Double level pizza oven need help please

[geraldevans]

Hello as you will see in the photo I am in the first stages of building the pizza oven there will be two levels in this oven and my plan is about halfway up to putting a refractory brick so that I can have a bottom and top level for cooking. My question is this because my design is a little different I am wanting to reinforce the whole structure and I know the normal procedure she is to cover the dome in ceramic fibre and then apply your refractory mortar. Somebody has suggested to me here to make a refractory mortar and then add aluminium fibres in it and then apply to the complete dome as a way of strengthening it. Because I am in the middle of the build I can still decide whether to have another layer of bricks or whether to cement the whole thing and then paint it but as you can see from the picture this will be outside with no cover. Please give me every and any suggestions you may have this is my first time building anything like this.
I live in Italy but am English.

Many thanks to all.

Gerry

[Toomulla]

This is not a dome but a barrel vault. A dome if intrinsically stable a barrel vault less so and would benefit from buttressing to the sides. Another layer of brick will not make it necessarily stronger and will take longer to heat. I cannot understand how you propose to fire the two levels some more detail of how you envisage the fire / flame/smoke venting would help

[geraldevans]

I'll explain. Half way up will be a refractory shelf. The fire will be forced to heat up the stone passing towards the back wall then heating the dome and finally exiting at the front top. There will be 2 doors one for the bottom half and a second for the top. I'm just about to mix my perlite and cement mix for first coat!

[geraldevans]

I held off on the insulating layer as I thought I had better build the chimney first. I still also experimenting with a perlite mix. Have other people had problems mixing the stuff but I got a great solution by revelation and it's perfect now! So if anyone needs to know message me!

[deejayoh]

There have been other builders here with an oven design similar to yours. Most of the posts are complaints about difficulty getting the oven to temperature, as all of the heat from the wood goes up your flue. You might want to do a search for some of those threads. Maybe others can remember where they are.

[david s]

There are advantages in an updraft oven. There's no entry to have to work past and no smoke out the door at start up. This is presumably why there are some small ovens at Pompeii that have flues in the centre.They appeared to be in peoples homes unlike the large oven in the bakery which is a cross draft oven typical of the style built by most on this site. The downside of an updraft system is that more heat escapes out the flue and therefore fuel consumption is greater. You won't lose all the heat out the flue, but an updraft system will use about 25% more fuel than its equivalent cross draft cousin. If the oven is small the extra fuel used is hardly a consideration, but for a larger oven it's quite an issue. With the updraft system you need either a valve at the base of the flue so you can close it, or place a tile over the top of the flue pipe, otherwise when you open the door during roasting or baking with th door in place a lot of heat will be lost out the flue.