New install on a Quadrafire 3100 Millennium and have questions on stove clearances. Spec sheet says 17" to 6" single wall pipe and 8.5" on stove corners on a corner install. I'm going to go with 18" to stove pipe thats standard. I put up walls 1" away from drywall with 1/2" cement board and porcelain tile. I have several questions. Is the 18" clearance to the back drywall or the non-combustible walls I put up and is the corner clearance of 8.5"to the drywall or the non-combustible walls. I forgot to mention I have a 1.5" gap at the bottom of the walls and the same cement board and porcelain tile on the floor. Also have back and bottom shields on the stove. Install is a thru the ceiling and then thru the roof. I can't get a straight pipe thru the rafters the stove sits below in the middle of the rafters so I'm going to use an elbow to go thru the ceiling 4 inches over. I hate this and would really prefer a straight shot thru the ceiling and roof. My last stove I had to move the pipe 4" over thru the ceiling/roof and I never had a great draft and it was always a pain to clean the pipe. Any one else have this problem. I appreciate any help on this.