36" Pompeii in Indiana, US

[JRPizza]

If you have not cut your bricks yet have you considered a herringbone pattern for the floor? Folks had posted that an angled pattern helps keep the peel and any cooking utensils from easily catching on brick edges.

[GreenViews]

Thank you JR. I will be adding a layer of splits on top of the full layer I have shown and definitely do it with that layer!

[GreenViews]

Help, I may have goofed! To correct the unevenness, large gaps and minor crumbling in my CaSi layer, I decided to add a 4:1 perlite layer on top. About 3/4" only. As suggested, I plan to put bricks on a fireclay/sand layer on top of this. Instead of 5:1 perlite: portland I used 4:1 perlite: Acona medium duty refractory mortar. 12 hours later, there were soft and crumbly spots. I'm pretty sure I mixed up really good, maybe not enough water in spots? I sprinkled more of the refractory mortar on top and wet it with a spray bottle and trowled it in a little. Now it is pretty hard most spots, but on edges there are a few crumbly and soft spots still. The Acona product has a warning about portland, so perhaps it is similar to homebrew? Not sure. Should I have used just portland? How long should it take to set up? Am I being too impatient? With all the warnings I've read about portland chemically breaking down under heat over time, I was nervous about using it in the perlite layer right below the brick. How hard does this 3/4" layer need to be? Too many questions, but I'm nervous about the foundation for my dome which is why I tried to improve on the stability of the CaSi board in the first place.
Any advice? A) scrape it off and use it for insulation around dome later, forgetting about the heat loss through CaSi gaps and don't worry about stability of that B) probably good enough if your finger makes a small impression in it, but 2 blocks stacked don't, go ahead with clay/sand layer C) add more mortar to top or scrape off and mix in with more mortar or portland and re-apply. I'll do my best next work day if I don't hear back from anyone with advice. When I picked up another 350 firebrick today I also picked up some firestop 50 refractory mortar. Anyone know if that is better than the akona product? Thanks in advance and I'll go out and put my saw together now and cut my subfloor bricks and try not to worry about this yet hoping the right answer will come in time. https://photos.app.goo.gl/N539Z6rRNeVXL6Wd9

[GreenViews]

For others browsing, I came across this thread: https://community.fornobravo.com/for...ent#post423442 which seems to indicate that I'm being way too impatient with this cure time. I'm not sure I want to wait a week or two to start building my dome, but it seems to be getting harder all the time and maybe in 2 days (after the rain tomorrow) it will be hard enough to start the underlayment layer and first course of the dome without me scraping it off and redoing this 3/4" layer.

[P3 Stoaker]

G'day Greenviews and all,
Wow, I just read your post, unfortunately I cannot offer much help with your questions. I certainly agree though that a solid base seems essential as collapsing or crushing would cause catastrophic damage. I have also had it stressed to me here on the forum, not to be afraid to undo work and go backwards to get it right. I know none of us want to hear that but if that is whats required to get it right then so be it !!!
I am doing an oven a little larger, 21' 21/32" radius ( metric at 550 mm) but I'm considering a slightly lower dome centre, around 500 mm (19' 11/16"), or even 480 mm. The reason for this comes from a local oven builder and he claims with the centre that little bit lower performance is significantly better. 2 questions, firstly, I haven't put that idea to the many many years of experience here on the forum and secondly, how to build. This local chap builds for a living so needs to achieve quick results, he cant wait around too long for mortar to set before laying the next course. What he does is lay the first 4 courses and then builds a sand mould inside. This allows the dome to be completed quite quickly as drying isn't a problem. Apparently the inside mortar joints often need a little touching up which is done after the sand is removed.
If performing this build, or any with a somewhat lower dome I do wonder how to use the IT tool?? I think you could just shorten the length each course, and I think the tool will still set the correct angle each course. the length of the tool for the previous course is obviously known, and the final top course. Question will be how to evenly split the shortening of the tool each course.
Do you know where Russell posted the info about the dome vent?
Kind Regards
Greg

[GreenViews]

Greg, Thank you for your comments and feedback. I've read many comments about lower dome being better for cooking top of pizza specifically, so I guess we shall see Glad to have another builder at same stage with similar design ideas . I also decided to save my older, slightly harder used firebrick for near the top of the dome which I will have better heat transfer characteristics, might also help. After some drawings, I decided to go up about 1/2" from the recommended low dome build from the FB ver2 guide, mostly for IT stick reasons.

If you go back in my thread, you can see drawings I did to think through IT stick placement and the idea of just shortening each course. One problems was the brick face angle difference while indistinguishable at 0 and 90 degrees became a bit pronounced half way up the dome (45 degrees). That would change the physics between the courses in the event of mortar failure. Does it matter? good question. But I suppose an angle correction step could be added to the IT by way of a simple shim or with an angle adjustment on head of IT which might be hard to make in a sturdy fashion.

I figured if I were to just shorten IT, rather than fancy calculations (which I have skills to do) It would be more practical to just create a single plywood template of your exact desired dome arch minus 1/5" off bottom. Then cut it in thirds for later removal, reassemble and place inside your oven to one side of your IT which you could raise at the beginning of each new course on the back side of oven right next to IT to get proper IT adjustment for the new course in regards to cut and face angles. One could even create a number of lines on this wood arch template with lines toward true arch center. So I guess that would be a hybrid between forming and creating IT. As I write this, I'm now considering doing just this with height and angle adjustment each course rather than keeping part of my floor and sub-floor out during build!!! I like this solution better than a dual angle IT which I have also seen, but seems more complex adjustments.

The vent posting: They used auto breather vents. here is one location discussed: https://community.fornobravo.com/for...ii-build/page4

Other Low dome thoughts: I think I'll add at least small amount of pcrete buttressing even without a full soldier course which I decided against so as to not create an even wider (lower focal center) arch. The guy who did a large commercial lower dome oven (don't remember name at moment) has some serious pcrete buttressing with rebar, but that was a massive oven and massive span with full brick in arch. Amazing, but not what we are doing, lol. Interesting idea on the sand form inside. I'm going to try and build without supports and see how it goes. Time will tell if I change my mind, but I also have a bunch of Styrofoam here I could use if need to add later on top of a high platform inside oven.

My floor seems quite hard this morning, very different from yesterday. I'll test better when I get to work in earnest, but It is hard enough I am quite confident in keeping it below the floor/subfloor. Worst case is that around the dome outer 2 inches I could possible remove some and put new with higher ratio of refractory. I even have a little refractory castable I could use. This layer could be either insulating or non-insulating as I have insulation outside of this layer, so I think going with strength is better option for me here since I don't want to always worry about dome collapse or weakening because of my failure on this step. This is only a 3/4" layer, so burning through a little of the safe, but expensive product like the refractory castable for the outside 2" to ensure good dome support isn't going to break the bank for me. Does make me wish I had known my CaSi board would come in such a cracked, less than perfect state. I probably would have used half the width and just planned on a normal pcrete layer in addition but underneath it maybe. Or maybe I'm worrying too much about the CaSi strength. Not sure. I know I couldn't load all the bricks for my build on my little trailer that I use for 3/4 tonne hauling fairly regularly. A lot of weight in the dome!

[P3 Stoaker]

G'day Tom,
I've had a look at your previous diagrams and I think I see what you are saying about the brick course alignment. So in theory it would work to simply shorten the IT each course but the gaps would be a lot larger towards the top of the dome. Hmm I think I'm understanding the issue, but I don't really know of a solution. I do wonder though, talking to this local oven builder, his method is simply lay 4 courses, using a tapered brick but only side tapers. He lays with a 20mm (25/32) gap at the outside join (horizontal) of each course, including between the floor and the first brick. From there he transitions to a sand mould as I described earlier. I'm not necessarily saying I'm doing that or that I believe its the best thing. It is however an interesting method worth consideration and would eliminate the IT issues towards the top of the dome.
Apologies but I don't know what 'buttressing' is so can't comment. Glad to head your floor is hardening!! that would be concerning.
I had similat thoughts about covering my casil, 2 layers casil board, 2" with 1" of perlite but I was concerned that thickness of perlite was thick enough to, well hold together i guess??
Kind Regards
Greg

[GreenViews]

Update on my project: (I was taken away a few days from other life issues)

1. 4:1 non-standard perlite:refractory mortar layer and only 3/4". Even though I had seen this mix referenced as option in other locations online, it is not standard here and I was concerned about it's ability to hold together under the weight of the dome. I added it out of concern for stibility of my CaSi board, but perhaps this was worrying too much since I have not seen others here discussing issues with CaSi board structural integrity outside of moisture issues. This is to say that maybe one of the following steps was too cautious, but since I was using non-standard mix, I wasn't sure.
2. Dome support: To be sure I had good dome support, I removed 2.5 to 3" of the outside edge of the 3/4" layer and mixed up some castable refractory that I had purchased at Menards and didn't have a specific purpose in mind. I crumbled up the perlite layer I removed and added 1 part of this crumbled perlite to 1.5 parts of the castable refractory. I also added a little heat tolerant basalt fiber reinforcement. I didn't need the insulating value of this layer and I feel much more confident in the stability of my dome base now. I also found that the refractory mortar & perlite I took out would easily support the floor of the oven, so didn't go further. This will teach me for straying too far off the guideline But now good.
3. I assembled my saw and cut my sub-floor firebrick. This is the lower floor layer. I still have a split brick layer to go on top and will use herringbone pattern there. Thanks for the suggestions all!!
4. With my plan for neopolitan (low) dome, I needed a complex IT or needed to leave sub-floor out since my dome radius was below the floor level. I came up with a design for a complex IT that allows me to change angle of brick face and length of tool with each course. Other designs I saw had a hinge in the center and allowed you to adjust length of tool along floor and length of tool from floor to dome. Let us see if my design idea will work well but I'll show picture here of my early model.
5. Having come up with an IT design I was happy with I decided to lay the sub-floor. The dome and inner arch will all sit on this. I installed this over a bed of 1:1 fireclay: silica sand. I applied this wet and found that the moisture was being sucked out of it so fast from the lower layer that I needed to add more water for any workability with the tile trowel. I did my best to keep bricks level and tight, but I also have one more layer to further correct any discrepancies.
6. I set up a tarp cover and a work light for the nights I want to work later.
7. Completed other patio work yesterday.
8. Hope to start on first course today.

[GreenViews]

[GreenViews]

This evening I was able to:

• install wood floor that can be removed after build, but used to protect my subfloor and to anchor my IT to.
• Calculate cut then cut down my true radius pattern to blocked height. This pattern will be used to set the angle and height of my IT for each new course. (vs math which I have skills for, but not the experience to plan for mortar joints and unknown variables)
• Planned then cut all the bricks for my first course. I am cutting the tops a bit to have about 2" of straight joint and cut at a steeper angle so the second course (also a half soldier like the first course) will bring the dome back into the semi-circle that the first soldier threw off by going staight up rather than up at an angle.
• Planned for cut on top of the second course brick.

Tomorrow (I hope)

• mortar in first course
• cut second course and mortar in place

[Jamie Dowdall]

I'm planning a low dome elliptical design as well. Will be following closely to see how your IT design works. The swinging hinged design is what I have in mind.

[GreenViews]

I just read this from the FB plans v2.0.

Because the Tuscan design has a larger oven space above the door opening, it is more efficient at holding heat, and uses less wood.

Higher dome more efficient at holding heat and uses less wood. I guess I was so focused on building the best pizza oven I overlooked this aspect. I'm pretty committed to the low dome now though. I hope I don't regret it. Anyone know if they are talking about another log or two or if it is a huge difference?

Edit: I did find this discussion that says you will love what you build. Sounds true. Still, didn't find reference to comparison of fuel needed: https://community.fornobravo.com/for...olitan-profile
Then there is mklingles discussion of Mathematical analysis of dome geometry, which I t hink is missing a couple of images referenced. https://community.fornobravo.com/for...ometry?t=15292

Thoughts on extra fuel needed for low dome?

[GreenViews]

Here is a timelapse video of laying my first course. I couldn't upload it here it seems. https://photos.app.goo.gl/R7T6Svt15dqyiTTV6

[UtahBeehiver]

Looks like you are making headway, couple questions and one tip. The gray bedding, is it sand/clay mix or mortar? Looks like a premix was used on the half soldiers. Typically the bottom of the first course is not mortared to the floor so the dome and floor can expand and contract independently. But if it was mortared, it is what it is. Just to confirm, the premix is airset, Some builders, by mistake used heat set, the oven temps do not get high enough to set mortar. Tip, on the very last brick, this is getting close to what we call a chip, spread the adjustment over a couple bricks and do all you adjustments on the front half of the dome with your best bricks and work on the back half of the dome. Once the dome is done people really can only see the back half of the dome when cooking.

[Jamie Dowdall]

Here is a timelapse video of laying my first course. I couldn't upload it here it seems. https://photos.app.goo.gl/R7T6Svt15dqyiTTV6

The timelapse is awesome! Looking good.