Ok, so I decided to take the plunge and upgrade my metal firebox fireplace to a Drolet Savannah wood burning stove. I've built the hearth and will be hanging fire resistant drywall (Type X) above and around the hearth. My problem/question is this; I only have 9-10 inches clearance behind the stove pipe to the rear wall, and would like to know if the drywall is considered a combustible structure. Everything I find about installing single wall pipe indicates that 18" min clearance is required to combustibles, is 10" ok for fire resistant drywall and single wall pipe clearance? I could always install double wall stove pipe, but it's significantly more expensive and if I can get away w/ single why then why not. Thanks for any info/pointers on this.