@Guamaque - Thanks! That's actually what I have surrounding the bottles in the insulation layer. It's a mix of perlite with clay slip. Initially I was using sawdust with clay slip, but I found the perlite/clay mixture MUCH easier to work with. After the dome dries out and I cure it, I'm planning on going over the clay dome with the perlite/clay mixture out to the edges of the bricks. That should give me 4-5 inches of insulation around the outside of the dome...hopefully that'll be enough. I'd like to use this for baking/roasting too.
@caliking - The entry/arch is 10.5 inches tall, and the top of the inside of the dome is right at 16 inches. I've read everywhere from 63% - 67% entry to dome height, so I'm roughly 65%...hopefully that will work. If need be, I can close it off by building up clay inside the edges of the entry. Hopefully I don't need to open it up more!
Weber OTG 22.5 Kettle / Char-Griller Outlaw / Backwoods Party
Always remember that [COLOR=red][I]you[/I][/COLOR] are [COLOR=red]unique[/COLOR] and [COLOR=red]special[/COLOR], just like [COLOR=red][I]everybody else[/I][/COLOR]. :mrgreen: