Building the dome

[Giovanni Rossi]

You probably want something in the middle of those two designs. The intersection of the dome and the slab is the most prone to moisture infiltration.
I would extend the vermicrete layer beyond the floor and stop the blanket at the top of the vermicrete. That keeps the blanket away from the slab and provides insulation around the perimeter of the oven floor.

[frank1985]

I was leaning more towards that as well, having it rest on the slab, but I guess my main concern is how to best seal up the vermicrete slab on the sides/perimeter. Could I just render over it as part of the dome's render layer? Maybe after painting the exposed vermicrete with water resistant masonry paint? Perhaps some flashing tape would work better...? Tagging in david s SableSprings

[Giovanni Rossi]

I tried to avoid water infiltration at the slab as much as possible by resting the oven assembly on a layer of Foamglas (gave more floor insulation too).
Check out Mike's and David's recent comments on Oven Rebuild Ireland.