One of the problems with a clay oven seems to be the amount of shrinking that happens to the clay during the drying process. In particular if you build a brick arch you can expect to have a gap between the clay and the brickwork.
I am wondering if anyone has experimented with wall ties in the brick arch and burying them in the clay to try and hold it all in place? ... Or maybe even some sort of wire mesh?
Don't worry about the gap that appears between arch and dome, this is easily filled. I haven't shown it in any of my pics but I've now filled this (using a thin tool to push clay right into the gap) and it hasn't re-opened.
I've not built one, but i always wondered about building the clay onto a brick arch which supports it, and creates the chimney vent, rather than building the oven upto, or finishing with a brick arch infront of the cob.