I have a new century stove that I hope to install soon. It is already getting below zero here. I have never installed a stove. I plane to intal in my living room through the wall with the chimney. I read a little on NFPA 211 and my stove has a rear clearance of 14". I would like to reduce this so the stove an below platform wont have to stick out as much. I thought of building a brick or stone backing against the wall which according to the table and if my math is good this would reduce 33% to about 9" is this right? If it is I will get double wall pipe for interior. And do I need to go out 18" or 16" in front of stove with the platform?