39" (100cm) Pompei Oven Build in Belgium

[Kvanbael]

Hi everybody,

I have started my 1m (39") dome pompei oven build. I am a total masonry noob, but we're going for it anyway. Today my stepson an I poured the slab. 25cm (10") thick. So I guess there's no way back now.

Here in Belgium we are in our 3rd week of virus lock-down, so not so easy to find affordable building material. But on the bright side, we have more time at hand than during the usual social rat-race, and we're staying safe.

We'll keep you posted in this thread.

[JRPizza]

Welcome to the forum! I build a 39" oven, so if you have any questions about dimensions etc just let me know or make a post and somebody will likely try to answer. Glad you are staying safe - we are trying to do the same here in Washington State.

[Kvanbael]

Thanks for the offer JR. On paper, I finished this thing already 6 times :-).

I started on the base. I couldn't find open blocks (especially now). So I settled with hollow blocks with are joined with mortar. Aiming to go for 4.5 layers, which will result in a table height of 100 and an oven height of 108cm (42.5")



In case you wonder about the layout, below is an "augmented reality" view of the intended end result. I shortened the wood storage with an extra wall to get more support for the oven.

[Bocktn]

Hi, just starting mine in Tennessee. Will follow you as I am a noob as well and a few clicks behind you in construction. How do you plan to construct your floor? (On top of slab but under fire brick). I am having all kinds of back and forth on what to do there.

[Kvanbael]

I was planning on 5cm (2”) of calcium silicate board. Forum got me worrying about potential water buildup underneath. So I will add some weepholes and some scoring in the slab for draining.

[modified9v]

Best of luck on your build Kvanbael!!! Beautiful back drop. It’s so green.

[Kvanbael]

Thank you for the encouragements. It's very green indeed this time of the year.

An update after a weekend of building:

Saturday was expected to be rainy, so too cumbersome for doing masonry. Instead I cut my last row of base bricks, and made my version of the "indispensable tool" with stuff I had lying around (hardware stores are still closed). I really insist on the hinge point being flush with the oven floor (so that the inner dome height equals the inner radius). I came up with this simple mechanism. I hope that the weight of the brick will hold it in place. It will require one hole in my oven floor, to temporarily hold a nail. The other end is just two pieces of plywood. Aligned with the top half of the brick. The bottom half is tapered so that the tool can be lifted without dislodging the brick (in theory).

Sunday was sunny, so I finished the base and took the afternoon off. The base is 35" tall. Oven floor is expected to be at 43". My L-beams are huge, but you can't be too picky in lockdown times. I'm so glad to proceed to the next phase in the build: Boxing the "heart".

Government announced that DIY stores can open again, so things will be a bit easier from now.

Build album available here: https://www.dropbox.com/sh/wp8aritqn...L-cYpWB_Zi4Zba

[UtahBeehiver]

One key component to the IT aligning the brick correctly is that the pivot point (which are placing at floor level, which is great) along the wood beam intersects at the middle horizontal point on the brick for the dome. This ensures that the brick face is perpendicular to the center point on the dome. If it is not, then the brick face is off and the error becomes cumulative as you move up in courses. It is hard to tell from the pic but it appears that the projected line hits on the bottom of the brick rather than the middle.

[Kvanbael]

Thanks for the advice. I believe that I did take that into account. Bricks are 55mm in height, offset is 27.5mm.

[UtahBeehiver]

Your good then

[Yokosuka dweller]

One potential issue with the nail and bracket approach - it looks like the hole where the nail goes through is elongated and has a bit of travel, so you could risk getting your diameter guide 'out of whack' if that travels too easily. is it possible to replace the bracket with one that has just a round hole in that position, or weld the existing one so there is less travel? And, the hole for the nail --> you can replace the center brick with a wooden brick to easily hammer in that nail, and then replace with the original brick once you're done with the IT.

[Kvanbael]

Many thanks for the words of support and advice so far. Yokosuka dweller, we will indeed have to pay attention with the IT that the nail is always at the end of the slot, the weight of the brick should also help to keep it there.

Another weekend passed, another build update to share.

On Saturday I did the framing for pouring the heart. I couldn't buy any wood, so I was grateful that my brother in law had some leftover coated plywood. It is strengthened and supported by oak beams (2.5x2.5") that used to hold a ceiling.

We plan to poor the heart next Friday or Saturday. So I have to finalise and lift the rebar and add tubes for vent holes in the next days. To avoid spilling, what's the best way to seal the cracks between wood and brick? I could seal them with mortar a day or two before the poor. I could also use masking tape. I could go and buy silicone, but afraid that won't look nice.

And to make sure the wood will come off easily, what's a good oil to use? Bake-Easy spray, WD-40 spray, olive oil, ... ?

[Yokosuka dweller]

Looking good so far, make sure you have more than enough vertical support beams for the form, concrete spill would be a disaster. And I just used duct tape to seal any big gaps, but small gaps actually were not a problem and no concrete really ran through - of course depends on how dry/wet you mix your concrete. And I used olive oil for the wood, although my wife later didn't appreciate I had used her extra virgin olive oil for that...

[Kvanbael]

Weekly update, and again some questions.

Over here we celebrate labour-day by... well... not having to work. So friday was scheduled for pouring the heart, despite the rain forecast. So, underneath some cover, and in between the showers, we got it done, except that we ran short on concrete and so we had to level it by eye a fraction underneath the frame border. (it's still over 3,5" thick)


I also installed 4 weep holes and plan to put glass mosaic leftovers under the insulation to keep it dry and help to channel any seep-in water.


On sunday I jigsawed the Calcium Silicate board, which was an easy but dusty job. (As you can see, I'm not laying the vent floor right now. I intent to lay that floor separately, making minimal contact with the oven floor to limit heat loss when the oven door is closed).




But, when trying out the Calcium Silicate boards, it became obvious that the heart isn't perfectly flat: There's about 2mm (1/10") variation in its height, and that makes the insulation boards a bit wobbly (Luckily most of the weep holes are in low areas). I am afraid that the boards will crack as the load increases. Should I...

• Not worry about this, let the board "set" under the load ?
• Use fine sand under the mosaic to level things ? (I have fine white quartz sand, but won't that erode eventually through the weep holes?)
• Remove the mosaic tiles at the highest spots until the wobbling stops?
• Try to sand the highest spots in the concrete?
• Any other advice?

I'm also wondering how long I should wait before removing the supports from underneath the heart.

[Yokosuka dweller]

Looking good so far. People on here have often used a dry mix of sand and/or fine fireclay to level on the hearth. Also can be a good idea to glue a fine net/mesh onto the weep holes so nothing can crawl up from below and start eating away the silicate board. I didn't use silicate board myself so don't know if it would settle naturally by the sheer weight of the oven, others with experience might be able to tell you. I pulled my concrete forms around the hearth after about 1 week, but let the supports stay for around 1 month, since they didn't interfere with the build anyway.