Floating Oven Floor?

[vincentvintris]

Hello:
does anybody have experience with the design shown in the picture attached? The foundation of the oven usually laying on top of the base walls is here "floating" between the walls and is tied into the walls with rebar.

I'm trying to find out if this is a good way to go.
The reasoning is that by "disconnecting" the floor from the walls of the base you create a thermal barrier. That in essence helps to reduce heat leaks from the oven itself.
I'm concerned about the stability of such a design. Is it worth it?
Thanks so much
Vincent

[maver]

Vincent, it's a neat concept, but with the pompeii style oven you're already in trouble if the heat makes it through your underoven insulation into the concrete layer. I could imagine with a high thermal mass bread oven that having a thermal break between the concrete table and the sides of the stand might have value. Usually that design includes insulation under the concrete pad. So if your intent is pizza or even a home bread oven that you plan only one or two batches of bread, it's not likely worthwhile. Your insulating layer under the hearth firebricks does far more to stop heat loss. The bigger decision is perlite or vermiculite concrete vs a product like superisol.

Marc

[james]

I have experience with it, and have done it twice. It's quite unusual, and it requires a lot more work that the hearth design in with the Pompeii Oven. That hearth has the concrete layer on top and the vermiculite underneath, which you do not want in a pizza oven (either commercial or residential).

So the good news is that you don't have to do it. The hearth described on the Pompeii plans works great, and is a lot easier to build.

James

[dmun]

Wow, that's not a good idea. Rebar seems strong, but mostly in tension. Putting huge lateral forces on it doesn't seem like a good idea. Also, what if something goes wrong? An accidental fire in the wood storage area could turn the only support for the oven into licorice.

In concrete work, rebar is buried in the concrete fully, to prevent moisture, rust, swelling, and concrete failure. Having the rebar stick out violates that concept as well.

Maver has it right: with modern insulation, there's no reason for the support slab to get hot at all.

[vincentvintris]

Great! Thanks for the quick replies. I had a feeling you would say what you said.

As we are planning to bake Pizza, pan fry meats , but bake breads sometimes also I have my eye on the barrel design attached.

It also seems to reduce the brick cutting if compared to the dome design.

Would that be a good choice?
Thanks
Vincent

[dmun]

If pizza is at the top of the list, don't choose the barrel vault. They take more time and wood to heat up, and are hard to keep at pizza temperatures.

why italian wood fired ovens round (Why Italian Wood-Fired Ovens are Round)

The round oven looks harder to build, but people who've built both report they're about the same.

[CanuckJim]

Vincent,

Mine is an Alan Scott design barrel vault oven with a floating slab, a 4' x 3' cooking floor and very high mass. However, it was built specifically for bread in commercial quantities. I can't agree that the "exposed" rebar is subject to rust, because it's covered with 4" block to form the enclosure walls. For my purposes the thermal break is a good feature, but for yours I think not. If I was building an oven strictly for home use, I'd go with the Pompeii design and use as much ceramic insulation as I could afford. It's much, much easier to build, although with it you do get involved in more cutting than with a barrel vault design. Have a look at the finished oven pics in the gallery for my oven. Stick with the Pompeii; you'll be glad you did.

Jim