[djhurt1]

I replaced the aging cast iron waste pipes with 4" PVC. The main pipe in the attached pic ended up really snug against the joist despite dry fitting and marking everything. I had to nudge it a bit over to pop up into the hole. Now of course it squeaks whenever someone sits on the crapper above. I'd love some suggestions of what my options are if any.

I've considered notching out the joist further and sistering up another. It's already notched quite a bit as you can somewhat see. That wasn't done by me and has been like that since we've lived here, so it's already considerably weakened.

 

[JIMMIEM]

I'd put some wood shims between the joist and sub floor. This will prevent the subfloor and pipe from moving downward when somebody moves onto the floor and toilet above. Just put the shims in hand tight when the bathroom is unoccupied. Don't hammer them in to avoid raising the floor in another area and causing another squeak spot.

 

[djhurt1]

I'd put some wood shims between the joist and sub floor.

Thank you for the suggestion! I tried slipping a couple shims in just now but it's pretty tight. Unless I hammer them in, I don't think they're going to go in.

 

[JIMMIEM]

Thank you for the suggestion! I tried slipping a couple shims in just now but it's pretty tight. Unless I hammer them in, I don't think they're going to go in.

Hammer if you have to. Can you get shims in from both sides?
Shim the cross blocking too.
It doesn't take much movement to cause a squeak and a real small gap is all it takes to allow movement (no pun intended).