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purkaer 01-10-2012 08:24 AM

Second raised floor inside
Hi all

Been reading a lot in here.

Want to build a oven on a trailer, and thinking about a steel oven dome and a 1 inch firebrick bottom, and then the wierd thing im thinking about is to have a raised floor(of soapstone) or mayby to inside the oven. The thought is that having heat/fire under and around the cooking floor Will give more heat and faster firing up times and give the possibilty of constant cooking without refiring.

The idea is from "american fladbreads oven" in the book "the bread builders"

What dó you Think?

My thought is that i dont very much thermalmass and still can cook a lot of pizzas and have a light weight oven for a trailer.

Regards, thomas

texassourdough 01-10-2012 11:41 AM

Re: Second raised floor inside
You need to research white ovens. White ovens are used for bread but to my knowledge not for pizza. IF you only have the fire under the hearth the hearth will be too hot relative to the dome and your base will burn while the top will be pale. Not what people expect from a WFO. There may (and probably are) workarounds to help the problem will probably be on your own.

purkaer 01-11-2012 02:24 AM

Re: Second raised floor inside
Mayby I wasn't clear enought. I still Want fire over the top, the idea is building a lighter oven with very little thermalmass and then in the middle of the oven have a square steelframe Holding a soapstone mayby 4-6 inch above the normal floor, and the get the Best from both the white and black ovens.


david s 01-11-2012 08:25 PM

Re: Second raised floor inside
I tried a similar approach with my first oven. Having a raised floor section in the middle for cooking in the hope that it would be easier to clear the ash off the raised section and the lower part around the perimeter would contain the ash and coals. It kind of worked, but I ended up making it all flat in the end. It is easy to clear the floor of ash with a blow pipe and having an uneven floor is a pain to clean, so my preference is now a flat floor, but try it out you may prefer it.

texassourdough 01-12-2012 06:59 AM

Re: Second raised floor inside
You don't particularly need mass for a pizza oven. You are NOT relying much on stored heat to cook the pizza. You need some mass in the base because when you plop the pie on the hearth it will drop the hearth temp surface temp dramatically - probably to the 200 F range or below. The only way for the hearth to "cook" the bottom of the pie is for heat to come from the refractory in the hearth. So the hearth needs some mass. If you make it too light you will be forever having to scrape coals back over the hearth to recharge and then having to reclean it. Not good for productivity!

You are relying on flames and radiant heat (a function of dome surface temp (which makes insulation important but that is light) and not stored heat) to cook the top of the pizza. So I would suggest making a relatively normal hearth, a light/thin dome (as best you can) with lots of insulation (actually everywhere hearth and dome).

I would think, as David alludes, cleaning under an elevated stone would be a pain. And you would have to to keep the fire going properly.

Good Luck1

purkaer 01-12-2012 07:24 AM

Re: Second raised floor inside
Thanks for the input to all of you!

What thickness of bottom bricks? 2-2,5" ?
And would a steel dome of 1/3" be enought dome mass? Mayby If the internal height is low?


texassourdough 01-12-2012 09:30 AM

Re: Second raised floor inside
I am not a construction expert but I do have a good grasp of heat content and heat flow...

I would think - building from the bottom - probably a steel pan/sheet to hold the oven, insulation - probably two layers of good sheet as for a regular oven, two layers of fire bricks with the top being the hearth. I would use thicker ones.

The dome is IMO almost immaterial except for the fact that it must be durable to survive being bounced around on a trailer and heated and cooled across a broad range. For a refractory dome that probably means an inch and a half or so of refractory cement. Steel could probably be a quarter of an inch. Would probably eventually rust out and have to be replaced. Part of the good news of this approach is you could proably just set a steel dome over the hearth and - if you had problems simply disassemble it and try again.

The dome should, however be well insulated or it won't get hot enough and would be dangerous to the public.

I reiterate...there is no particular reason I can think of that you need dome mass for pizza. (I can conjure some up but they aren't IMO really valid!)

Good luck!

purkaer 01-13-2012 07:19 AM

Re: Second raised floor inside
Thanks Jay!

I must try experimenting with the dome.
I many threads they say a floor thickness of 2.5" firebricks, but you talk about two layers of firebricks? Wont that be to much thermalmass for hearth?


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