nortcan wrote:At first I was supposed to make it the way you described but the so little space at the rear directed me upside. Just hoping not to arrive in front of a roof chevron.
If you have 10 inches to the wall from the smoke pipe then a single metal heat shield spaced 1 inch out from the wall will be enough. Bright galvanized or copper is very effective,less so if you paint it with heat resistant paint. Cement board is not a good heat shield.
You could also consider in addition, a heat shield standing on the floor behind the stove. Something like a fireplace fire screen only with sheet metal to replace the screen. Curved it would look nice. This would also shield the wood window moldings.
If you drill a 1/8 inch hole in the ceiling in the center of where the smoke pipe will go, then by using a plumb bob in the attic you can check for clearance to the roof chevrons. The roof flashing for coal should be either stainless or aluminum, not galvanized. Going straight up will be easier and cheaper than through the wall and have less turns to the pipe.