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My Modified Barrel Vault in Texas

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  • #61
    Re: My Modified Barrel Vault in Texas

    If I am constructing a similar opening wall, would there be any downside to putting a simple steel bar across the opening to support that central area? My biggest concern is the differential expansion and contraction of metal in a heated brick joint; does anyone have any experience with making this secure, or will it all just eventually crack and need to be re-cemented (if possible) over time?

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    • #62
      Re: My Modified Barrel Vault in Texas

      Originally posted by luca View Post
      If I am constructing a similar opening wall, would there be any downside to putting a simple steel bar across the opening to support that central area? My biggest concern is the differential expansion and contraction of metal in a heated brick joint; does anyone have any experience with making this secure, or will it all just eventually crack and need to be re-cemented (if possible) over time?
      Or, do a Welsh arch like this one over a vent.

      The English language was invented by people who couldnt spell.

      My Build.

      Books.

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      • #63
        Re: My Modified Barrel Vault in Texas

        It's a good idea, but won't work here since the adjoining bricks are also poorly supported, and the expanse is over the 9 inch length of a regular brick (see the above picture again). This leads me back to the steel lintel as the only practical support structure. Any other ideas out there? By the way, you can see my build progress at:
        Pictures by Conteparker - Photobucket

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        • #64
          Re: My Modified Barrel Vault in Texas

          Just looked at your pics, looks doable to me?
          The English language was invented by people who couldnt spell.

          My Build.

          Books.

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          • #65
            Re: My Modified Barrel Vault in Texas

            What about casting a lintel out of Castable refractory? I used angle iron in my first oven to form a square opening, and although the angle was in good shape upon demolition the bricks and mortar around it certainly showed signs of damage from thermal expansion. Nothing horrible, but some large pieces of mortar had cracked and broken off and a few bricks were ever so slightly loose. For my new oven I cast the entire entry area out of KS-4V plus and although the oven isn't yet complete it was a nice material to work with and I feel the result will be much sturdier.

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            • #66
              Re: My Modified Barrel Vault in Texas

              I appreciate the input about your first oven and the angle iron; that's what I'm concerned about. As for the "castable refractory," is that the same as the fireclay and mortar mix, or is it completely different? (I'm in Vermont, so my options for supplies are pretty limited.) Regarding Brickie's comment that the Welsh arch still looks doable--which is by far the easiest option--do you think the limited brick surface area under each end of the Welsh arch in this situation is enough to support that arch (I suppose I could dry fit it and see if it collapses on me without the mortar in place; good idea?)

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              • #67
                Re: My Modified Barrel Vault in Texas

                As for the "castable refractory," is that the same as the fireclay and mortar mix, or is it completely different?
                Completely different. The homebrew mortar mix you mention is just that: mortar to put bricks together. Castable refractory concrete is one of hundreds of commercial mixes used in various kiln and furnace application. They come from refractory dealers, not brickyards.
                My geodesic oven project: part 1, part 2

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                • #68
                  Re: My Modified Barrel Vault in Texas

                  Alan Scott ( one of the authors of the Bread Builders and masonry ovens) uses angle iron in all of his barrel vault ovens at the mouth of the oven. Can't imagine it would be a problem after all of his builds.

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                  • #69
                    Re: My Modified Barrel Vault in Texas

                    The fornobravo plans used to use it to. I think there is a reason it "used to". I had no concerns using it when I built because I had seen it done before, but it was certainly an issue, and you would have never known it was so bad if you didn't demo the oven and see the other side. From the interior it looked ok.

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                    • #70
                      Re: My Modified Barrel Vault in Texas

                      The thermal expansion of steel and concrete are virtually identical so I guess that would also go for brickwork. The trouble is the steel is in a place where it's going to get hot first and being a much better conductor, will expand before the brickwork has time to heat up. Many builders have used steel lintels and not reported problems, but if you are concerned then maybe leave a little space either end of the angle iron so it has room to move without placing stress on the brickwork.
                      Kindled with zeal and fired with passion.

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                      • #71
                        Re: My Modified Barrel Vault in Texas

                        Yep my ovens opening is square with double pieces of angle as a lintle...
                        do I have cracks yes..... is it a problem....no
                        There small and well everyone reports cracks of some type.... mine well they disappear over the work week and reappear when the oven hot on the weekends....

                        regards Dave
                        Measure twice
                        Cut once
                        Fit in position with largest hammer

                        My Build
                        http://www.fornobravo.com/forum/f51/...ild-14444.html
                        My Door
                        http://www.fornobravo.com/forum/f28/...ock-17190.html

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                        • #72
                          Re: My Modified Barrel Vault in Texas

                          I decided to take Brickie's suggestion and make a "Welsh Arch" to support the opening. It dry fitted well and so I cemented it all last week and all looks good. Thanks for all of the input!
                          Last edited by luca; 08-26-2011, 06:06 AM.

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                          • #73
                            Re: My Modified Barrel Vault in Texas

                            If anyone is still monitoring this page, I am now at the stage of enclosing and insulating the enclosure with either perlite or vermiculite. Since I'm in a very cold climate (Vermont) I'm concerned about water retention around the oven in winter--even with a roof and "box"-- and have read that Perlite retains less water than Vermiculite. Anyone have any experience with Perlite as an insulator and/or any issues with using it, as opposed to Vermiculite?

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                            • #74
                              Re: My Modified Barrel Vault in Texas

                              It is an excellent insulator and most of it available to the public is siliconized which helps with the water issue.

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