Insulating slab with Super Isol

[dmun]

slip plane

Question for anyone....why did the plans change from utilizing the slip plane?

Not only was it decided it was not needed, but someone with experience in masonry pointed out that the aluminum would be corroded by the lime in the concrete.

[Pedro_2004]

I've just built my barrel shaped oven .....using the method advocated by Rado ... firstly we poured 4" vermiculite concrete as the insulation layer for the hearth then 4 " of concrete ....surely the reasoning behind putting the insulation layer below the concrete layer is that you want to increase the thermal mass of the oven ...you actually need the concrete slab to heat up to allow more heat to be stored in the oven and then radiated back for cooking ....sticking insulation above the concrete IMHO is not the correct way to go...also again IMHO it doesnt really matter if the aluminium slip plane does eventually corrode all you are trying to do is prevent the concrete slab chemically bonding to the support blocks whilst its going off....once its cured then it will be able to move at will

[dmun]

The reasoning behind putting the insulation layer below the concrete layer is that you want to increase the thermal mass of the oven ...you actually need the concrete slab to heat up to allow more heat to be stored in the oven and then radiated back for cooking .

If you want enough thermal mass to bake multiple batches of bread, and keep the oven hot from day to day for everyday use, then you want as much thermal mass as you can heat up.

Most of the folks around here are mad for 700 degree f. pizza baking, and use their ovens only on, say, weekends. It's brutally difficult, and time and wood consuming, to heat up a high thermal mass oven to that temperature. But if you are a regular baker, rather than a weekend pizzaolo, then the massive bread oven is the way to go.

[james]

Hi Pedro,

Welcome to the group. I'm sure you are going to enjoy your oven.

There are numerous postings on the forum that discuss the trade offs between the various oven design styles and hearth desigin philosophies. Take a look around -- it is interesting to read. For people just getting started, we strongly recommend the Italian oven design and hearth with the insulation on top. It is basically the oven and hearth design that you see in all of the pizzerias and backyard brick ovens in Italy. I have seen instructions for the insulation directly below the cooking floor in nice 3D drawings, simple line drawings, and hand sketched instructions from Italian builders and designers. There is a great deal of history and experience behind the design regarding heat up time, high heat retention, oven efficiency and pizza cooking.

I have to admit that I get a kick out of an Australian telling folks how to make a pizza oven. It's kind of like getting your NFL gear and rulebook from an Italian. Who knows what you'd get. There are scores of thousands of people involved in the pizza oven and pizzeria industry in Italy, with multiple trade shows, magazines and professional associations -- and I don't think that they are all wrong.

James

[Pedro_2004]

Thanks for the welcome James
I did actually use quite a bit of your site as a resource for building my oven so its kind of a hybrid design !
Most of the folks around here are mad for 700 degree f. pizza baking, and use their ovens only on, say, weekends. It's brutally difficult, and time and wood consuming, to heat up a high thermal mass oven to that temperature.
That I do agree with ! ..once there its great but it does take some doing
I do see your point so I defer to the Italians great experience in this ..