Waste pipe through floor joists?
Hi everyone, I really need some advise. I am moving a toilet, well, not me personally, to the other side of a bathroom. The room is 10x10 and is on the second floor. The toilet will be moved directly across from where it sits presently. Where the toilet is now will be the sink and vanity. At this time, the joists are not exposed so I am going on the assumption that they are 2x10's. One contractor says he will run the pipe to the waste through the joists. A plumber says never cut through the joists and a new waste pipe will need to be installed. If the floor joists are running in such a way that they need to be cut to allow for the waste pipe (3Inches?) to cross the room, how much structural damage will this cause? and will the floor have enough support? Is there some way to reinforce the joists if they need to be cut into? I would like to know all my options before contracting the remodel. Any advice is greatly appreciated.