I want to install a toilet in my upstairs bedroom. I was told that I cannot connect to the 3" vent line for the downstairs toilets. the main reason being that a vacuum will be created when we flush the upstairs toilet and cause the water to be removed from the downstairs toilets. also that any home inspector will not pass the permits with that kind of configuration. He recommended that I run a drain/vent line using the exterior cleanout port, up the exterior of my home directly to the room in question.
has anyone ever done this before? I cant seem to find any information online about this. what should I be worried about with this "exterior" drain? Any information would be helpful.