First oven design recommendations for half barrel style

[mbzeitz]

Putting together a project plan for my first brick oven. This will be primarily for pizza, but will also be used for bread and other foods. I would like to build a half barrel style oven instead of a dome if I can build a half barrel that still turns out good pizza.

I was planning on using firebrick pre cut at an angle to make the top of the barrel, so the brick wall and barrel thickness would be 4.5". I have up to 48"x48" to work with, but that would be a very big oven to start with, maybe interior size of 36"x36"?

I am looking for recommendations on sizing for the oven, especially to be decent with pizza, despite being barrel style. This includes how tall to make the wall before the arch begins to curve in, what radius for the arch, what size actual cooking area, and whether to make the arch constant curvature, or flatter at the top?

Thanks!

[UtahBeehiver]

Tscar made a very nice barrel oven, here is a link to his build.

https://community.fornobravo.com/forum/good-background-information/brick-oven-photos/8871-it-is-begun

[SableSprings]

Welcome to the forum MBZeitz! Is there any reason you want to do the half barrel instead of a dome? I actually built a dome but then put on a facade to make it look like the half barrel. The Pompeii is still the best option when you want lots of variety in your cooking future ( IMHO ). With the barrel vault you will need to plan buttressing for the outward thrust of the arch ceiling. On the ovens here, the recommendation is at least 3"-4" of insulation over the outer structure and 2"-4" of ceramic board beneath the cooking floor. In addition, you'll be looking at outside render/finish).Those oven layers mean that your barrel vault oven floor would be a max (48-(3+3+4.5+4.5+0.5+0.5))=approximately 32" wide and deep. (We have members with very successful 21" ID domes, so the 32" oven is not too small.) My opinion is that trying to keep the fire and cooking floor working for pizza really favors the dome style. With the barrel vault you get restricted as to the actual space you are working. With a 32" ID dome you have a lot better temp control (and access)...again IMHO.

There's a pretty good thread on the advantages of both the dome and vault that would be worth your time reading. Here's the link

https://community.fornobravo.com/forum/good-background-information/newbie-forum/68-why-italian-wood-fired-ovens-are-round

That said, there are quite a few barrel vault builds documented in the forum...of course they work, but there is a reason that the dome style is more popular. Your arch in a barrel vault can be straight up for a good percentage with a shallow ceiling or half-circle starting at the floor. This is why and where the buttressing is important. Straighter sides mean more outward thrust and more required buttressing than the half circle approach.

[mbzeitz]

SableSprings,

Thank you for your reply. The main reason I want to build a barrel vault over a dome is reduction in cutting bricks and careful shaping to create the structure. With the barrel vault I can use trapezoidal precut bricks that will naturally make an arch. Making the dome will require cutting every brick and building a more complex inner form to support the structure as it is built. Since this is really a project for my sister in law who is still in high school, with me just helping I want to keep the brick cutting to a minimum. But if the only way to get a good pizza oven is to make a dome, I will strongly consider that, including the option of casting high density refractory cement (although that has the risk of casting defects ruining the whole build).

[UtahBeehiver]

There have been some decent brick ovens done with only a brick chisel and a grinder. In addition, there has been a surge in cast oven lately so this is certainly a good option as well. David S is our casting expert here on the forum (peruse his threads). Each style, dome,barrel, cast has it's own pros and cons with dome shape being the majority of the ovens whether brick or cast.

[david s]

Because of the thermal expansion of the bricks on firing and contraction on cooling. the structural integrity of the chosen form is tested. While the semi circular arch in architecture has proved itself as the Ancient Romans used extensively, it still requires buttressing. The collapse of arches that are no longer buttressed by adjoining arches in the Colleseum (see link), is a good example. Another solution is to use some steel bracing and if you research half barrel ovens on this site you will find examples of this. The reason the hemisphere became so popular is that it is self supporting and requires neither buttressing or bracing. A couple of thousand years has proved it’s suitability. You also need to be aware that the expanding half barrel vault has a tendency to push the end walls out so they should be built under rather than beside the vault for this reason. This is standard practice for kilns of this configuration and while they go more than double a WFO in temperature and corresponding thermal expansion, the same principle applies.

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