I can appreciate what Im1999 is saying. How ever that is all based on manufacturers establishing a starting point. So you can't be over cautious until you know where the line is. I made a call to englander for some clarification. After being on hold for almost 2 hours ( understandable do to it being the start of heating season, however the response was follow the instructions of the stove pipe company. But at the end of the conversation I had a building code question and the answer was englander specs should be followed. I'm still confused.