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Enclosure insulation - Forno Bravo Forum: The Wood-Fired Oven Community


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Enclosure insulation

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  • Enclosure insulation

    Just a quick question here. I guess you could say I'm trying to shoe-horn as large an oven as I can into my space so dimensions can be critical.
    I plan on a metal stud framed enclosure and was wondering what clearance I could get away with. See my sketch attached below. can I include the depth of my metal stud in the 4 inch minimum insulation. I'll have a ceramic blanket in place the about an inch to the stud layed flay on the hearth, as a sill you could say, then my vertical studs are placed inside it. since they are metal I was wondering how little clearance I could get way with.
    Did I explain well enough?
    Anyway take a look at the sketch.

    Thanks, Bob

  • #2
    Re: Enclosure insulation

    My suggestion: don't use half bricks. Use 3" slices (third bricks) and/or 3" chopped-down bricks for standing soldiers if you're going to do that. Then cram as much insulation around it as you can. That's assuming that you prioritize floor space highly. I fit a 34" oven onto a 48"x54" stand with 4" of high-efficiency insulation, so there's my bias for you. If you make the floor smaller then you can use half bricks. If you make the floor smaller and use 3" bricks you can use more insulation, which might be best of all :-)

    Are you primarily interested in quick heat-up times for pizza making and good insulation for retained heat purposes, or are you interested in more thermal mass for baking bread, retaining days' worth of heat, etc? Because that would inform your decision. 4.5" half bricks plus 0.5" of Heat Stop would yield a wall thickness of 5" -- a total of 10" of masonry enclosing your dome floor. Personally I don't see any reason to do that if you're pressed for space. You could get back 1.5" of additional clearance on each side by using thinner walls. Then you could use a 2" blanket and still have a full inch of clearance. If you place the studs strategically, you might be able to cram even more insulation in. Or you could dump vermiculite into the voids. Whatever. (I cheated and used expansion bolts in some places) Metal studs and cement board are not supposed to become structurally unsound at the ~150 degree temps that you might expect at the edge of a 2" ceramic blanket, but YMMV.

    ps. If you go down to 3", use a catenary curve and/or a rebar buttress for your dome.
    Last edited by ttriche; 06-17-2009, 09:15 AM.


    • #3
      Re: Enclosure insulation

      Can I include the depth of my metal stud in the 4 inch minimum insulation?
      Yes. Remember, your oven slopes in from the base. You don't need to do the full metal stud where it intersects with the curve, you can place a horizontal a foot or so up, and do your studs up from there, at the sides and back. In other words, your four inches of insulation can come right up to the cement board if you place your framing carefully.
      My geodesic oven project: part 1, part 2


      • #4
        Re: Enclosure insulation

        Thanks I was hoping the spacing of studs vs the curve of the dome would gain me some space, also not shown in my sketch, I thought I'd have the sill or horizontal stud laying on the structural concrete slab recessed below the surface of the vermiculite slab. Like a step.


        • #5
          Re: Enclosure insulation

          I cut it really close on mine and framed a sort of "window" with the studs right next to the curve to get some extra clearance.
          Here are some photos in my thread:
          It never gets hot on the outside.

          My Oven Thread:


          • #6
            Re: Enclosure insulation

            A picture is worth a thousand words, thank you. I read your oven build pages. Great info there for me. You cut it much closer than I was planning. It was good hear you didn't have a heat problem. I'll probably follow suite.

            Thanks again, Bob