I have an old house with shiplap walls. Some of the chimneys are encased in shiplap or tongue in groove boards. I am installing sheetrock over the wood. The stovepipe enters the chimney through a hole in the sheetrock and the wood. In the picture you can see where I removed some of the tongue in groove to show the chimney behind it. What is the proper way to install a stovepipe in this situation?