When venting through a 100% brick wall (no drywall, no plaster, no lath, no studs, etc etc just brick and mortar) what is the diameter of the smallest circular hole that can be used for a stove that has a 6" vent, given code restrictions and available venting components? I asked at one company and was told the circle would have to be 14.5" diameter. Although I am completely inexperienced at this, having never had a wood stove, 14.5" seems like an awfully big hole to me for a 6" stove-vent. Is the O.D. of double-walled 6" I.D. chimney pipe 14.5" ? Are smaller-diameter thimbles available for non-combustible walls that would still meet code?