Homebrew castable build, Newcastle UK

[mesoiam]

Yeah that's two sheets of 1000x500x50mm calcium silicate. The corner offcuts are triangular and reused to extend the front portion to make the whole thing keyhole shaped, under that is about 50mm of 5:1vcrete.

[mesoiam]

What do you have between these layers? Are these layers attached to each other with any type of mortar? Please explain! Thank you very much!

There's nothing between them, it's just a sandwich. I used a sprinkle of fireclay to level a few of the bricks, some people do a whole layer of sand to lay the bricks on but I didn't as the board was already pretty flat. I don't think any kind of adhesive is necessary because this is so heavy friction will keep it from moving.

[mesoiam]

It is going to take several weeks to dry and even consider any type of cure fire.

Thanks, I knew there would be a long wait. It's currently residing under a damp sheet, how long would you recommend for damp curing before I demould and let it air?

[sergetania]

Thank you for responding! Pretty amazing. Building an oven will be weird. I will have to fight a desire I always have to fasten everything. Nothing at all on all layers, not even under firebricks that hold the dome!? Ok, I will try!
I will be following the rest of the build with lots of interest. I want to see how you attach a gallery to the dome and build a chimney. Please continue posting detailed pictures! Best of luck!
Cheers!

[mesoiam]

This is my first oven so I'm still learning things, the build is based on previous builds by DavidS, worth checking out those builds that are tried and tested.

[sergetania]

Definitely, still reading the forums. Yours was at the top and nicely illustrated. Thanks!

[mesoiam]

So yesterday I got the flue gallery cast. I made wooden insert with bevelled edges which will be a kind of inverted funnel when it is removed. Attached to this is the chimney with a removablelayer of cardboard around which will leave me with a small expansion gap to prevent the possibility of the expanding steel breaking the casting. I added a bit of blue foam edge strip to make the gallery diameter larger than the inner entrance (white curved board), this will form the stepped surface that the door sits against.
I made a semicircle of chipboard and added some wooden 'spokes' again using curved hardboard to form the radius.
Built it up with wet sand and bits of brick and made up the same homebrew mix.
There is a double layer of cardboard separating the dome and gallery castings, later I will remove this carboard and fill with some vcrete. I was worried about the freestanding gallery toppling over someday so I linked the two parts with a bit of bent coathanger wire like large staples just in case.
All wrapped up in wet blankets for damp curing.

Some second thoughts: I think I should have taken a bit longer to invent a way to step the chimney back further, then the gallery could be less deep. The casting goes almost all the way to the front of my concrete hearth at the moment without insulation, because I didn't want to leave the outer doorway too thin and fragile. I'm still undecided how to finish this part, I might anchor some big bolts and cast a shallow shelf onto the existing concrete to provide a footing for a decorative arch, or maybe this part can just stick out a bit if i render the whole lot and curve it out starting from the bottom of the concrete. I have already left the concrete slightly shy of the red brick, thinking that I'll cover the whole lot with mosaic tiles or something. Ideas welcome!

[sergetania]

Inspirational! Lovely job!
If you don't mind a couple of questions. Is there a picture missing where the gap with bricks is filled with sand to form the gallery? There are two yellowish structures - the arch and something that the chimney sits on. Are these the actual arch and firebrick chimney foundation that will stay within the cast when all done? Also, the brown paper separator between the gallery and the dome - that's going to come out. What's going to fill that gap? Thanks a lot! Oh, how is the metal chimney base attached to the brick foundation (if the are bricks). That is it for now! Sorry about the questions, I could have searched the forum for previous builds but it is hard not to ask, this build is awesome (and this is the most sincere flattery :-) )!

And how are you dealing withe wait before you can remove all that stuff around the cast!?!?!

[mesoiam]

Thanks, Yes I'm afraid I didn't get a picture of the mould before applying the homebrew. The hollows were filled with damp sand up to meet flush with the bottom edge of that yellow wood that is holding the chimney. The whole thing will just be an arch shape that curves into a funnel to meet the chimney. Everything will be removed leaving only the cast shape. There will then be a hole on the top thats slightly larger than the chimney, I will cut some slits in the chimney and bend them out to produce holding tabs that will stop the chimney falling right through and vcrete it into place. The cardboard spacer will be removed and filled with vcrete so that the two different casts can expand and contract independently hopefully without cracking. The only bricks involved are the floor firebricks, any red brick you see is just for mould filler and will be removed.

[sergetania]

Got it! Thanks! The yellow parts are under the concrete to form the arch and the vent ceiling.
The firebreaks is another new concept for me. I see other builds where the gallery is cast completely separate from the dome. Since the vcrete used to patch the gap doesn't really glue the two parts together I am assuming they just stand next to each other, unattached. The vcrete patch simply covers the gap somewhat. It's a crashable zone that does not even seal the gap. Could you use a fireproof rope in the gap instead? Is a separately-cast gallery even cemented to the firebrick floor or it just literally stands next to the dome? Trying to understand, thanks for the patience!

[mesoiam]

It's cast right on top of the firebrick, it probably does stick to it, as I mentioned I put some wire ties into it as a safety measure, but the whole thing will be covered in fireblanket, vcrete and a render shell so I'm hoping that will help keep it together. Have you found the previous builds by DavidS? He even has a cutaway one, I'm replying on mobile and it's a pain to search but it should be easy enough to find. I really must stress that this is my first build so reader beware!

[sergetania]

Yes, I saw you mentioned the Longmont build and I am in the process of reading that thread. Super informative. That's the build where the gallery was cast separately which in my eyes made it easier. I hope that oven still stands!
This is your first build but it's apparent that you have learned well. I have seen you asking questions so that makes me hope you may answer some of mine. I am very thankful for that!

[mesoiam]

No problem

[hughjamton]

Just a quick question, did you use sharp sand for the mound and the homebrew?

[WoodywWun]

Hello mesoiam. Looks like you have done some good research and got some great advice. Have you taken the next steps in your build?