2024 Neapolitan oven build

[daidensacha]

Levelling hearth floor bricks on calcium silicate board.

I’m about to layout my floor bricks to mark for cutting, and anticipate I’ll need to use something under them to level them.

In Germany I’m having trouble working out the equivalent material for fireclay. Schamottemörtel is available, which I think is probably it. Fire resistant mortar made from powder from the fire bricks. I read that using a 50/50 mix with sand, then troweling it as when laying tiles is suggested.

It maybe a silly question, but I don‘t want to use it wet on the calcium silicate boards, so can I use it dry?

Secondly, I read that some have used only sand without fireclay. Would this be ok?

[daidensacha]

For clarity, I wasn't advocating to change the arc of the dome, it would would just move up or down with the height of the vertical courses.

BTW, really admire your casting and concrete work.

Thanks Giovanni.

I have some skills with my hands, and learnt lots doing renovations in a few houses in my life. That said, transferring that knowledge and applying it to this project does require a considerable degree of problem solving. I’ve enjoyed it so far, and as hard as it has been on the old body, the physical exercise has been beneficial. My long term back pain has virtually disappeared, like a miracle.

Still lots to do, so I’m focussing on what’s coming and enjoying looking in the rear vision mirror at the result so far. Cut the calcium silicate sheets today, and lots planned this next week to prepare for starting on the dome.

[Giovanni Rossi]

For clarity, I wasn't advocating to change the arc of the dome, it would would just move up or down with the height of the vertical courses.

I get your thinking, though I'm not sure the height differential is all that significant. My oven is similar to your plan at 1067mm ID. I just eyeballed it and, at that size, the first courses of the Pompeii style dome are not far from vertical and give plenty of height at the edge to maximize usable floor space. The only time I really use all of that space is when I bake large batches of bread. When I do that, I have to manage the bake more because the radiant heat from the dome bakes the loaves faster on the sides in close proximity. I find if I bake less and leave a buffer from the walls, I get a much more uniform bake. I'll bet the Neapolitan design would mitigate that problem with dome being lower and providing more uniform heat all around the loaves.

After I sent the reply yesterday, I was thinking about the variance in height and how to fix that. We have fire brick splits here that are used to line fireplaces. They would be 230 x 114 x 32 mm.
Using one course of those and 3 courses of standard with thin mortar joints would pretty much match the height of a soldier course.

Good luck no matter which way you go!

BTW, really admire your casting and concrete work.

[daidensacha]

Giovanni Rossi

Interesting, I’ve been planning my Neapolitan oven for some time, and it wont be limited to pizza, will definitely cook bread and meat in it too.

I was planning on the full soldier course. The refractory bricks I’m using are 230 x 114 x 64 mm. I considered at one point laying courses as you describe, but 4 courses would take the side higher than the soldier course, and then call for a much flatter dome which I didn’t want. Alternatively I could have made the initial straight sides lower but I didn’t want that either. So I’m staying with soldiers, but considering David’s idea to make two half height bricks as described.

[Giovanni Rossi]

I'm glad david s posted about this. I've read a ton about soldier courses on this forum and there's certainly a myriad of opinions. Before I decided to go with the pre-cut kit, I was trying to decide between a Pompeii style and Neapolitan style build. Ultimately, I knew I was going to bake/cook things other than pizza probably 75% of the time, so the Pompeii style kit worked fine for me.

daidensacha looks like you've modeled David's idea with the bricks oriented with the 2.5" dimension left to right.

I was clear on the need for vertical sides before beginning the arc the dome to achieve the Neapolitan style oven. However, I never understood why that was accomplished using a soldier course. It made sense to me to just lay 3-4 courses of half bricks flat to start. That allows for proper joint staggering that could just be continued on subsequent courses. The dimensions would be similar, ~7.5" - 10" of vertical rise and 4.5" of thickness before the dome. But, I would think that configuration would be more stable. Maybe buttressing or a steel strap would still be needed, but it just seems the better way to go. If the novice has missed something here, I hope others will point out any error in my thinking.

[daidensacha]

A steel strap to support the bottom bricks is the method used by the Neopolitan ovens. The difficulty is anchoring the ends of the strap so that it doesn’t impede the entry.

Yes, I did this deep dive earlier. I have my brackets and stainless steel straps in the garage. Plan to make up a frame over in similar way to that implemented in Napolitian style 106cm build inside a hobbit house.

I was still unsure if the straps would be sufficient to reinforce the soldier course sitting directly on the calcium silicate sheets.

[david s]

A steel strap to support the bottom bricks is the method used by the Neopolitan ovens. The difficulty is anchoring the ends of the strap so that it doesn’t impede the entry.

[daidensacha]

david s

Thanks for your input David. I appreciate it a lot. I understand there will be many different opinions, and it really depends on the particular application as to what fits best. I‘m one to weigh up the info at hand and given I will live with the consequence, make the decision I think best for what I am doing.



I knocked up this image in Sketchup. I gather this illustrates what your preference would be, to have two courses of half bricks atop each other in place of one course of full height soldiers. I can understand it would add additional strength, while giving the required height before beginning the curve of the dome.

Cutting the bricks in half is easy with the wet cutting saw. It’s worth consideration. I‘m in accordance with your advice on placing the first course directly on the calcium silicate sheets. It was worrying me doing this with full height soldiers, so your alternative per the above image is a good one.

I still have 2 stainless steel straps with tightening bolts to attach to the front arch to prevent the bottom course blowing out.

[david s]

With no expansion joints in the dome there’s probably no difference in placing the first course directly on the insulation or on a mortar bed. Provided the insulating board is flat, mortar or a dry levelling medium shouldn’t be required. Because the board is so water absorbent applying mortar to it presents problems. Although, if it were mine I’d be placing the first course directly on the board.

I’m not a fan of soldiers (placing the bricks on end) because it results in a long joint between each brick. The base of the dome is the weakest part of a hemisphere and usually where cracks originate. The reason bricks are staggered is to eliminate coinciding vertical joints. Placing bricks on end is like coinciding vertical joints. I think if you want the height a vertical soldier course produces you’d be better off laying the first two courses with half bricks, staggered vertical joints, laid flat and vertical, with subsequent courses following the arc of your desired radius.
I’ve been reluctant to reply to this post because others will no doubt disagree, but it is a question worthy of discussion.

[daidensacha]

First course of oven dome

I could use some clarification on the laying the first course from someone who knows about it.

I plan to lay the first course of soldier bricks directly on 100mm thick ceramic fibre sheets. I have zero experience with the ceramic fibre insulation, but understand from reading that getting it wet can undermine its integrity. I also read different opinions on whether to cement the first course or not to cement it. Some use a mix of sand and clay, some use nothing and say the weight of the oven will be sufficient to secure it to the base.

I do also have stainless steel straps that will be wrapped around the first course to reinforce it.

Question: Is it viable to use no sand or cement at all under the first soldier course, only using refractory cement between them to secure them?

I had planned on cutting oven floor bricks to fit inside the soldier course, leaning aprox‘ 5mm gap to allow for expansion.

[daidensacha]

Construction moving forward.

I received approval for our terrace construction this last week, so I was able to order timber which will take a few weeks before it is delivered. Also ordering sandwich panel sheeting for the roof.

I finished rendering the base and gave it a lick of paint before laying the paving. It will get another coat once I have finished the dome.

I was able to lay 4 pallets of paving last week, but was 3m² short of pavers. The extra pavers also come from the factory so that will be next week before I am able to finish the paving and put that job behind me. Overall happy with the job so far. Once I lay the final pavers I will run a compactor with rubber mat over them to set them and even the surface.



Given the expected time frame for completing the terrace roof now, with first frost due in mid October, I‘m re-assessing my plans and am considering starting the dome in the next weeks. Means I‘ll need to keep a tarp nearby and ready to keep it covered and protected from rain.

[UtahBeehiver]

Nice looking doors

[daidensacha]

Finished rendering the oven stand at last

It’s been a really wet start to summer this year in Bavaria. When it rains it really pours, and it’s been really unpredictable. It’s been a bit hard getting a run at rendering oven stand, but today I finally managed to finish it. I’m going for a rustic theme with the finish, so visible washed out trowel marks are visible. I added a smooth skirting around the bottom that I will paint to match the okra color of the pavers.

Going with the rustic theme, I added 3 courses of recycled hand made historical red bricks on back of the work bench. I want to use the same bricks for the decorative arch and possibly to add character when building up the chimney.

I’m elated the oven stand is done at last, that was heavy work, and required learning new skills to get it done. It was worth it though.

[daidensacha]

Oak Doors for wood storage under oven

I’ve been looking for some old oak beams I could recycle and use to make a set of doors for the wood storage under the oven. A friend had some rough cut oak in his attic for the last 10 years, and he offered it to me. Of course I said yes, gratefully.



I took it down to a local sawmill to put through a plainer. It needed some straightening. Also made use of the good machinery there to cut it down to size.



Then yesterday in my workshop I did the mortise and tenons, cut center panels out of left over oak floorboards and glued it all together.



It was a little tricky cutting the tops to fit the arch under the oven landing. Put the doors inside and traced the shape of the arch onto the tops, then little by little I removed the top of the doors until I was happy with the fit.



38 mm thick doors, nice and solid. I’m just making up some oak beading to go around the inner panel. They are sanded, so once the beading is fitted I can oil them and fit the hinges. They’ll then go back in my workshop until I have the terrrace roof on.

I’ve been working on the render of the oven stand, and it’s been taking much longer than expected as the weather here in Bavaria has been really wet this summer. Good news though, today I managed to get it finished, so I can move on with the paving now.

[daidensacha]

Toiletman I’m not a professional, only a life of experience doing all sorts of things. I worked a bit with concrete, but not a lot.

With regards to the calculations, I didn’t go to your lengths. But I have a few friends here, one retired builder (he said its bomb proof), another studying to be a building project manager (with a father who is a builder). I spoke with them both separately, and was assured by them it would be strong enough. I was told that 8 mm rebar is standard here in such applications, and would have been plenty strong enough. Using 12 mm was what I had at hand, so I used it, and it really took effort to bend it up using a vice and a piece of water pipe.

Casting the hearth slab and landing at the same time was a no brainer, as the strength of one piece of concrete will increase as it cures. Together with the added tensile strength of the rebar, I don’t see it cracking or breaking.

The landing weight calculated at 2700 kg per m³ for dry concrete.
1. Forward of the front of the oven (1350 x 250 x 125mm) is 113 kg. (149 kg with granite fitted, not substantial in my view given the rebar added)
2. Part sitting over the hearth slab (1350 x 114 x 105mm) is 43 kg.

Granite Assoluto Nero at density 2700 kg m³
Size: 1480 x 300 x 30 mm - 36 kg

The decorative arch will sit on top of the back part of the landing, joined to the vent arch with cement. I hadn’t planned on this being a source of reinforcement, but it will add weight to the rear of the landing reducing any forward stresses. I’m counting on the tensile strength of the rebar preventing any cracking. When I come to build the dome it will be well cured, and I will give it a test. I’m around 80 kg, so at some point i’ll post an image of me standing on it. In normal use, it will only have some pizzas sitting on it, maybe a tray of meat, or an elbow and a beer or two. No plans for heavy loads at all.

This build is one I am enjoying, and a process I am breaking up into chucks as I am working simultaneously on 2 other projects that fit with it. The 45 m² terrace with a roof which will house the oven, and a balcony extension with staircase that leads us down to the rear terrace and back garden. RIght now I am working on the render of the stand, and then onto the paving of the terrace, followed then by the terrace and roof. Here in Bavaria with the inclement weather I’m holding off starting on the oven dome until it is covered by the terrace roof. Then I can enjoy the dome build without worrying about being caught by a downpour that my floor insulation will soak up. Once the terrace is up I expect the build to go much faster.