MakaDemian 37" Brick Oven Build with round base in BS. AS.

[david s]

At 220kg/m3, the density of that board is similar to calcium silicate board and should be quite suitable. If it is less water absorbant than calcium silicate then that's a bonus. If you don't know where the steel reinforcing is then just drill a small diameter hole first. If you do hit reinforcing it should then tell you where the rest of it is located.

If you are using tiles then they need to go under the insulation, not on top of the sand/clay levelling layer. Check my drawing on post #10

How much your oven will be affected by weather depends a lot on your climate. If rainfall and humidity are very high this moisture can build up and create problems, When the oven is first built the moisture content is also very high and assistance in its removal is important.

[MakaDemian]

This is ceramic/mosaic (i really dont know) tiles sheet in 300x300x6 mm each. To be able to cover almost all my slab i need like 16 sheets, it will cost me more than four 2" FCBs
So you tell me that if i put these ones upside down on the slab they are gonna support all the weight ? How do i get a circunsference of tiles ? I dont see how to cut them to the shape.

[MakaDemian]

If you are using tiles then they need to go under the insulation, not on top of the sand/clay levelling layer. Check my drawing on post #10

Hey David, what tiles do you mean ? Refractory tiles (oven floor) or the mosaic tiles to avoid water? The tiles I drew are the ones that goes in the oven floor.
My draw doesn't have ceramic tiles under the perlcrete coz according to SlabSprings "Sable Springs says: " Also want to stress the recommended layers: hearth (concrete supporting slab) with 4-5 weep holes, porcelain/glass (mosaic tile square sheets) laid backing side up, garden cloth (if not using tile squares)," (I think he deleted his post, i dont know why. anyways..). Thats why i thought I could replace the ceramic tiles for only a garden cloth under the perlcrete.

[MakaDemian]

I'm not sure what more we can say. Providing a path for moisture expulsion is a reasonable addition; but your oven will function without it. Again, the importance depends on the environment in which your oven will reside.

If you take the time to research the Forum you will find builders who live in tropical locations and have offered their take on moisture infiltration.

If you take the time to research the Forum you will find many examples of the type of ceramic tile being used. Properly fired tiles should easily support the distributed weight of the oven. If David S is still following this thread maybe he can offer better direction and put your mind at ease.

If you take the time to research the Forum you will find a lot of information about moisture penetrating pericrete.

If you take the time to research the Forum you will find examples of techniques to build weep holes into your plan before you pour the concrete slab. Or, you could just measure and record some locations in your rebar grid so you know where to drill.

I'm going to move to the sidelines and enjoy following your build. Buena suerte con tu trabajo!

Its ok bro!
I said before the materials that i could get around here are not the same as yours, so its useless to see overseas materials if the materials i could get doesnt have the same specs. Every ceramic shop i asked about this kind of usage they told me im crazy, they dont assure me it will support the weight....I suppose they dont have a clue.


nice job, so how did you managed to do a circumferential cut on the tiles ? Not only do I not have the skills to make those types of cuts, but I also won't get anyone to do it.



About the weep holes i liked this idea with PVC tubes (I think). The idea would be after the slab dry to cut it off and leave the rest of pvc inside the slab ?

[david s]

**Refer back to my drawing on post #10

My apologies if you are confused about the fire brick floor tiles. As they are often thinner than fire bricks for the dome they are often referred to as firebrick floor tiles (usually around 50mm thick) not to be confused with the ceramic tiles under the floor insulation.
The ceramic tiles between the floor insulation and the concrete supporting slab should not cover the weep holes. You can easily remove the ceramic tiles that cover them. In fact if it were mine I'd pull out every second tile.

The white fire bricks you referred to are probably insulating fire bricks (full of air) and an alternative insulating material although quite expensive.

[rsandler]

For cutting the sheets of ceramic mosaic tiles in my second oven (my first was built before that innovation was popularized), I just took a brick chisel and banged on them with a hammer to crack them along whatever line I wanted cut, then snipped the mesh with scissors if necessary. They don't need to look pretty and the cuts don't need to be smooth. In practice I left the sheets square until after I placed my insulation and my firebrick floor, and roughly trimmed the insulation, then cracked off the tiles wherever they peeked out from underneath the insulation.

As far as weight, keep in mind that although a brick oven is very heavy overall, the weight is pretty spread out. After all, CalSil/CF floor insulation, or even vermicrete/perlcrete, is much more crushable than a ceramic or glass tile, and the insulation can definitely hold up an oven. I did a calculation on some other post here that the typical pres on the floor insulation comes to about 2-3 PSI (not sure what the metric equivalent is).

On the weep holes, I learned to my dismay that it's not a good idea to have them poking up from the surface of the concrete--makes it really hard to level your slab. Instead, best idea seems to be to plug them with something (I think polyester fibers were suggested, I bet balls of crumpled paper would do the trick), and cut the pipes to sit maybe half an inch below the surface of the concrete. Then you can use a rod (e.g. spare piece of rebar) and a hammer to pop the caps off from the underside after the concrete has cured. But either way, you can leave the rest of the PVC in the slab (indeed, I think you'd have a hard time getting them out!).

[MakaDemian]

**Refer back to my drawing on post #10

My apologies if you are confused about the fire brick floor tiles. As they are often thinner than fire bricks for the dome they are often referred to as firebrick floor tiles (usually around 50mm thick) not to be confused with the ceramic tiles under the floor insulation.
The ceramic tiles between the floor insulation and the concrete supporting slab should not cover the weep holes. You can easily remove the ceramic tiles that cover them. In fact if it were mine I'd pull out every second tile.

Yeah, but i was wondering how to leave a big gap (removing a single tile leaves you at least 1" gap) in every weep hole if then you are pouring perlcrete ? is the garden cloth gonna cover that? mmm... i dont know. If you leave a big gap for the weep hole the perlcrete may plug up the hole.

[MakaDemian]

Ok, finally I'm gonna make three or four weep holes in the slab. I hired other more experienced people to do the job. They are gonna make a small slope on the slab (5mm) and they are gonna put stainless steel tubes/pipes in the lower height of the slab so the water can flow to them (i dont want to leave the weep hole with just nothing inside of it).

I could get this stainless steel tube, its 13.7mm overall diameter with a 1.65mm thickness (yeah i know its too much but had good price). They are going to brace them firmly before pouring the concrete.



I was thinking to make a tiny modification to the slab like this:



So, what do you think ?

[MakaDemian]

I've watched some videos where they compare ceramic tiles vs porcelain tiles:

I think porcelain is the way to go, right ?

So, i found this porcelain tiles in my region, The box comes with 16 sheets of 12"x12" (cover up to 1.64m2)

Is this ok for the job ?

[rsandler]

Yes, those should work. A couple options to make sure they don't block the weep hole. Ideally, you could try peeling a tile from the middle of a sheet off the mesh, such that the mesh stays intact and you have a 1" x 1" gap in the tiles (the mesh will keep the perlcrete from blocking the hole). Alternately, with tiles that small, it's probably sufficient to make sure one of the gaps between tiles goes over the weep hole. You can also try to have the weep hole between sheets of tile, so that you can give it a slightly bigger gap (though not too big or the perlcrete will get in there).

[MakaDemian]

You know Rsandler all this perlcrete pouring with porcelain tiles under it makes me re-think about insulation material to choose from, i know that maybe i could use some kind of garden cloth to cover the tiles so the perlcrete doesnt block the holes as SableSprings told me and i also could do something with the tiles to cut some of them a lil bit to leave the 1" weep holes free, but i also know that if I use for instance Ceramic fiber boards (300 kg/m2 density) It could save me some work and some problems. Unfortunately I cannot get Calsil boards around here.

The issues here are basically two: One, Im not a constructor and I dont even have experience in ovens so I depend on some other people that could do the job, but second all this "experienced" people i could hire that builds wood fired ovens in my country dont have the experience to work with this kind of materials for floor insulation (Although they use ceramic fiber blankets for dome insulation).

So, I still wonder, coz I coundnt find threads in the forum, for how to mortar the first line of firebricks to ceramic fiber boards in case i decide to use this insulation floor material. I get the sensation that those CFBs are too soft to hold a whole firebrick oven, i dont know...

Anyone have some pics, videos, or link threads that have built the oven this way using CFB and building the oven on top of it?

PS: I wanna get clear that im gonna go with the recomendation of this forum for water proof with weep holes and porcelain tiles coz i know now that those porcelain tiles are strong like shit and will hold all this up with no problem, so now im moving to the other step that would be choosing what floor material insulation would be the best in replacement of the perlcrete.

[MakaDemian]

I was thinking besides weep holes and porcelain tiles on the slab, what about covering the whole Insulating boards (calsil or cfb) with aluminum foil ? i mean at least they will never be moistered or wet, right ?
The CFB spec sheets says that if they are moistered or wet when they dry then they recover their insulation properties.

[rsandler]

The problem with aluminum foil is that while it keeps water out, it also keeps water in. Unless you somehow manage to have everything hermetically sealed, some moisture will get in, from humidity in the air if nothing else. Most of the insulation we use for ovens insulates poorly when wet, and recovers when dry; best we can do is try to keep it dry most of the time, and give it a way to dry out when it gets wet.

[MakaDemian]

The problem with aluminum foil is that while it keeps water out, it also keeps water in. Unless you somehow manage to have everything hermetically sealed, some moisture will get in, from humidity in the air if nothing else. Most of the insulation we use for ovens insulates poorly when wet, and recovers when dry; best we can do is try to keep it dry most of the time, and give it a way to dry out when it gets wet.

Yes of course if you completely seal the insulation boards with aluminum foil they will never get wet but the humidity or even water couldn't drain down, but that's the question... what else could be wet that would be worst than having wet insulation boards ?... firebricks ? i think with a couple of wood fires it could dry easily, right?

[david s]

Although some builders recommend the use of foil I believe it is not a good material to use, apart from its difficulty in sealing edges and overlaps, it punctures very easily. You could end up with a small hole on installation, but be unaware of it. Over time with thermal expansion and contraction cycling, perhaps movement could wear holes through the foil. If also using it to reflect some radiant heat, its high conductivity makes it useless if in contact with another conductive material. I think it’s better to give the insulation some space to allow it to breathe. The gaps between the tiles and the weep holes provide this and work well, removing moisture far faster than if everything is sealed up.