Finally decided on 32in castable dome

[david s]

Yes the arch is only mortared at the base, but if you look closely there are wire ties cast into the arch which tie into the outer rendering so the sides and top of the arch become an integral part of the outer shell. Note the wire, cable tie and cardboard spacing to hold the top of the arch in place securely until the outer render takes over. The arch is cast in two layers, a strength layer and an insulating one and also contains 6 mm steel bar reinforcing as well as random fibres. (I'm giving away all my secrets here)

[Mullster]

DavidS thank you for sharing so much! So did your final rendering cover not only the dome and flue section but also bridged over the expansion gap and across your decorative arch? I guess that’s what’s confusing me - if things can expand don’t they expand into that gap and still cause the render to crack potentially?

[david s]

No, because the ceramic fibre blanket and th weak 10:1 vermicrete that covers it have enough give to take up the expansion. We’re talking about 5 mm of expansion@ 400C.

Another issue that should be guarded against is that of moisture expanding into steam. Because one litre of water can expand to 1550 litres of steam there can be a lot of pressure built up in the insulation space. It it prudent to install some kind of vent to both allow pressure release and for faster water elimination. We live in the tropics and ovens here can get wet insulation even if it hasn’t rained for a couple of weeks if the humidity is around 90% Refractory materials will draw moisture from the air.

[Mullster]

How important is it to have a complete top layer on the stand (as per the FB plans)?
im thinking to use an E shape stand giving me two more accessible storage areas on the side and I can make it without even cutting a block if I build without the top layer being a complete one. With a 32in castable dome doing on top (not brick) I’m wondering if this will be plenty strong enough anyway?

by complete I mean bridging the openings with angle iron etc

[Mullster]

aaronpizza a tip based on today’s experience of dry building the stand and trying to figure out the right pattern - try to avoid the 440 x 215 x 100 blocks rather than the 440 x 215 x 215 - I’m finding the options for config are much harder than if the blocks where half the length for the depth.

[UtahBeehiver]

I am a little concerned about a dry stack with solid core blocks. With hollow core, the cores are filled with concrete and rebar for lateral strength.

[Mullster]

UtahBeehiver dont worry - the dry stacking was purely to figure things out - going to mortar the whole thing.

Today was a weird one - started with a foundation only and ended with a foundation only - which sounds discouraging but actually I’m completely set for tomorrow and cementing my stand together.

Despite having made some scale plans I found I spent several hours today trying out different configurations for the stand - dry stacking, taking apart and dry stacking again. Must have lifted 40+ blocks at least 3 times each so definitely feeling it now. The beer is calling!

I was anxious about cutting block which I think was hindering my designs. I used an angle grinder for the first time today and it went really well! I was able to cleanly cut 4 blocks in the end and I have a design I like with two side storage chambers (an E shape).

Feel like I’ve learnt a lot today and tomorrow will be my first time cementing so that should be interesting!

Finished by numbering the blocks so I know where they belong and then dismantling again!

Added some pics from the day.

[JRPizza]

I didn't use any angle iron under my hearth as I didn't think it added any additional strength. If you use enough rebar in your hearth slab it is not going to sag or crack with the weight of an oven, especially a smaller cast one. I did use hollow cinderblocks with rebar and concrete cores - are you going to mortar your bricks together to add some stability?

[Mullster]

YesJRPizza going to mortar them all

[Mullster]

Progress pic - first time bricklaying - seems ok so far...just in a 40 minute queue for some more mortar mix now!

[aaronpizza]

Mullster, in your homebrew have ou sourced your clay yet? I can't seem to find a clay in powder form - it's mean to be super cheap?

Looking good btw!

[aaronpizza]

Progress pic - first time bricklaying - seems ok so far...just in a 40 minute queue for some more mortar mix now!

I rushed my last comment and didn't see your progress, it looks good, the only difference I'm going todo is put two angles on the front of the wall, purely for stability, the weight of the top will mean it will be stable but just in case.

Are you going to render the outside of the concreate blocks ?

[Mullster]

aaronpizza yes I am planning to render the blocks but not as an immediate priority - think I’ll leave that until the first pizza has been tasted unless anyway points out a good reason not too!

as for the clay to be honest I only starting looking yesterday. I was thinking to post a question about whether some of the fire cement products are the equivalent or not. I think I did find 20kg bags of fire clay for about £30.

What about yourself?

[Mullster]

This is where I finished the weekend - a 4th later and the divide in the centre to build

[Kvanbael]

Hey Mullster, just found your build-thread. No way back now. I also did many versions of my brick layout... except that I did my iterations with LEGO bricks :-). I'm a bit ahead, but with your casted dome, you'll be smelling oregano sooner than me. Best of luck with the build.