I have a bathroom upstairs want to move it. But where I want to move it to the joists run the wrong way. I would have to cut the joists but I dont want to do that any suggestions. What size does tthe toilet drain have to be?
Tough situation, you can cut joists, but they must be reinforced, which makes them bigger, and that is what you are trying to avoid. Size depends on local code, length to the main, but is usually 3 or 4".