Dome is done, now the insulating layers

[Daron]

Ok, I had to change my initial base design based on advice I got here previously. So floor is 6 inches concrete topped by 5.5 inches portland/vermiculite at 6:1. Dome is 4 inches thick fire brick, 28.5 inch inside diameter and 16 high. Opening is 15 wide and 10.5 tall. Chimney vent inside is 3 by 7 inches. Installed wire tabs sticking out of external dome to make attaching insulating mat and chicken wire easier. My questions are: I have half a bag of fireplace mortar left. Skim coat dome with it to use it up or no benefit? Biggest question is I'm tight on space from dome edge to platform edge, 3 inches. My plan is for two layers of one inch mat then one inch of rendering and that will get scratch coat of thin set using acrylic admix with pebbles rather than tile covering to improve water repelling but will likely add a simple single pitch roof shedding water towards rear.
OK Fellows, don't let me screw these next steps up.....

[Sixto]

Skimming th dome will add more mass to heat up and also retain more heat, it won't make much difference as far as insulation goes. If you want/need more space for render, you can slide a thin sheet of some stiff, durable material around the perimeter of the dome base, and under the fiber blankets to extend the base for the render. Two inches of fiber with no perlcrete is better than one inch, but most people add a layer of perlcrete to increase insulation, round-out the shape and give a stiff underlayment for the render,,,

[fox]

Looks like a nice job so far, personally I would work out a way to extend the shelf area around the dome and use 4” of insulation.
Two inches will allow you to successfully use the oven although the the outside plaster will still get pretty warm, but four inch will work much better and hold the heat a lot longer.

[david s]

I have seen other ovens that extend out beyond the footprint of the supporting slab. Not only does it look really odd it makes the application of those last layers really difficult.If adding an extension to the slab you will need to drill into the sides of the supporting slab so you can pin it with steel bar.

[fox]

Ha ha thanks David, that is my standard style, I have built many just like that!
in this case sixto only needs to extend a few inches and I think it would look great!!!

[Pizzarotic]

Biggest question is I'm tight on space from dome edge to platform edge, 3 inches. My plan is for two layers of one inch mat then one inch of rendering and that will get scratch coat of thin set using acrylic admix with pebbles rather than tile covering to improve water repelling but will likely add a simple single pitch roof shedding water towards rear.

That is what I would do, rather than extending the base. You could add 3" blanket to the top half of the dome where it will be more effective or just stick with 2" as this will be adequate with reasonably good performance.

[Daron]

Progress! Made my own door. Wrapped dome completely in two full layers and a third layer over the top with one inch thick Forno Bravo mat. Started my first curing fire and getting smoke out the front as well as up chimney. Should I go one more row of bricks on chimney height or should I just expect some smoke out the front due to shallow depth of alley.
For an initial layer of rendering can I make a mixture of the leftover half bucket of refractory mortar and the left over Portland and vermiculite. If the answer is NO then these products just go to waste. I plan a layer of stucco, preferably a waterproof version if I can find it locally then that gets skimmed in thinnest that gets mixed with Polymer addative for water proofing then pebble covering for it's decorative layer.

[Pizzarotic]

Wait till after you have finished curing and see how it goes when fired to cooking temperature. For the rendering, use your leftovers. I would do a coat of vermiculite and portland in 10:1 with .5 clay or straight 8:1 then shape your dome once it's dried. Then finish with a skim of the refractory mortar for a smooth finish.

[david s]

Progress! Made my own door. Wrapped dome completely in two full layers and a third layer over the top with one inch thick Forno Bravo mat. Started my first curing fire and getting smoke out the front as well as up chimney. Should I go one more row of bricks on chimney height or should I just expect some smoke out the front due to shallow depth of alley.
For an initial layer of rendering can I make a mixture of the leftover half bucket of refractory mortar and the left over Portland and vermiculite. If the answer is NO then these products just go to waste. I plan a layer of stucco, preferably a waterproof version if I can find it locally then that gets skimmed in thinnest that gets mixed with Polymer addative for water proofing then pebble covering for it's decorative layer.

Don’t mix your refractory mortar with lime or Portland cement. They act as accelerants and will shorten the already limited working time of the refractory mortar to such an extent to make it unworkable.

I don’t think you should add any more brick to you chimney because it is sitting on top of an arch that is not braced or buttressed. The usual method is to use a stainless flue pipe that is lightweight compared to the weight of a brick chimney. The problem is exacerbated by thermal expansion of the bricks which can increase structural weakness.

[Daron]

Got er done and I'm cooking! Holds heat well. Making my own dough. Better with every cook.

[Giovanni Rossi]

Good looking pizze!

I'll be finishing my build in the spring and have been thinking about oven management. Maybe the angle is deceptive, but it looks like you have a pretty large fire going. Are you firing for retained heat cooking and just baking one pizza at a time in the front? A lot of the fellows on the forum discuss maintaining the fire on the side while baking 1 or 2 pies and moving it from side to side to recharge the floor when having a party. Also in this scheme some advocate building up the fire in the back before moving it to one side.

I'm thinking most of my sessions will be a couple pies followed by bread, etc. the next day. Maybe the fire location distinction is irrelevant in this case??

Congrats on finishing. Must have been a great feeling.

[Daron]

Good looking pizze!

I'll be finishing my build in the spring and have been thinking about oven management. Maybe the angle is deceptive, but it looks like you have a pretty large fire going. Are you firing for retained heat cooking and just baking one pizza at a time in the front? A lot of the fellows on the forum discuss maintaining the fire on the side while baking 1 or 2 pies and moving it from side to side to recharge the floor when having a party. Also in this scheme some advocate building up the fire in the back before moving it to one side.

I'm thinking most of my sessions will be a couple pies followed by bread, etc. the next day. Maybe the fire location distinction is irrelevant in this case??

Congrats on finishing. Must have been a great feeling.

Giovanni, It's a learning curve. I light my fire in the front to get a huge pile of coals to heat the floor. My floor is over 11 inches thick so I allow over an hour to heat floor then push back to burn the dome clean. I have been letting floor cool back down to 650-675F. I originally pushed coals to side and I have cooked two at a time but last few firings seemed easier to cook 12 inch pies one at a time. I have cooked 9 pies in an evening and we would sample slices as the creative creations came out. Next will be to experiment with retained heat and cast iron pan cooking. Damn, these pizzas are good. I can rival any local artisan pizza shop and I've tried them all in the name of research. Making my own simple dough but all work to improve that as time goes on.

Daron

[Lotus19]

Hi Daron,

I sent you a message a few weeks ago -- did you get it?

Thanks,

Joe

[Daron]

Lotus19 Just sent you a reply in messages