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Discussion Starter · #1 · (Edited)
It's a little different than most so I'm hoping someone can give me some insight. This is what i'm working with. I have the structural pad poured but not the insulating pad and the bricks are all full size because it's just for layout at the moment.





The oven is going to be quite small I realise that and am OK with it. I'm sure i would be happier with a larger oven but I'll be glad to have anything really. That said, I want to make it as large as possible. So, would a 2.25" thick (firebrick laid as a shiner, or a header) be enough. That while it wouldn't be a huge gain it would be better than nothing. the other thing I could do would be 3"= 1/3 of a stretcher or 1.5 shiners, not fun all that cutting but that extra 1/3 of strength seems significant to me. The narrower i make the walls the taller I'll have to make the rise of the vault to lessen the thrust.

next...On advice from you guys I've made the floor of the oven quite high, it's @ 44" at the structural pad and if i go 3.5" of insulating pad and another 2.5" of firebrick and fireclay, that brings it to 52" . That seemed alright on paper but 44" is seeming pretty high right now (granted I'm 4-5 " below finished grade right now because flagstone isn't in yet so maybe that's it but even when i stand on the pad it seems high). So IF i feel like the floor of the oven will be too high and i want to lower it a couple inches do you think that 2" of perlcrete would be sufficient or what about going with splits for the floor?

And lastly. As you can see to try and save room i've got the front as a barrel vault and the back as a dome....so what I'm wondering is am I out to lunch? Also, should i make the rear a dome or build it up straight and bring the arch of the vault into it? it will mean some compound angle cutting, mostly by guess and by gosh but I'm into it now.
 

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Have never built one so no advice for you bud sorry, but when I do I will be going of the advice given in these posts, look forward to the progress pics and advice.
 

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When ya finish it think up a ball park price of what you would charge to build one.
 

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If that is the cross section laid out (as well as the plan), I would bring the spring line down to one brick high, unless the floor is inside, in which case bring it down to 1-1/2 brick. 2-1/2 is fine for an occasional use oven, no problem there. If what you have ends up too high, build a step in front; best of both worlds, no bending to look in, and you can stand on the step to work it.

I think you should definitely go with the dome back wall, someone has to the first. I have considered it myself.
 

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Discussion Starter · #6 ·
No it isn't a cross section but it would be close. Haven't thought tons about how much to raise the walls before the spring, somewhere between 4.5" and 9". if the dome rises by 8" (what the 'rise" of that semi circle is now) that would might work for a 6.75" wall. Give me enough room for a leg of lamb but not too much volume to heat
 

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... Give me enough room for a leg of lamb but not too much volume to heat....
Dam does that sound good.....Great idea...:thumbsup:

Just build the thing & cook in it...:thumbup:

Check these guys out. It's a mobile true wood fired oven. They make the most incredible pizza. Not all that big either, but they do crank out the pizza. I'll see them this weekend and ask about other goodies in the oven....

https://www.facebook.com/pages/Rosies-Inferno-Mobile-Wood-Fired-Pizza/268536845382
 

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There is a specific ratio for the dome height and the door height that is critical for a good burn. It is something like 1.6-1. I made mine with a 16" high dome and a 10" high door and it burns fine. I have a barrel to the back but a dome in the back sounds great.

If you can lay it out to cook two pizzas at a time it is good for when there are lots of people over. The insulation is important if you are going to bake. For just pizzas a smaller insulation is OK. I think I made mine around 40" high. A bit low but easy to see the pizzas from a step back. You will get used to whatever you end up with.

I need to keep a fire going to cook the pizza, kind of like a broiler. So remember to leave enough space for the fire. I think I added a bit to the end of mine at the build to make room for the fire.

Remember done is right. There are lots of blogs on building and several books. One key that I kept in mind is to keep the oven part completely isolated from any structure. You need to allow for expansion and contraction because the bricks will glow with heat! I separated everything with the perlite. I hade to rebuild the entry arch with refractory cement as the fire clay did not hold up so do that the first time.

Good luck and enjoy. I will share my dough recipe when you are closer.
 

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Discussion Starter · #9 ·
Thanks. 63% or /1.6 opening to dome height is the number that Forno bravo uses and all the guys who have built them adhere to that and it seems to work well, so i won't monkey with that.

i agree, done is done and better than not done. I will have a minimum of 3" of perlcrete insulation at one or 2 spots because of the semi-circle inside a triangle business but I'll mostly have 5" around the walls and then as much as i can on top.

Bond breaks will be a for sure. And i'm hoping to be able to fire 2 10" pizzas and maybe 1 8" but even if i can do 2 8" at a time that gets a bunch of kids done and fed fairly quick and the grown ups can just wait and drink

we''ve been doing pizza in the oven most fridays for about 4 or 5 years so I have a decent dough recipe but post up your's I'm sure the wood fired dough @ 700*+ will be different from the oven baked at 450
 

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It's a little different than most so I'm hoping someone can give me some insight. This is what i'm working with. I have the structural pad poured but not the insulating pad and the bricks are all full size because it's just for layout at the moment.





The oven is going to be quite small I realise that and am OK with it. I'm sure i would be happier with a larger oven but I'll be glad to have anything really. That said, I want to make it as large as possible. So, would a 2.25" thick (firebrick laid as a shiner, or a header) be enough. That while it wouldn't be a huge gain it would be better than nothing. the other thing I could do would be 3"= 1/3 of a stretcher or 1.5 shiners, not fun all that cutting but that extra 1/3 of strength seems significant to me. The narrower i make the walls the taller I'll have to make the rise of the vault to lessen the thrust.

next...On advice from you guys I've made the floor of the oven quite high, it's @ 44" at the structural pad and if i go 3.5" of insulating pad and another 2.5" of firebrick and fireclay, that brings it to 52" . That seemed alright on paper but 44" is seeming pretty high right now (granted I'm 4-5 " below finished grade right now because flagstone isn't in yet so maybe that's it but even when i stand on the pad it seems high). So IF i feel like the floor of the oven will be too high and i want to lower it a couple inches do you think that 2" of perlcrete would be sufficient or what about going with splits for the floor?

And lastly. As you can see to try and save room i've got the front as a barrel vault and the back as a dome....so what I'm wondering is am I out to lunch? Also, should i make the rear a dome or build it up straight and bring the arch of the vault into it? it will mean some compound angle cutting, mostly by guess and by gosh but I'm into it now.
44" was recommended as a finished hearth height, Sean. But it sounds like you will be in good shape after the patio goes in.

You won't need to raise the height of the dome to counter thrust if you put a reinforced cladding over it. It will also add some mass, but you're talking about a fairly thin oven dome anyway.

I'll second the domed back, I think it would look cool. I've seen it done with fireboxes but never on an oven vault.
 

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Thanks. 63% or /1.6 opening to dome height is the number that Forno bravo uses and all the guys who have built them adhere to that and it seems to work well, so i won't monkey with that.
theres a bit more flexibility than that. 60%-64%

i agree, done is done and better than not done. I will have a minimum of 3" of perlcrete insulation at one or 2 spots because of the semi-circle inside a triangle business but I'll mostly have 5" around the walls and then as much as i can on top.

Bond breaks will be a for sure. And i'm hoping to be able to fire 2 10" pizzas and maybe 1 8" but even if i can do 2 8" at a time that gets a bunch of kids done and fed fairly quick and the grown ups can just wait and drink
having a smaller oven roaring, I doubt you will want two pies going at once...your better be fast on the peel if you do. 90-120 seconds isn't that long to wait after all...
we''ve been doing pizza in the oven most fridays for about 4 or 5 years so I have a decent dough recipe but post up your's I'm sure the wood fired dough @ 700*+ will be different from the oven baked at 450
Forgot to mention, you should have more than 2" of perlcrete under the hearth...4" is a good minimum. If you use ceramic board or foam glas that's a different story..2" is fine.
 

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Discussion Starter · #12 ·
Forgot to mention, you should have more than 2" of perlcrete under the hearth...4" is a good minimum. If you use ceramic board or foam glas that's a different story..2" is fine.
Thanks for that. I'll go for 4".

I thought when we were talking in Bytors thread that everyone was saying that 48" was too low and they would have rather had the floor higher
 

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Discussion Starter · #13 ·
Weird, i can't find the thread where i talked about floor heights. I thought it was Bytors or maybe yours but I don't see it in either one. 44", where it is now seems like it would be a good height
 

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Discussion Starter · #14 ·
You won't need to raise the height of the dome to counter thrust if you put a reinforced cladding over it. It will also add some mass, but you're talking about a fairly thin oven dome anyway.
Ok, so a 9" wall with an 8" rise for the vault...sounds good or too much...or not enough?

reinforced cladding meaning perlcrete with wire? or just perlcrete/vermicrete?
 

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Ok, so a 9" wall with an 8" rise for the vault...sounds good or too much...or not enough?

reinforced cladding meaning perlcrete with wire? or just perlcrete/vermicrete?

Sounds ok to me. There a lot of forgiveness as far as actual shape goes.

No, perl/vermicrete won't make a structural cladding, too friable.....but a reinforced layer of fire mortar or refractory will do the trick.
 

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Discussion Starter · #16 ·
Maybe I'll make the dome height work to a good opening size.

How thick a layer do you think i'd need to add some structure to the thing. heatstop 50 isn't cheap. Would i need wire also do you think?

I'm kind of leaning towards a a 3" structure. I'd still have a reasonable amount of insulation at the thinnest spot and while it's more cutting I'm just a bit nervous about an arch made of such flimsy material.

So long as i know that I need to do min 4" of insulating slab i can carry on with that and lay the floor anyhow
 

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Maybe I'll make the dome height work to a good opening size.

How thick a layer do you think i'd need to add some structure to the thing. heatstop 50 isn't cheap. Would i need wire also do you think?

I'm kind of leaning towards a a 3" structure. I'd still have a reasonable amount of insulation at the thinnest spot and while it's more cutting I'm just a bit nervous about an arch made of such flimsy material.

So long as i know that I need to do min 4" of insulating slab i can carry on with that and lay the floor anyhow
Make your own fire mortar out of lime, portland, fireclay and sand...guys on FB go 1:1:1:3 but I think it's way too rich. I went close to 5 parts sand, and I cut the portland portion in half. 1/2"-1" will be just fine for cladding.
 

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Use the scratch refractory mortar for the cladding. I have made cubes and tested them in both the oven and bonfires, they do just fine. For laying the brick, however, Heatstop is worth the money. You can do 4" vermi/perlcrete then stucco over that for an igloo shape or as a monocoque shell if you do not want the extra cladding on the oven itself.

Some reading I have been doing leads me to believe that there has been a misunderstanding at what temperature portland cement reverts to it's constituent parts. I have had portland plant lab engineers tell me "500 degrees" is when portland cement begins to fail, but I did not clarify centigrade or Fahrenheit. Some of the recent articles I have read give the number as 500 centigrade.
 

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Discussion Starter · #19 ·
Oh yeah..it's 500 C, not F. 1200 F is what the original impure limestone needed to burn at to turn into whatever it's equivalent of quiclkime as opposed to 800F for marble or chalk. but i don't think it's just failing, it's it's ability to expand and contract and not crack, I think that up to 700* lime probably has the advantage over portland

That said a friend has an outdoor rotisserie that is made of brick and type S and the mortar is in terrible shape 15 years later and the bricks are cracked like crazy. Still useable though
 

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Discussion Starter · #20 ·
How much of a covering of this mortar would i need to add strength? 1/2" anyway....I might still do the 3", who knows it could be less work in the long run
 
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