Hello, I've been lurking on this forum for quite a while, and have learned a lot, what a great site. I would like some advise on a problem I have. I have a cabin that I recently purchased, it came with a manufactured fireplace that drafted poorly and threw no heat whatsoever. I thought, no big deal, I can tear it out and install an insert or freestanding stove in its place. The chimney has cultured stone on it, so I assumed that it was constructed with cinder block, with the stone adhered to that. Unfortunately, what I found was a 2x4 framed chase with OSB sheathing. The mesh, scratch coat and stone was then attached to that. To make my day even better the chimney crown has been leaking, so now a fair amount of the bottom is rotten. How do I create non-combustible surfaces within the hole in the wall I now have, so that I can install a stove? At this point I am leaning toward a freestanding stove so that the pipe is the only thing going into the cavity. In one of the pictures you can see that there is a 12" pipe (single wall) that runs the length of the chimney and is anchored in the chimney crown cement. Can I run a pipe inside that? The original manufactured fireplace also has a 8" SS single wall pipe that ran inside of the 12", any way to utilize that? I've attached pictures to help. Thanks