30" cast corner build UK

[Shaunster]

Hi everyone, I have been reading this forum for a while getting tips and ideas and looking at all the great builds for inspiration. I am building an oven which is 30" internal in a corner position, I have done the curing fires now plan for first pizza this week.

Started off with a 5" concrete foundation, then dry stacked blocks and concrete/rebarred every other hole. 4" thick slab on the top. Then the floor, 3" of calcium silicate board then 3" firebricks. The dome was cast using a castable refractory over a sand mould, I had heard people saying it was hard to work with but I found it not too bad, just dont mix up too much at a time, I had a little slumping at the bottom but apart from that the casting went well. I left it 24 hours then removed the sand and bricks from the inside which was quite a satisfying job seeing the dome.

[Shaunster]

The dome came out well so I moved onto the vent. I have a heat break between the dome and vent which I filled with ceramic rope and vermicrete. I cast the vent in place against the dome because I wanted to keep the entry as shallow as possible which meant the casting had to go over the dome so the base plate would fit, sand was used between the dome and the new cast so I could lift it off and remove the form work and sand then put the vermicrete over the dome before lifting the vent into place again. I am using a 150mm internal twin wall flue, and mounted to the vent using a base plate, I set the threaded rod into the cast so the base plate could be bolted in place later. I tried to keep the entry to the oven shallow and get a inverted funnel upto the chimney.

[david s]

Good job, you’ve obviously been researching your build well. I’d guess about 4 x more time spent on researching than actual building, all part of the fun. But i’d Also bet around 10 x faster than a brick build.

[fox]

Looks great and 30”” inch is a very sensible size.
I can’t quite work out if you cast your dome around the floor bricks, if you did... did you leave an expansion gap?

[Shaunster]

Good job, you’ve obviously been researching your build well. I’d guess about 4 x more time spent on researching than actual building, all part of the fun. But i’d Also bet around 10 x faster than a brick build.

I spent lots of time reading and re-reading this forum and a lot of your posts. I think casting is a lot faster than brick, but also brick wasn’t feasible in this tight corner space and the oven internal would had been smaller because the walls are that much thicker.

[Shaunster]

Looks great and 30”” inch is a very sensible size.
I can’t quite work out if you cast your dome around the floor bricks, if you did... did you leave an expansion gap?

I cast the dome around the floor. I put a strip of cardboard around the floor before casting. I had read about this the theory being it should burn away leaving a small gap.

[fox]

That sounds just about right.

[david s]

I hope you left enough room at the back of the oven for the insulation. It appears that you are very close to the walls and rendering against those tight spaces is a real bitch. An enclosure is a far easier way than an igloo for a corner build because you don’t have those tight spaces to render into, leaving a useless space at the back of the oven. For an enclosure the walls either side can act as your enclosure walls reducing labour and material cost by half. If doing an igloo style it is easier to integrate the oven into the walls. Pic doesn’t show it really clearly, but this is how this one is done.Yo can just fill the corner at the back with empty plastic bottles covered in vermicrete.

[Shaunster]

Insulation around the dome is 3 layers of blanket. This leaves a 60mm gap at the very closest to the walls for the rendering, its tight but it was either that or no oven! If I enclosed the oven the structure would encroach over the kitchen window so it wasn’t an option in this spot sadly.

[david s]

Ok, if that is your plan then do the drying fires after one layer of blanket. Applying render layers directly over blanket can be challenging but not impossible. The normal procedure is blanket vermicrete render.

[Shaunster]

Ok, if that is your plan then do the drying fires after one layer of blanket. Applying render layers directly over blanket can be challenging but not impossible. The normal procedure is blanket vermicrete render.

Thanks. I had already done the first fires, I put all the insulation on rather than just one layer hopefully it wont cause any problems.

[david s]

No, it’s just extra barrier for the moisture to find its way out. Start cooking, try roasting a couple of chickens with the stored heat before you add any render layers.

[Shaunster]

Next up I did the outer brickwork. There is an air gap between the outer arch and the refractory vent, I think I will fill it with something as the air gap looks unsightly. The Outer brick was built up and the hollow inside was filled with loose vermiculite and the top flattened off with a lean mix of vermicrete to provide a flat surface for the capping tiles to sit on.

[Shaunster]

Rendered the dome in two coats and left a hole in the top for a vent. I will paint the dome after some more fires. Rendering in those tight areas wasnt easy, I trowelled it on best I could then let it set up a bit before using a sponge float to smooth it and get the shape. I am using quarry tiles for the countertop and floor, they are called brown flame and are a nice two tone shade.

[fox]

Looks fab, I must say I would of been tempted to build a box and roof that went back to the wall but it looks great anyway.