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Canada 150 Pompeii Build - a few questions

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  • Canada 150 Pompeii Build - a few questions

    Hello all - like many others, I have been lurking for some time thinking of my WFO build and I'm excited to get started. Given that it's Canada's 150th Birthday this year, I thought it was a fine way to celebrate a birthday. I've started my Pompeii oven build in Grey County Ontario, Canada and hope to finish later this summer. I have a rough cardboard template and have done some sizing analysis with Sketchup.

    So far I have poured the 12' x 10' slab (will be covered with some food prep / seating) - I did the excavation and framed and added rebar but had a professional crew and truck do the pour as part of a larger barn build (best $400 I've ever spent to save my back!). We placed a 69" x 61" block stand a few weeks ago. I had originally planned a 42" corner build but have modified this down to 36" or 39" based on the size of the stand I wanted on the slab. I spent last weekend building the frames for the hearth, which I plan to pour this weekend.

    The high-level details are as follows:
    • 4" reinforced concrete hearth
    • 36 or 39" ID floor with dome bricks outside the floor
    • Door 18" W x 11" T
    • Plan for 4" of FB insulation under floor and drain holes drilled under insulation (may add something under FB to prevent any moisture wicking)
    • 3" insulating blanket and 1" stucco exterior
    • Plan to cut bricks with bevel only (not bevel and taper)
    • Will add thermal break between oven and landing
    • 6" flue
    • Integrated arch design (saying this and have looked at it but not fully processed!)
    As I finalize my plans and get started with the hearth, I have a few questions that I hope others could help with:
    1. I filled every second core of the block stand w rebar/concrete. The cores above the lintel are empty. Should I just cover them for the hearth pour or should they be filled as well? If so, how do you block the bottom of the cores?
    2. Per the plans, are empty concrete bags stuffed in the core sufficient to prevent the cores from filling?
    3. I'm still confused by the "Vent Landing" and "Oven Landing" sizes. I was thinking of the vent landing (inner arch, vent and outer arch - correct?) being about 12 - 13" total length for a 6" flue. So the total length excluding the oven landing is: 36" floor + 4.5" rear brick + 3" rear insulation + 1" stucco + 13" vent landing for total length? I had originally thought of a 12" oven landing as well to stage food in front of oven, but I'm thinking that may be too long of a reach? Thoughts?
    4. Any other tips before I do the hearth pour? Concrete and mixer are ordered and will be delivered this Friday.

    Thanks C150

  • #2


    • #3
      How is the lintel held? Iron angles?
      1. While I don't like lintels and went with the arch instead , if I had to have one I would fill it while pouring the slab. I would block the bottom by providing a plywood (or any other flat surface) propped underneath it
      3. Perhaps attach your drawing? :-)
      4. Probably to late but getting a pre owned mixer would have saved some funds.
      Also my concrete mixer was useless for mixing mortar,material just stuck to sides, had to add way to much water, perhaps it's my lack of experience. but now I mix mortar by hand in a tub. Not that hard and I get excellent consistency

      Good luck
      Post pictures!

      My 36" -


      • #4
        Couple comments:
        6" in flue may be on small side for a 39" oven.
        I am happy with my choice of FoamGlas on the bottom layer of hearth insulation as it is unaffected by moisture. I found it easy to cut, and the same price as CaSil. Highly recommend it. See Utahbeehiver's build.

        Your entry width seems small as well. That is the size of mine, on a 32" oven. There is controversy on this subject trading off ease if access vs heat loss.

        Your depth calculation is off as the inner arch will be well within the diameter of the dome. Assuming your calc above was for a 36".


        • #5
          Thanks all for the guidance. I'll look into the Foamglas option. Do you have Foamglas on bottom and then CalSil on top? I need to spend some more time thinking and drawing the vent landing to figure out actual size. Thanks for the tips.

          We managed to get the hearth poured this weekend. Managed to push hard and get everything in place and covered before waves of torrential rain rain (and a tornado warning :-/) hit us. I'm glad to have the slab, stand and hearth behind me! The hearth is structurally fine, but I probably should have left it alone after floating. When I tried to edge, I seemed to expose more aggregate. I keep telling myself that it will largely be covered by an oven and the siding on the stand! I may end up polishing some of the exposed concrete. Importantly, we did set a drink holder in the slab!

          After finalizing all the framing, leveling, etc I backed a trailer up to the side of the stand and had the 3 cu' mixer on a stand in the trailer. That allowed us to direct pour into the hearth and save everyone's backs. We had the pallet of concrete off to the side on a set of forks. I also built a quick concrete chute from plywood and 2x6's to help with the placement at the end of the form. We generally only mixed ~3 bags at a time but managed to get everything in place without too much problem. When we tried more bags it seemed like we had to stop more often to scrape the dry mix inside the mixer.

          I thankfully had ordered a number of extra bags of concrete - suggest everyone do this as well - as I managed to tear a number of bags open while carelessly moving the pallet with my forks. We ended up only having two spare bags, which isn't a large margin of error.

          Based on my build log, I think I'm about 40 hours into the build with an additional 50 man hours of 'friends and family' to excavate and pour slab, build the block stand and pour the hearth (and that's with the slab pour contracted out!). Slow progress! I also figure I'm about C$1,000 into the build cost as well 'all in'. I'm hoping I can average down the cost per pizza!



          • #6
            Foamglas on bottom as it won't absorb moisture. Gets the calsil off of the hearth.
            Last edited by cnegrelli; 06-19-2017, 02:13 PM.


            • #7
              OK, I will likely convert this to a build thread, but I have a few questions. Plan is to lay the insulation and floor down this weekend. Attached are a 1/10 scale view of the oven and vent landing as well as a 1/5th scale of the floor and design. I have a bit of wiggle room on the total vent area (inner arch, vent landing and outer arch) but still have a few questions:
              1. My plan is to have the oven floor inside the dome with the dome build on 4" of base insulation. I think this will be the case for the arches and vent as well (ie those floor bricks will be inside the arches, vent area, etc. In my attached design the arches vent etc would be build around the floor shown in the plans (which is 18" wide). Does that make sense?
              2. I'm still trying to get my head around the inner arch. In my plan, I've assumed the arch is 4.5" deep 'at the bottom' where it matches the oven floor. I realize that the actual brick will be longer (up to 9") to allow the arch to integrate into the dome. Does the total depth of ~16" make sense for a 36" oven? I still have to figure out how to draw the inner arch integration with the dome to scale - any tips?!
              3. Finally, I have attached a version of the floor layout. My biggest question is how do I cut the bricks with a rounded profile on vertical saw blade? I'm a bit worried about the small slivers that need to be cut - I don't want my fingers that close to the blade.
              4. My plan is to have a center brick (the golden brick) that I will remove and insert a block of wood with the IT attached to get the right level for the pivot point. Does that approach make sense? I see that I may need to shift the pattern to eliminate the small pieces at the opening of the vent area.
              Thanks for any feedback and advice.


              Click image for larger version

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              Click image for larger version

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              • #8
                Great start on planning and thought process.

                Couple comments - Dome or enclosure, if enclosure oven is getting close to edge on right side
                You will not need 40 floor bricks, partial from other areas can be used, ie 20 and 36, 24 and 40 etc.
                Inner arch should intersect the radius of the dome for proper placement of the arch assembly, especially if you do a tapered inner arch. The longest brick will be the top dead center of the inner arch. Cutting floor, you just to small cord cuts and use the side of the wet saw blade to feather the edge. If you are doing an enclosed oven, then place the dome on the floor bricks and rough cut the shape. You can even do this with an igloo as well, you just don't have to be a precise and cutting to fit inside. Just make sure all floor bricks and dome edge have insulation under them. Check out the Treasure Archives in the Newbie Section for some of the more documented builds. I would suggest you start you own thread so not to hijack this thread.
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