Moving a tub drain

[hj]

Right

Slogan: "nothing strikes fear, in the heart of a carpenter, like seeing the plumber go by with a sawzall in his hands..."

It is intentional. I was doing a motel years ago and the floors were 1 2/8" t&G. Since this would be the finished floor portions had to be "removed" in order to install the plumbing. It so happened that my neighbor was the carpenter foreman, so I asked him to cut the floors so I could put the plumbing in. He said, "That is the finished floor, so once we put it down we are done with it". I told him, "That once I cut the piece out, he would have to put it back and it would be a lot easier for him to replace a piece he took out, than the one I intended to remove." He decided it would be better to cut the floors himself.

 

[Jadnashua]

There is a big reason why you don't want to notch the top or bottom of a joist...the fibers along the outer edges are either in tension or compression...they are what provide the majority of the strength. Cutting there weakens it significantly more than cutting a hole in the middle.

If you went back to where the 1.5" tub drain was, you'd have to go all the way back to the stack, or where it is already 2". Since you'd have to cut out the wye, you could probably lower it to make the 2" connection, which would give you more leaway and keep the holes near the middle of the joists.