I've been getting by OK with my stubby little 11' chimney, but getting tired of fighting with draft issues, dirty glass,etc. So I've decided to bite the bullet and add a section of class A and add roof braces. I have no manual for my stove and internet searches for ideal chimney height are very vague. With a very low pitched roof, I will have to add braces regardless. So any ideas on how much higher to go? I read on another post to try just jamming a piece of single wall on top and experimenting, but I think that the insulated class A would have different characteristics.