Reading post after post, lots of info in this forum, awesome. Another question I have is in regards to semi circular openings. Is a 20 in wide semi circular opening , which would be 10 in high enough for a 42 in semi circular dome? You could add another 2.5 inches of height to each jamb to get to 12.5 in. Has anyone constructed an oven with these dimensions? I personally like the looks of a semi circular arch.