2024 Neapolitan oven build

[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.

[Toiletman]

Thanks, that's really clear. You mention you also did some calculation on the strength of it? What kind of calculations did you do? Do you have a professional background in this area?
I watched some online lectures on concrete calculations and reproduced them for my cantilevered slab, as well as doing some exploratory FEM work on what the loads on the brickwork would be. I would assume that any of the typical designs here are way overdimensioned like they should be, and also your ledge won't get any significant loads right? (probably it's own weight is significant). I assume you calculated it to be able to jump on it right?

[daidensacha]

What a wonderful looking build, and great details also in the planning and design considerations you put in. Could you share any details on the rebar in that 'front shelf' you made? It looks quite amazing floating like that.

I cast the shelf at the same time I cast the hearth slab as I reasoned it would be stronger this way. It was actually quite easy to plan the formwork for the shelf as I the concrete cascades back into the slab from the shelf.

I have 5 x 12 mm (1/2“) rebar lengths that go from the back of the slab 40 mm from the top of the slab to the front of the shelf. The 2 outer on each side have 90 degree bends, to account for the difference in height of the shelf to the slab, and are positioned 40 mm from the bottom of the shelf, and have 90 degree bends at the front to connect with the corresponding rebar on the opposite side. I put some 8mm rebar mesh in the shelf, wired to the rebars.

The center rebar is slightly different in that it has 45 degree bends to account for the different height of the shelf, runs from the back of the slab to the front of the self. I figured the combination of the rebars with 90 degree bends and 45 degree bends would add to the strength.

Formwork for the shelf.


Side view sketchup diagram for the shelf and slab with the rebar positioned. Doing this in sketchup was a really good process. Basically wanted the 30 mm granite that will sit on the shelf to sit flush with the floor of the vent landing bricks.



I have 12 mm (1/2“) rebar at 300 mm spacing 40 mmm from the bottom of the slab running front to back, and side to side, wired together. Tied in with the 8 mm vertical that is concreted into the cinder blocks.

Lastly, on each side of the concrete arch under the front of the slab I have 2 vertical 12 mm rebars that also give support to any forward stress.

I left the formwork and props on for just over a week before removing them, and we had a wet week which worked out well for the curing process.

These additional images are to add some clarity to what is explained before. Hope its clear.
This image shows the side view of the rebar that extends from the front of the shelf to the back of the slab. The rebar with a 45 degree bend is positioned center. The second and third have 90 degree bends, and are positioned more to the side of the shelf. On top of these in the shelf, I wired rebar mesh, not that it was really needed by my calculation, but more that I didn‘t want to regret later not adding it.

[Toiletman]

Formwork removed

What a wonderful looking build, and great details also in the planning and design considerations you put in. Could you share any details on the rebar in that 'front shelf' you made? It looks quite amazing floating like that.

[daidensacha]

Formwork removed

I removed the props and boards supporting the oven hearth and also the formwork on the attached countertop.

The conduits I inserted in the hearth concrete for drainage were easy to locate and I‘m holding off drilling out the tops until I‘m ready to start on the dome.

Want to lay a row of bricks on the back of the countertop, and render the whole stand in the coming week before I head of to France for a weeks holiday.

[daidensacha]

david s That link is a good read, thanks David.

The shelf will sit flush with the front of the vent arch, which will be 334 mm plus the width of the decorative arch bricks from where the vent meets the oven opening. There will be a 12 mm heat break in the vent, so the granites exposure will be limited to radiant heat from the oven.

im yet to stand in front of this type of oven at heated temperature, but I’m sure you have plenty of experience with it. In winter here it can be cold, usually min temp somewhere between 0 to -7C. I don’t think ithe granite will reach super hot temperatures, but I guess I’m gonna find out.

[david s]

Granite is well known not to like heat because it is sensitive to thermal shock and therefore not a great choice for a wood fired oven, Not sure how close you plan on it being to the heat source, but the combination of heat from the oven on a cold night could be problematic.

"Thermal shock can be exacerbated if the temperature fluctuation is uneven throughout the material. As a material cools or heats too rapidly, tensile stress between the surface and inner layers develops. Depending on the chemical makeup and bonds of a given material, the tension between layers will force the chemical bonds to break."

Fingers crossed.

https://www.colonialmarble.net/hot-p...%20for%20yours.

[daidensacha]

That is some pretty fancy shelf and hearth concrete work.

I have a nice piece of black granite, “Nero Assoluto”, 1450 x 300 x 30 mm that will sit on the front of the shelf, the second tier is for the decorative arch. Handmade green moss 125 x 125 mm Italian tiles to go around the front of the shelf under the granite. That second tier sits level with the top of the insulation fibre board, and the floor bricks will meet the granite at the front of the arch. Did all the plans in Sketchup, down to the millimeter and knock on wood, it came together perfectly. I’m really happy with the result so far.