Just bought a fixer upper with a gawdy, outdated tiled (cluster f*** of stone, porcelain, and ceramic) wood burning fireplace surround. It's nestled in the corner of two walls, and we need to bring one one of the walls out about 4-6 inches which means we need to frame over the fireplace (making the fireplace deeper) and would like to have a cement finish surround. How far do the framing studs need to be from the opening? How can I accomplish a cement finish without tearing out old tile?