40" pompeii, first time builder

[david s]

Try looking at the many cast oven builds on this forum
They are in the "Other Ovens" section and many well documented builds with the kind of design you want.
Here is an explanation of buttressing. Because of the thermal expansion factor don't even attempt flying buttresses, but the principles of normal buttressing are the same.

https://www.thoughtco.com/what-is-a-...ttress-4049089

[totalnewbie]

Hey all,

I think I can explain my logic.

-- I am looking to build something that will last for a long time, and I don't want to worry about cracking when I use the oven. So that rules out a 3:1:1:1 cast in place.
-- I don't really want to spend $4,000 on a kit.
-- I would like to experiment with Pizza Napoletana, 900F, 60 second pizzas and all that Naples stuff. It sounds fun and I really enjoy "real" Naples pizza. I read pizzamaking.com and I've been to Naples quite a few times.
-- I've watched the videos from the Australian company that makes pre-cut hemisphere dome brick ovens -- 18" high for a 36" oven using a fixed trammel and tapered, single and double trapezoid bricks. That's too high for what I'm shooting for.
-- The Casa2G 36" oven dome is 15" high.
-- The Gozney Core 39.3" oven is 15" high.
-- Large Naples pizza ovens built for restaurants have very low/aggressive domes, though I don't know the ratio. Acunto is built using a steel banded dome set on soldiers. I've seen lots of images of other Naples ovens being built, but I've never seen a clear depiction of a metal band or chain. I would love to see one.
-- I know what a buttress is. I've spent a lot of time in European cathedrals, and I've even taken a couple of architecture classes. :-)
-- The Scott oven is buttressed with inches of concrete poured into an external plywood form. A friend built one. Though I don't want a massive bread oven.

It seems like my goals are not strange, but rather pretty mainstream.

I would like to build a 36" oven with the first course an upright 9" soldier, with an internal dome height of, let's say 14-15". That won't fall down if I don't chain the soldier course together. I don't know. Maybe what I'm trying to do really is impossible.

I guess my question is whether someone has already built this oven using bricks in the 20+ years of the Forno Bravo Forum. haha. And if it's still standing. It would be great to follow someone else's lead who had the same design goals in mind.

Here's a rough sketch of what I'm thinking.

[david s]

Have you ever fired or cooked in a wood fired oven? If not then you are probably over worrying about problems as well as being oversold on some advantages. The best teacher is experience and starting small and cheap is an ideal way to learn.
I had a request from a customer/friend who wanted a taller oven to fit in larger roasts than the ones I manufacture. as this was their second oven (of mine) for a new house they built.
I approached the problem with some trepidation, but settled on a design that involved casting a 50mm (2”) ring upon which my standard hemispherical 540mm (21”) cast refractory oven sat. This raised both the internal height of the dome as well as the height of the door by 50mm (2”)
If you like you can do the math and see that it threw out the door to internal height out a lot. Of course I was a bit concerned about how it would fire and cook. Surprise, surprise, we could not notice any difference in either the way it fired or its cooking performance. Maybe if we did some careful and exhaustive testing it might show up some small differences but certainly nothing we could detect from using it in the normal way. This oven which was built in 2007 with some funky tiling on the stand and a nice mosaic of Positano on the front, still is in good nick and pumps out 2 minute pizzas all night.

[totalnewbie]

Hi David,

How interesting. I didn't know you had a pizza oven manufacturing (building?) company. That's exciting! What's the name? Do you have a website?

Do you make cast ovens or brick ovens? If you make cast ovens, what material do you use?

What bricks do you use for the floor? And where do you get them?

Fun stuff!!!

Yes, I have cooked in brick ovens many times through friends. I've also lived in Italy and used friends' ovens there, and of course seen a lot of pizza ovens and eaten a lot of good pizza. I've also burned a lot of crusts and getting excellent pizza from a very hot oven is really tricky. Good pizza from a 700F oven isn't as challenging, but shooting for great pizza at 900F is another animal.

I would like to get this oven right -- it would be great to hear some details on how you do it yourself!

Thx!

[david s]

No you can’t have details of my business because that is outside the rules (and the spirit) of the Forno Bravo forum. I don’t export, advertise, or employ additional labour, so I’m not in competition with FB. Most of my builds are in our city which keeps me busy enough.

Regarding the firebricks used in the floor, I source them from India and I use a proprietary castable refractory enriched with three types of fibres that perform different functions.

[totalnewbie]

Good point, that makes sense, and how fun. I hope you enjoy it.

I guess my general question is still there. Has anybody built a Naples style oven using brick who could comment or who I could learn from? I think what I am trying to do is pretty reasonable. Forums are a funny thing. There's a ton of historical content, but it can be difficult to find the right information in the archives. And many of the people who built ovens in the past are no longer active.

Thanks again for your input David. It's been really helpful!

I'm off to do more research. :-)

[david s]

The way this forum is constructed leads to quite a bit of difficulty finding what you want. The search function does not work nearly as well as just going to your search engine, Google for instance, and typing in what you're looking for as well as Forno Bravo. You'll get plenty of hits with this method
Also try here...

https://community.fornobravo.com/for...tions#post6108

and here

https://community.fornobravo.com/for...219#post183219

[totalnewbie]

Those are fun! Thanks. It feels like a time capsule in the somewhat early days of the Internet user groups. Good stuff.

If I chicken out, and build a 3:1:1:1 castable dome over a sandcastle -- what are the three additives. I think I can guess two -- poly fibers for burnout to let steam escape and not make cracks, and maybe stainless for structural integrity in the event of a bad crack. But I'm not so sure on #2, because of different expansion rates of 3:1:1:1 and stainless, and I have no clue for the third type.

Inquiring minds.....

[david s]

Because of the expense and the difficulty in applying a mix containing needles, especially with no experience of the mix and the method, I’d not recommend their use. But either, or both AR glass fibres or basalt fibres which have decent strength at our service temps and melting points well above, are good additions for strength enhancement.

[totalnewbie]

Hey all,

Thanks for the input so far. I've torn up my backyard and things are getting serious. I need to design the foundation for the oven and a grill. I'm planning on using concrete blocks for the oven stand, about 36" of countertop, a 36" built-in grill and a small counter on the other side of the grill. I also need to come up with the block count before I order with Lowes, and start excavating for the foundation. There are some great outdoor kitchen designs to borrow from here, so thanks to everyone who build those!

The oven is going to be covered in what I think of as "stucco". But I'm not sure what the right term is, or what to buy from Lowes or Home Depot. The English (Australians?) call it Render. What is Render?

If anyone can explain what I'm looking for, and where to get it (and what Render is) I would really appreciate it! The shape will be Igloo/Dome. I've been reading David's comments on Render in other posts, and I know some, but not enough at this point. I was leaning toward three ceramic blankets (despite the cost), with a chicken wire from and..... "stucco".

Is there something I can read somewhere?

Thanks for the input.

[david s]

Render (English) stucco (American) but the same thing.
This thread might help
https://community.fornobravo.com/for...938#post456938

[totalnewbie]

Thanks.

*****************

The addition of perlite or vermiculite to any mix severely compromises its strength and applying a strong render over blanket is difficult because the blanket is rather springy. My solution (and there are many ways to go) is to cover the blanket with a very lean (10:1) mix which results in an insulation layer with equivalent insulation value, per thickness, as blanket.
I find a combination of perlite and vermiculite (50/50) works better than either of them alone.Once this has dried I apply a 4:1:1 sand, lime, cement render enriched with AR glass reinforcing fibres about 15mm thick. This eliminates the need to use chickenwire.The addition of perlite or vermiculite to any mix severely compromises its strength and applying a strong render over blanket is difficult because the blanket is rather springy. My solution (and there are many ways to go) is to cover the blanket with a very lean (10:1) mix which results in an insulation layer with equivalent insulation value, per thickness, as blanket.
I find a combination of perlite and vermiculite (50/50) works better than either of them alone.Once this has dried I apply a 4:1:1 sand, lime, cement render enriched with AR glass reinforcing fibres about 15mm thick. This eliminates the need to use chickenwire.

*****************

Let me be sure I have this right. I am doing a stucco layer that is outdoors and needs to be waterproof and will be painted.

You recommend doing a 1" layer of 50/50 vermiculite and petite, in a 10:1 mix by volume with Portland cement. That layer is more rigid than doing the stucco/render directly on the insulating blankets, and it eliminated the need for chicken wire. I get my rough igloo/dome shape from that layer, not chicken wire over the ceramic blanket The insulating value isn't high, but it makes doing the stucco layer easier to work with.

Then, I use a one-coat stucco (either 4:1:1 sand, lime, cement with fibers, or a pre-made commercial stucco with fibers) to finish the igloo shape before painting.

Is that right?

Thanks!

[david s]

Almost, but a 10:1 vermicrete does have a high insulation value (see table) around the equivalent to blanket if a lean 10:1 mix is applied.
Commercial cement renders (stucco) have some water proofing added which makes them partially waterproof, but these days, at least in Australia, they no longer contain lime (I believe this is because of safety reasons as lime is quite caustic and can cause skin irritation and problems if you have a cut on your hand), which does impart some elasticity and crack healing properties. I actually make my own render mix by using half commercial render and half the 4:1:1 mix, then add the reinforcing fibres, that way it gets the benefit of some waterproofing and some of the benefit from the lime addition as well a making the mix somewhat cheaper. Drying fires should be done after the vermicrete layer, but before the outer render shell is applied.

[totalnewbie]

Nice. Thanks.

That's right. You can't beat an extra 1" of high quality insulation. More is never enough! Maybe I can be cheap and only cover my dome with 2" of blankets.

[totalnewbie]

Hey all. We've formed for the concrete slab. Getting exciting. I've been looking at videos, and I see that some builders put aluminum foil both over the floor insulation -- before the firebricks and over the blanket insulation -- before the stucco. I am guessing this is to make sure the insulation stays dry and waterproof.

It doesn't seem like it would be expensive and not take a lot of time. But is either of them worth it? Or something else.

Thanks!