strength - but I'm no engineer. That's just a feel thing based on observations during my dome construction.


                          • #14
                            taper reviewed...

                            Hello Maver,

                            Thanks for your feedback, I'll definitely study your oven.

                            Meanwhile I just talked to a person at Darley Refractories. She confirmed that there is NO rpt NO written material covering the 'kit' which apparently was put together by a retired supervisor.

                            BUT: the taper runs across rpt across the width of the brick, i.e. one side of 230 mm is 75 mm high, the opposite side is 63 mm!

                            AND: the people who buy this stack of materials for a 'full cut dome' oven cut the 230 mm long brick in half to construct the arch - except for the first course, that uses the whole (but tapered) brick.

                            She said 90 per cent of the people who buy refractory bricks from the company to build ovens build DOMES!

                            Bye for now (I've got another attempt to coax our 13-y-o electric oven back to life before my wife blows her stack! We've been eating supermarket 'bread' for three weeks now...),

                            "I started out with nothing, and I've still got most of it"


                            • #15
                              so the taper appears designed to help with creating tight seams in the vertical arch. I think it makes sense that the average oven maker would split the bricks in half. Making the cuts to form trapezoids is not much harder. I believe I used a 15 degree tilt to the skil saw. For the bricks near the top of the dome I tapered them both top to bottom and in to out.