Toilet waste pipe relocation headache

[shacky003]

Greetings all,
I've got an interesting issue, and each possible solution seems to hit a dead-end..

I have a townhouse, and am remodeling a second floor bathroom. I'm basically flipping where both the toilet and tub/shower go, so that it's more of an open bathroom, instead of a galley that it was.

Within this task, the tub plumbing and drain are easy to relocate as they will run between the same two floor joists, just ~4 feet down the joists..

The toilet on the other hand is a pickle.. The old toilet location had the back of the toilet up against the side wall of the town-home that is a shared wall, with the plumbing going down it, through the first floor (living room wall) and into the basement. The current waste pipe goes past the cut living-room bottom plate, and goes through a cut in the plate towards the neighbors basement (it connects to his sewer connection as he's on an end unit, and it's closer. We also have a couple of sink drain connections coming into our sewer pipe from the opposite side neighbor.

What I would like to do is to have the waste pipe in the bathroom go down into the floor two joists over from where it currently resides. I've read that I can't put a hole in the joists as it would have to be slightly over what is allowed due to it being a 3" pipe, and the joists are 2x10. I don't see a way around this with being legal with sistering, boxing, etc.. Soo, on to other possible options.

I was thinking I could run the new waste line down the same wall towards the basement, then tie it into the existing pipe two studs over, but that would involve drilling through the studs that are load-bearing from the second floor weight. Even if I opened up the living room wall downstairs, I could only put a small hole as per code into the studs, or a slightly larger one if I doubled up the studs (up to two each, that I need to go through) but the holes would be slightly too big to be allowed) - That is, if they even framed properly - the bathroom wall (mind you, not load-bearing has a 2x6 plate, but has 2x4 stud completely randomly spaced and staggered on my side vs the neighbors side.. One would hope there are 2x6 studs below..

This leads to possible option 3: Run the new waste pipe down the walls parallel to the old one (but two studs over) and once it gets into the basement, make my own run all the way across the house to the sewer connection on the other side. This presents issues as well. I have a drop ceiling in the basement (great for access) but bad for additions because when I drop the pipe into the basement between the joists, I've got to stay above a steel beam that holds them up about 10 feet away, then would need to drop the pipe under a number of HVAC ducting at the other side of the house, but then come back up to the sewer connection that is just below the bottom of the joists in an unfinished area of the basement, which all ties into a first floor half bath. Obviously I can't have the pipe go uphill, and have to keep a steady small angle down for flow.. So I'm out of ideas..

If there was a way to use some type of steel hole supports on the 2x6 studs like they have for 2" pipe on 2x4's that would be great, but I haven't seen anything like that at the size needed.. Is there another solution to tie the new and old pipe's together after I get out of the second floor, such as boxing in an angled pipe through the two studs in the way, or some other thing I haven't thought of?

I've thought of drilling through the second floor joists, first floor joists (both 2x10) and that's a no-go for a 3" pipe, as well as trying to figure out how to get a Y into the living-room wall downstairs where the existing pipe is, but can't figure out a way as it's load-bearing (although the plate and header joist are completely cut through on the second floor to let the waste pipe drop down into the first floor)

I'll take some pics and/or make diagrams to try to help..


Headaches all over..

 

[shacky003]

All of this could also be moot as I've read in some places drilling for a 3" pipe into a 2x10 beam is ok as long as you keep the right grade, but elsewhere I've read that the hole is too big.. I'd have no problem sistering, and it would make life much easier, and it would be a much faster way to get to a beer at the end of the job.. Confused.. If I was able to go through the two floor joists from old toilet location to new location, I would need to go through two joists.

 

[Sponsor]

 

[hj]

All of these "descriptions" make my head hurt as I try to figure out how they are running and the directions. How about a picture of what you have or a drawing of what you THINK you can do?

 

[Jadziedzic]

Maximum size of a hole in a joist is D/3 - or 3" for a 2x10; that won't fit a 3" (ID) pipe.

More details at https://engineering.purdue.edu/~jliu/courses/CE479/extras/Notching_&_Boring_Guide_A11.pdf

 

[shacky003]

Sorry for the confusion, and lack of graphic detail..

Here is something I just made up that looks the work of a 4 year old, but it'll do:

The townhouse shared side wall is in green, with 2x4 studs and currently a 3 inch waste and vent pipe in red.

I need to extend the old waste pipe over to the new location, but only have 2x10 joists to work with. Going under them isn't an option as it's in the middle of the living-room ceiling at that point. The "new" graphic shows what I would need to do in going through two 2x10 joists.

While I know the rule is D/3, would a sister on each of the two joists increase that at all?

I can't have the waste pipe go from the new toilet location over to the wall, then bring it in the wall to the original location as that green wall is load-bearing.

I would much rather just take the waste pipe straight to the right and go down the wall like the original, but it would be impossible to tie into that 3 inch stack in the basement as the moment it goes through the sill/plate in the bottom of the living-room wall, it does a bend into the neighbors basement where it connects to the sewer.

If I ran a new stack down to the basement, I wouldn't be able to get to our other sewer connections without bringing the pipe down to like 4 feet off the ground in the middle of the finished basement due to obstacles, and the needed grade.. I could go around most obstacles in the basement to get to our main sewer connection, but that would be a total of at least 5o+ feet of new pipe.

If I say the heck with the shared wall, and try to take the waste pipe to the left (as the 1 1/2 inch pipe goes) I would run into joists-turned-air-return and then stair framing.. (The 1 1/2" pipe goes 2-3 feet out of the bath, then goes through I believe two joists, then down into the first floor bath - so that path is out)

I have access to everything from above (I've pulled most of the floor up - a slow bath drain leak started all this.) The underside of these joists and drywall is decorative mud on the living-room ceiling..

 

[Jadnashua]

Run the drain over to the wall and then down, not across multiple joists. You do not show any venting in there, and that can be as important as the drainage. A 3" drain pipe is 3.5" in diameter, and to keep it from creaking as the pvc or abs expands and contracts, and because you'd never get things perfectly aligned, you need a bigger hole for clearance. Plus, consider you still need to maintain that 1/4"/foot slope, so you would not likely be able to keep the holes in all of the joists within the middle section, or close enough, even if they were taller. There are rules about how close to the end of the joist a hole can be as well, but I think you're far enough away that, with a smaller pipe (won't work with a toilet!), you probably could do it. It might get a bit tight with the tub drain, but you should be able to make it work.

 

[shacky003]

Thanks for the reply..

The current vent is part of the old layout pipe in the wall - they basically ran the stack from the basement up to the attic, putting in a T for the waste connection in the wall...

I guess I'll need to run the new stack down to the basement, and figure out how to tie in somewhere on the other side of the house (as the current stack vanishes into the other townhouse basement as soon as it gets to the bottom of the first floor) - tough pill to swallow needing to run 50+ feet of pipe to have a toilet moved three feet..

'tis life..

Thanks again
Mike

 

[Jadnashua]

A plumber being there, and able to see exactly what you have may be able to come up with a neater solution without as much work, materials, or effort...experience helps! NOte, that, one a pipe is used as a drain, it cannot be a vent...you need to vent the moved items properly as well as get the drainage properly.