36" build in heart of Europe, Czech Republic

[mrotter]

Hello guys.

I am beginner, did not do any brickwork/masonry before, but love to bake pizza and bread. Just started the work on my WFO in our backyard.

The oven should be around 90-100 cm internal diameter, dome design of course. Underlying hearth/counter/slab will have dimensions around 140x160 centimeters.

[mrotter]

I am about to pour hearth under the oven. I plan to use standard home-mixed concrete (same as for base), it will be around 10-12 cm think, concrete surface will be polished with sandpaper (only visible parts).

I am following Forno Bravo WFO PDF along with some videos.

Any constructive input is greatly appreaciated, thank you fellaz.

[david s]

The Ancient Roman’s used slaves pushing large stones to create their terrazzo floors. If you have a plentiful supply of slaves it’ll work ok, otherwise it will be a LOT of effort. Wet and dry sandpaper in progressively finer grades and some water is the usual method, but you might prefer to buy or hire a dedicated polishing machine. I use one which is basically a large variable speed angle grinder, with a decent electrical cutout switch and a central water feed in the main axle. They come with diamond pads in varying grades that attach to a Velcro head. After 3 or 4 hours of hand sanding you’ll probably decide to use one.

[mrotter]

I actually bought some concrete "polishing" diamond discs/pads to angle grinder (with variable RPM which i own). If they work, I will use them and not sandpaper ones of course.

[Ethan1989]

The work is very good it's looking like professional MASON had done this. I had one question Are you using marble titles after cement floor or using another stuff?

[mrotter]

The work is very good it's looking like professional MASON had done this. I had one question Are you using marble titles after cement floor or using another stuff?

Marble tiles where? On the ground inside? I do not plan to use any tiles. Just preparing framing to pour slab under the oven tomorrow.

[mrotter]

Poured hearth concrete slab. I plan to continue in spring next year, as temperatures are about to drop to zero soon. Will polish concrete in the weekend.

[mrotter]

Guys, I would like to ask about under-floor insulation thickness. I will buy Ca-Si boards as they are relatively affordable here. Is 5 cm (2") good thickness or should I definitely go to 6-8-10 cm or is it a waste?

[UtahBeehiver]

2" is the "minimum" recommended thickness but it also depends on how you plan to use your oven, ie pizza party, multiday cooking, baking etc. Before you buy CaSi, you should post the specs on the blog for review, not all CaSi boards are suitable, especially compression value but also post K value.

[mrotter]

I see.

Intended purpose: small batches of pizza (usually much less than 10 pizza, around 5, 1-2 loaves of bread, some long-time slow baking of salt or sweet dishes). No really big parties, no multi-day cooking.

I just aim to have "standard" insulation. I managed to buy shitloads of Fiberfrax blankets (to cover dome) almost for free so dome will have more than adequate insulation.

Well the exact board I have chosen has these params:

Not sure what "compression value" is when translated to Czech but specs say 2.8 MPa (that is 280 000 Kg per square meter) which I believe to be more than adequate value, also not sure what "K" value is.

Specs attached.

[UtahBeehiver]

2" is probably good based on your cooking "current" criteria, that said, if the CaSi is inexpensive in your area, an extra 25mm will make the oven much more effective for future mullti-day cooking. You can add now but never later. Compression value is good, K is Thermal Conductivity and the values are right in line for CaSi used for WFOs.

[mrotter]

2" is probably good based on your cooking "current" criteria, that said, if the CaSi is inexpensive in your area, an extra 25mm will make the oven much more effective for future mullti-day cooking. You can add now but never later. Compression value is good, K is Thermal Conductivity and the values are right in line for CaSi used for WFOs.

Thanks, OK. I polished the concrete base and will continue in the spring. OK, I will aim to 60-75 mm CaSi thickness. Thanks.

[mrotter]

Polished concrete a bit, filled some minor holes.

About to order 70 mm CaSi boards (along with other materials needed) to build the actual oven.

Continuing in spring.

[UtahBeehiver]

Keep the CaSi in a dry area, it is really water absorbent. When you start next Spring, look at blog to see how builders keep the CaSi from getting wet when laid. Do you have any weep wholes in the concrete hearth, if not now is the time to drill some in while the concrete is green.

[mrotter]

Keep the CaSi in a dry area, it is really water absorbent. When you start next Spring, look at blog to see how builders keep the CaSi from getting wet when laid. Do you have any weep wholes in the concrete hearth, if not now is the time to drill some in while the concrete is green.

I see. Never really thought about weep holes as I would really like to avoid getting water sucked in in the first place. Weep holes seem reasonable to do. Do I need to have 'river' ways between concrente heart and CaSi to allow water 'flow' into holes? I see at the other thread that someone placed CaSi on layer of semi-crushed ceramic tiles.