Corsair's 42" Pompeii Oven Mk 2

[RandyJ]

Hey Corsairmo I completely understand things coming up and delaying projects. I was delayed 5 years before I started mine. Good luck and I look forward to seeing what you do.

Randy

[Corsairmo]

Hey Corsairmo did you get started yet? I also recently got started on number 2. Took me 5 years to get around to this but being unemployed during covid put a bit of a damper on me doing things I wanted for me. I also learned a lot of lessons and am trying to streamline my building process this time. I nearly went for a pre built oven but shipping and hiring a crane to set it in the back yard was more money then I paid for the brick kit I got shipped to me. I can't wait to see what you end up building.

Randy

Hey Randy! I haven't done more than dream about it since I started this thread. Unexpected home repairs and slightly-expected knee surgery have led to postponing actual work on the project until later this year or next spring. I'll be sure to post as I go!

[RandyJ]

Hey Corsairmo did you get started yet? I also recently got started on number 2. Took me 5 years to get around to this but being unemployed during covid put a bit of a damper on me doing things I wanted for me. I also learned a lot of lessons and am trying to streamline my building process this time. I nearly went for a pre built oven but shipping and hiring a crane to set it in the back yard was more money then I paid for the brick kit I got shipped to me. I can't wait to see what you end up building.

Randy

[edonovan]

Thanks edonovan, it was hard to leave the oven and especially since I have no idea of the new owners even use it (though I did leave three pages of instructions for them )
But life takes precedence over our attachments sometimes.

I will admit some relief at the chance to build a second one, I knew, and know, I can do better, and I just plain love to build things.

LOL.. 3 pages of instructions!! That is something I could see myself doing! That or a full blown Youtube tutorial...Life definitely does take precedence and I can 100% relate to the "relief to build another" Enjoy the build!

[SableSprings]

Great review of lessons learned. One additional lesson for me was how insignificant a couple bags of mixed concrete looked in my hearth slab pour. I'd never consider doing it that way again...way better hiring a cement truck to come in (if at all possible ).

As to the ash dump slot, I have really enjoyed and appreciated the ability to pull ashes into a bin attached under the slot. Being able to clean out the ash with minimal mess in the surrounding area and letting me reduce the number of carry-outs is fabulous. I've honestly been very surprised how few builders incorporate the slot/storage bin design in their ovens.Very simple to include a void form made of a chunk of Styrofoam in the slab form setup. I also like that my ash slot is one brick wide so the ash falls easily into the container below.

Again, I envy you being able to apply all your lessons learned on this next build...enjoy the ride!
Mike

[Corsairmo]

Thanks edonovan, it was hard to leave the oven and especially since I have no idea of the new owners even use it (though I did leave three pages of instructions for them )
But life takes precedence over our attachments sometimes.

I will admit some relief at the chance to build a second one, I knew, and know, I can do better, and I just plain love to build things.

[edonovan]

You are quite the determined individual!! Not too sure I could sell this house, simply because of the oven and our outdoor kitchen...lol and I don't know if my wife could endure me building another one . That being said!! I completely agree on several aspects, 42" is a perfect size, corner build has proven to be awesome!! The oven has definitely has become a focal point of parties/cookouts and late night drinks for two, and the steel "duravent" chimney is great. Looking forward to following the build process and "upgraded" build procedures/additions!

[david s]

I agree. The time saved by making rough cuts for the outside of the floor bricks more than makes up for not being able to replace them. It’s only the bricks in the centre that are likely to crack or spall and provided you lay the floor loose you can still change them easily. If you use medium duty bricks for the floor there shouldn’t be any spalling or cracking anyway.

[Corsairmo]

Thanks David, that's kind of a "no duh" solution lol that should have been staring me in the face Based on my original oven, I can't imagine a situation where I'd need to replace a floor brick along the edge of the oven as there is just so little wear and contact there. In fact I can't really imagine needing to replace a floor brick in general, even after slinging dutch ovens and other cast iron cookware around inside of mine, but I'm sure situations present themselves.

My thought for having the floor inside the dome was more about the thermal mass difference between the heavier duty bricks I'll be using for the floor verses the lighter duty I'll be using for the dome. I was completely satisfied with the thermal mass of the lighter bricks, so I was wanting to minimize the heat soaking effect of the denser bricks around the hard-to-heat edge of the oven. But I think I'm overthinking it a bit and the concern is likely trivial.

[david s]

Setting the first course as soldiers (bricks standing on edge each one behind the other has some disadvantages in structure. Given that the weakest point of a hemisphere is at its base ( think of the strength of an eggshell if cut in half). As inner oven cracks always start at the base, having a vertical mortar coarse double the usual height is asking for trouble to begin right there. Far better to have two half bricks laid on bond (staggered) before leaning in.
There’s no difference between dome outside floor and dome inside floor if the IT begins at floor level. The advantage of dome over floor is that the floor perimeter cuts can be pretty rough, a big time saver. The disadvantage is that it would be almost impossible to replace a floor brick that has a dome sitting on top of it.

[Corsairmo]

I would revisit whether you want to do full soldiers on the first roll, maybe consider half soldiers or even half headers to reduce the outward pressure from the dome.

Thanks for the welcome back! I love your photo album by the way! I was just noticing that advice today on a forum post. I did half course on top of the floor last time, but I see lots of folks advocating for the floor to be inside the dome. If folks inset the floor inside the dome, how do you get any height for that first soldier course?

[UtahBeehiver]

Welcome back to Mk2. There have been quite a number of member improvements to the building process since your original build. You will just have to root around to find them or if you have a specific question post to your thread. I would revisit whether you want to do full soldiers on the first roll, maybe consider half soldiers or even half headers to reduce the outward pressure from the dome. I placed TCs in my build but to be honest, I never use them anymore, just the cheapo laser gun. Good choice on more insulation.

[Corsairmo]

Hello Everyone,

Welcome to my second effort into building the best pizza oven possible! My first build is rather haphazardly chronicled here:
https://community.fornobravo.com/for...2-pompeii-oven

I'm in the very early stages of planning my next oven (read: we are planning on buying a house this Spring) but as I dusted off my old notes and spreadsheets I wanted to talk about the things that I would do differently the second time around.

So this first post is meant to be a list of lessons learned from my first building experience, both good and bad. I'm going to list them out in roughly my order of significance.

1. BUILD THE OVEN! I built my original oven on the cheapest shoestring budget (both financial and time-wise) you can imagine for a busy father of four running his own business. There were significant compromises throughout the design and build process. The biggest factor in choosing the time to build was that my wife had graciously offered her support to the project after nearly 12 years of waiting and dreaming. It felt like now or never. Turns out, the oven was an almost overnight hit with our entire family. The versatility, fun, and utility of the oven took my wife from put-upon, but wonderful, supporter of her husband’s crazy oven obsession to small playful scuffles over whose turn it was to be the pizza slinger for the night. The kids love everything from pizza to breads, to steaks, to making perfect smores on the door landing (seriously, hang-outs and playdates have been planned around this feature). We all love it, and when we moved and started contemplating housing preferences, the outdoor kitchen feasibility of a house ranks up near the number of bedrooms for our kids in importance! So, if you are thinking about whether to build the over or not, not matter to compromises, build the oven!

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2. My biggest regret by far, was using the only (light duty) firebrick I was able to source at the time. It was a two-hour drive to purchase the brick after talking with sales folks who had little more information than “yep, it’s firebrick, it’s all we stock, and no we don’t know anything about it but it’s price and dimensions”, and no better options were to be found (they were out there, I just didn’t hunt hard enough). To be clear, the light duty nature of the brick’s thermal mass is perfectly acceptable for the needs of my family. It heats up fast, stays hot long enough for high temperature cooking and then retains enough heat for me to slow cook briskets and other meals over the next several days, I had no complaints about that aspect. However, the durability of the brick is terrible. I saw this with fear during the construction process, but it was even more clear after only a few months of use; the chipping and wear marks on the archway and floor of the oven were heartbreaking after putting in so much effort. When we left there were 1/4" groves where the door slid into place and chips all over the archway. The floor was also starting to lightly pit everywhere I cooked. This time around I have sourced (another long distance) medium duty firebrick to use on the archway and floor. I plan to use the same (this time locally available) light-duty firebrick for the dome, which encounters trivial wear and tear and is only 1/3 as costly as the medium duty brick. If I am going to put in all this work and heart, by golly I want the oven to last!

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3. Get the right masonry saw! Probably my biggest compromise after my ignorant brick choice, was using a woefully inadequate cheap table saw-type tile saw for the brick cutting. The blade was so short I had to flip them to finish cuts, and bevels of any sort were a painful and unsatisfactory experience that can only be called embarrassing. I knew it was the wrong choice, but it’s what I had, and the price was right. Like I said earlier, I have no regrets on building it when I did, but I plan to properly source a good (probably used) overhead masonry saw so that I can do all the proper bevels and angles I want without the crushing limitations of a tiny saw.

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4. I’m excited and delighted to prepare to build my next oven with tighter cuts for all the bricks. Thanks to the helpful work of others (like this discussion here), I plan to cut the bricks along both the “tilt” and “side” angle planes, hopefully creating a tight and self-locking brick dome with minimal use of mortar. My rough-and-ready first oven cooks just as well as any oven I’ve heard described here, so this decision isn’t about making better pizza, rather it’s about my wanting showcase my best craftsmanship. These last few years have been rough ones for me, but something I’ve taken from them is that I’m never happy with my rushed, half-ass efforts, when I knew I could do better; and I am excited to do better this time around!

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5. You can never have too much thermal insulation! For my first oven, I mis-calculated how much woven insulation I would need as I was trying to save money, and so the top of my oven had a measly 1” and some scraps to hold in the heat. Like I said, in practice I was still easily holding temps in the 200Fs several days after a firing, but my failure, and the resulting compensation with vermiculite has bugged me as a matter of principle ever since. Mk 2 Oven is getting 3” glorious inches around the entire oven, with carefully thought out insulating around the doorway and the inclusion of a thermal gap like UtahBeehiver describes here.

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6. I’m considering integrating an ash slot into my oven, right in front of, or under, the door jamb, as a combo thermal gap and ease of use feature. Using our oven regularly showed me the wisdom of a slick way to dispose of the ash rather than to rake it all out the front and inevitably all over everything else. I’m thinking a piece of lose stainless steel square tubing to bridge the gap on the oven floor (Like Russell uses in the above link), and a fabricated stainless steel “funnel” with a tray catch hanger I can integrate into my concrete slab pour. One simply would have to place a bucket or tray under the slab, pull out the loose piece of stainless-steel tubing covering the slot, and with a few quick rakes all the fine ash falls down the shoot and is neatly funneled into the bucket. Between my concrete skills (had to pay for college somehow!) and my brother in laws excellent plasma cutting and fabricating shop, I think we can come up with an excellent system to integrate into the build. However, I’d love to hear other’s solutions for an easy clean out system!

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7. Thermocouples! To be clear, a handheld infrared heat gun works just fine and was even fun for the kids and adults alike, but I think it would be nice to have several temperature readouts integrated into the oven. I’m thinking in the center of the floor, on the side, and at the top of the dome. I’m just techy and nerdy enough to want to go digital so I can capture and log the readings, but also pragmatic enough to just want a basic instrument that “just works” with zero hassle.

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8. A beautiful façade and finish for the oven and outdoor space. I never planned on doing anything fancy for our original oven, and it was a simple affair where I made a practical but unremarkable stucco dome for the oven and never minded the bare masonry CMUs for the stand. My wife always wanted it beautified, so this time around there will be more!

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9. A simple steel chimney instead of a brick-built one. This is more of a preference than an absolute. My brick laying skills are not amazing, and I didn’t enjoy the work of the brick chimney I made, I think I’ll go for a nice (easy to install) dura-vent one this time around, but that could change based on how the exterior design and decoration plans go.

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10. So many things were GOOD choices that I don’t regret, and I thought I would mention a few of them here:

• The 42” oven is an ideal size, big enough to run two or three pizzas at a time, I’m glad I went for the bigger one!
• A corner installation makes for an easy and accessible space for serving guests and staging meals with pans and trays such as grilling meats or roasting veggies. Maybe I’d opt for a stone countertop rather than concrete, as the outdoor concrete never feels clean enough to use for bare pizza work.
• Making my own fireclay mortar was easy and relatively fun (kids loved to help mix it) the mortar was strong and worked easier than I expected.
• Building the dome without forms was fun and allowed for better, cleaner work on the insider.

What about others, what are your lessons learned?