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Barrel vault with pompeii wall cross section?

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  • Barrel vault with pompeii wall cross section?

    I'm pretty sure i know the direction this thread is going to go but i'm going to ask my question anyway.

    I found this design from Family Handyman and got really excited to build a pizza oven next summer. I'll spend the winter researching what i need to materials and where to find them here in Sweden.

    Now everyone on here seems to be very pro dome/pompeii style oven and anti barrel vault. However just eyeballing the plans it seems like the barrel vault will be a much simpler construction than a dome (i have never done any masonry but can be quite adept once i've researched how to do things) as well as using less fire bricks. I'm going to attempt to keep cost down where I can.

    Most of what i find on barrel vaults here refers to the Allen Scott oven. However the Scott ovens seem to have extremely thick walls and therefore very high thermal mass. I haven't seen many reviews/examples of a barrel vault with thinner walls.
    So my question is could i build the family handyman barrel vault with a few adjustments that put it more in line with the pompeii dome build and would it perform similarly? Mainly I would put a better insulating layer in between the fire bricks and the concrete pad, as welll as a thermal blanket in between the fire bricks and the outer layer of bricks. Would this work or should i just follow a dome build (which i'm assuming what most of the comments are going to be)

    Mostly I'm looking for an oven to make both pizza and bread. Ideally for use at least once a month but not constantly. I bake a lot of bread, meaning i bake bread often but not massive quantities all at once. So i definitily want something that can do well with both types of baking. Now i'm not debating that the dome is the 'best' form/shape for pizza cooking, i'm simply trying to stay within my abilities while still acheiving the functionality i'm looking for.

    Thanks for your feedback

  • #2
    FYI, Typically hyperlinks to other commercial sites not allowed but this link is right on the border of a DIYer site so the link is tentatively approved. That said, I perused the barrel build and there are quite a number of design flaws that you want to review, ie no insulation on dome and floor, As you noted, most of the ovens on this site are pompeii but there are a few barrels. I suggest you download the cheap or free plans form the Forno Bravo store site and read it carefully, it is a great resource for design and construction. Also, under the blog's Newbie section and the sticky called Treasure Archives, there are links to many well documented, dome, cast, and some barrels.

    PS, dome builds are not any harder than barrels and in some ways easier. Many builders of domes on this site have never laid a brick before and survived the task, me being one. You can also look at a cast oven.
    Last edited by UtahBeehiver; 09-01-2023, 12:29 PM.
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    • #3
      I think it's doubtful this oven would reach pizza temperatures because of the lack of insulation and the the high thermal mass of the vault.
      For ovens the relationship between the strength of the structure and thickness of the walls is an important one. The strength is increased the thicker the walls are built. But at the same time the thermal expansion challenges the structural integrity. So the thinner the wall thickness the more susceptible they become from the both the forms structure and thermal expansion. Usually a happy compromise is found somewhere in the middle. Unfortunately the barrel vault is a far less structurally stable form than a hemisphere and usually requires either steel bracing or buttressing of the walls. The oven shown in the video relies on strength increase from the second layer of bricks. Unfortunately this has drawbacks by massively increasing the the wall thickness thereby also massively increasing thermal mass. The amount of energy required to heat the structure therefore is also massively increased as is the time required to get the structure sufficiently hot. Another detail that is not shown in the video is the detail of the end walls. An expanding barrel vault has a tendency to push out the end walls, which compromises the mortar joints between the vault and the end walls. For this reason they are better constructed under the vault rather than beside it. The oven as shown has an open front so heat loss there will be very high, further increasing fuel consumption and heat up times. The updraft flue arrangement also contributes to high heat loss and excessive fuel consumption.

      Just as the Inuit found after thousands of years of trial and error, the best solution for an unsupported, unreinforced structure is a catenary dome igloo, so too has the hemisphere proved to be the preferred solution for an “all-round” oven.

      Unfortunately the internet abounds with easy DIY builds from folk who have little knowledge or experience with oven design or use.

      By all means build according to this design, but if you do, please report back so others can be warned not to follow the same path of disappointment.
      Last edited by david s; 09-01-2023, 03:53 PM.
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