To those who followed my other post, going straight up off stove isn't going to work because of cost. Also, converting existing masonry chimney to class A would be cost prohibitive as well. I need to add some height to resolve draft and wind issues. What is the maximum height for a freestanding masonry chimney without bracing? Currently, it comes about six feet off a flat roof. How much higher could I go without bracing it? I'd like to add about four more feet. It is the 15.5 inch x 7.5 inch masonry blocks that are used with a 8 inch x 8 inch clay liner. I attached a pic. I added two more feet to what you see in this pic. Also, when determining the minimum required height for a chimney, do you factor in the vertical rise your double wall stove pipe adds? I.e. If My chimney is only 9 feet high from where the stove pipe enters to the top, but I have a vertical rise of 2 feet with the stove pipe, then I'd only need to add 3 more feet to the chimney for overall height of 14 feet.