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boski1 04-29-2005 11:45 AM

Oven Floor Selection
Greetings to all,

I'm a newbie wishing to build the Pompeii style oven with as few disasters as possible along the way. I think I get the concept of overkill on thermal mass but still a bit unsettled on the best cooking floor to use, so please educate me.

Would a solid floor poured with commercial refractory cement be a justified benefit as opposed to firebrick? If the solid floor is justified then should it be spaced away from the dome wall, and how much space?

Also wondering if floor size dictates the dome height to be used. Many thanks for providing the plans posted on your site.


ColonelCorn76 05-03-2005 06:41 PM

Theoretically the solid refractory floor is optimum from a surface standpoint (smooth). You'd pour it to be the outside diameter of the oven (e.g. 53" for a 42" inside diameter oven) and then place the side bricks on top.

Being a non-professional though, I find that finding the refractory & getting the floor smooth & crack free is difficult enough that the brick method is best. Small differences between bricks don't hurt any and using a basketweave pattern eliminates the peel hanging up on a line of bricks. The brick method also allows for the replacement of an individual brick that might crack or break (most probably due to hitting it with something as thermal stresses are not sufficient to break them under normal backyard use).


ColonelCorn76 05-03-2005 06:48 PM

floor size/dome height
Oops. Forgot this one. The floor size definitely has an effect on the dome height. There's a "golden triangle" of measurements in play with a chimneyless brick oven (where the chimney is outside the cooking/burning space). These are diameter/2 = dome height (internal dimensions) and dome height x 65% for the door opening height.

In practice there's some fudge room here and the oven will still work fine. This dome heights is a good balance between a bread & pizza oven. Pizza only ovens are squatter (30-40% of the diameter measurements). The door height can (and has) ranged from 55% to 70%. The ends of these ratios are fussy though and the sweet spot tends to be in the 62-67% range with more tolerance on the bottom side of the range (e.g. a 60% ratio is better than a 70% one).


david 05-04-2005 05:37 AM

Hi Jim,
Do you know of any specific ratio measurements for optimum performance regarding the vent/flue sizing to the oven?

boski1 05-04-2005 05:54 AM

Thanks Jim. Have you ever actually built one of these round ovens? If so, any further advice or warnings I should heed?

ColonelCorn76 05-05-2005 08:14 PM


Originally Posted by david
Hi Jim,
Do you know of any specific ratio measurements for optimum performance regarding the vent/flue sizing to the oven?

This one is harder than the question about the dome height/diameter/door size question. Flue sizing is dependent on local conditions like prevailing wind, height of chimney, proximity of higher structures nearby, etc. But a good rule of thumb is a flue that has an area of about 3-4 times the door height.


ColonelCorn76 05-05-2005 08:21 PM


Originally Posted by boski1
Thanks Jim. Have you ever actually built one of these round ovens? If so, any further advice or warnings I should heed?

Ummm...yes. In fact, I did the engineering & design work on the Pompeii oven. Mine was the first one constructed. The construction photos, etc. you see on FornoBravo's website are mine (you can see more at I've also built a standard 32x36" Alan Scott design. The Pompeii came out of that experience and was specifically designed to address my issues with Alan's design.

As a backyard cook, I wanted an oven that could cook at least 1 load of bread on a firing, that would fire up to cooking heat in less time then it took to prepare the pizza dough (an hour or less), and can cook 3 or more pizzas at once. The last thing that James added as a requirement was that it be built using common materials & tools. That meant I used materials I could find locally at Home Depot/Lowes or my local lumber/masonry yard. As an engineer I'm not satisfied with leaving well enough alone which is why I've continued to refine the design of things like the hearth.

Alan's design is good for commercial bakery use where the oven is heated and then maintained at heat throughout multiple cooking cycles over the course of a week. The Pompeii is designed for real world backyard cooking.


david 05-05-2005 08:33 PM

Thanks Jim,
I am still pondering the vent/flue design issues.I've seen some angled Terra Cotta flue pipe that I could cut down for the vent and join to a 8x12 straight chimmney section.I think it would work ,but it seems very heavy? I was in Lowes today and they had a 36" double wall Stailess steel 8" dia pipe on sale for about $40 which seemed attractive also,if it would work?

ColonelCorn76 05-06-2005 05:45 PM

Terra Cotta flue is what I used. It is heavy but I built my vent (looks like a range hood) out of steel I welded into shape. It rests on the landing wall bricks and easily supports the weight of the flue section.

That being said, the stainless steel flue should work okay provided you make sure there's a nice wide vent leading to it (like in the neighborhood of 16 to 18" wide at the oven door) and you might need a second section to get enough height depending on what's around it. Try the single section first and if that's not enough you can toss another on top to extend it --- also, caps can be used to extend the height a bit too and will keep rain from pouring in there.

Careful with anything that's not straight. Angles & deviations require far more unrestricted area to flow & draft well. Alf is always good for a few tidbits of wisdom where that kind of design is involved.


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