How to connect this plumbing

[Sqrjay]

I’m trying to get rid of a drop ceiling. I got rid of it, and then found this plumbing.

From the left - there is a toilet and shower with a vent with 3” ABS

Going out from the wall - is a sink and vent with 1 1/2”

From the right - there is a shower and vent with 2”

Coming straight down - there is a toilet with 3” - this had no vent. It just connected to the top of a double sanitary tee

I’ve cut all this out and trying to figure out how to redo it. I’ve got the joists reinforced so that I can run the 3” pipe through them. I’m clear on how to handle the hot/cold and electrical. I’m just not sure how to best join the plumbing together. I need it to all go down this small partition wall that sticks out from the exterior wall.


I want to add a vent to the toilet in the middle since it never had one. I never had any problems, but not even sure why not. I wanted to either tie into the vent for the shower to the right or the vent for the sink that goes out from the wall. Would this work? If not, then I can run a new vent up through the attic from here.


To make all this fit, I was wondering how to best do it inside that partition wall. Can I just use a series of 3 wye or sanitary tee stacked on top of each either in the partition wall?

Out the top would be the new vent for the toilet in the middle.

First connection would be the toilet from the middle so that it would be vented.

I was just going to tie the sink/vent 1 1/2” into the toilet/vent 3” coming from the left. I could then connect it in the next wye or sanitary tee below the first.

Finally, connect another wye or sanitary tee below it for the shower coming from the right.


This isn’t going to be inspected, but I don’t want to create problems either. My biggest concern is if things are going to get clogged easily or traps get siphoned. I wasn’t sure if my idea would work. I don’t know if because things are vented already closer to the fixtures that I can just tie it all together this way, or will this cause a siphon problem.

 

[Breplum]

Quite frankly, you should hire a small, local, licensed plumbing contractor.

 

[Sponsor]

 

[wwhitney]

So, my understanding is that all of the fixtures you've labeled with "/vent" have a proper dry vent take off upstream, not shown in the picture. Then any of those fixtures can wet vent the one WC that is not so labeled. You don't have to add an additional dry vent for that WC.

Also, my understanding is that you wish to raise up all the horizontal runs under the joists into the joist bays. You can do that if your holes through the joists are at most 1/3 the joist depth and are at least 2" clear from the top and bottom edges, or if you use an alternative approved reinforcement. The wall with the current stack is remaining, and you want everything hidden in the floor system and wall.

Then if that's all correct, you can use a connectivity like I've marked up on your photo below. To show the pipe within the joists, I've only drawn the segments that would not be obscured by the joists. Red is 3", blue is 2", and green is 1.5".

On the left, the 3" vented WC drain gets raised up into the joists, and it connects to the 1.5" vented lav drain with a horizontal combo. Then it turns down into the stack with a quarter bend (not shown, as it would be behind that joist.)

Then for the other WC, it's a bit of trouble that it's not currently over the wall. If it were, you could just have the shower drain (raised into the joists) join it via a san-tee (thereby wet venting it); then after going through the top plate, it can hit a 45 to a wye on the stack.

However, since it's not lined up over the wall, within the joist bay it has to jog over with a pair of 45s to enter the wall (only the bottom-most of which I've drawn). Then in the wall it can hit a wye's branch inlet, the straight inlet of which gets the shower drain. The shower drain has been raised up into the joists and move some to the right, to be able to hit that wye straight entry.

Anyway, that's one option.

Cheers, Wayne

 

[Sqrjay]

So, my understanding is that all of the fixtures you've labeled with "/vent" have a proper dry vent take off upstream, not shown in the picture. Then any of those fixtures can wet vent the one WC that is not so labeled. You don't have to add an additional dry vent for that WC.

Also, my understanding is that you wish to raise up all the horizontal runs under the joists into the joist bays. You can do that if your holes through the joists are at most 1/3 the joist depth and are at least 2" clear from the top and bottom edges, or if you use an alternative approved reinforcement. The wall with the current stack is remaining, and you want everything hidden in the floor system and wall.

Then if that's all correct, you can use a connectivity like I've marked up on your photo below. To show the pipe within the joists, I've only drawn the segments that would not be obscured by the joists. Red is 3", blue is 2", and green is 1.5".

On the left, the 3" vented WC drain gets raised up into the joists, and it connects to the 1.5" vented lav drain with a horizontal combo. Then it turns down into the stack with a quarter bend (not shown, as it would be behind that joist.)

Then for the other WC, it's a bit of trouble that it's not currently over the wall. If it were, you could just have the shower drain (raised into the joists) join it via a san-tee (thereby wet venting it); then after going through the top plate, it can hit a 45 to a wye on the stack.

However, since it's not lined up over the wall, within the joist bay it has to jog over with a pair of 45s to enter the wall (only the bottom-most of which I've drawn). Then in the wall it can hit a wye's branch inlet, the straight inlet of which gets the shower drain. The shower drain has been raised up into the joists and move some to the right, to be able to hit that wye straight entry.

Anyway, that's one option.

Cheers, Wayne


View attachment 78726

You understood correctly exactly what I'm trying to accomplish.

I have some steel reinforcements from joist repair to allow me to add up to 6" holes that I'll be adding (and maybe making 4-4.5" holes). You can google 2810HR if you are curious.

If I'm understanding you correctly, then it should look like the above. Does this look correct? A combo wye and 2 wye?

 

[wwhitney]

Your drawing matches my drawing. I think that's an acceptable arrangement, it would be simpler (as I described) if the WC were directly over the wall. If you took a photo looking more or less straight up, with the camera under the joist bay that is above the wall, it would help me see if there's a better option, but it's not too likely that would change my suggestion.

Cheers, Wayne

 

[Sqrjay]

Your drawing matches my drawing. I think that's an acceptable arrangement, it would be simpler (as I described) if the WC were directly over the wall. If you took a photo looking more or less straight up, with the camera under the joist bay that is above the wall, it would help me see if there's a better option, but it's not too likely that would change my suggestion.

Cheers, Wayne

Here is a pic looking up.

 

[wwhitney]

Here's one alternate idea for the WC and shower wet connection that may or may not work for you:

Take a 3" wye, orient the the outlet vertical with the branch inlet pointing towards the WC location. Raise it up just enough so that it fits in your wall, i.e. the wider part is up in the joist bay. Then put a 3x2 reducer in the straight inlet, and a street 2" quarter bend into that.

If the resulting elevation of the street 2" quarter bend inlet is a reasonable elevation for your shower drain (given the constraints on the shower trap height and the need for a 1/4" per foot slope, and that holes in the joists have to be at least 2" clear from both top and bottom), then you could use that. The branch inlet on the 3" wye gets a (likely street) 45 to turn vertical under the closet flange location.

Cheers, Wayne

 

[Sqrjay]

Here's one alternate idea for the WC and shower wet connection that may or may not work for you:

Take a 3" wye, orient the the outlet vertical with the branch inlet pointing towards the WC location. Raise it up just enough so that it fits in your wall, i.e. the wider part is up in the joist bay. Then put a 3x2 reducer in the straight inlet, and a street 2" quarter bend into that.

If the resulting elevation of the street 2" quarter bend inlet is a reasonable elevation for your shower drain (given the constraints on the shower trap height and the need for a 1/4" per foot slope, and that holes in the joists have to be at least 2" clear from both top and bottom), then you could use that. The branch inlet on the 3" wye gets a (likely street) 45 to turn vertical under the closet flange location.

Cheers, Wayne

I think I follow. Can you confirm the image below is what you are suggesting? I would have to add a little bit of space before the 2 45's from the WC to get it down enough to have the 2" be at the 2" point on the joist. Then I'd just tie it into the other run with another wye like the original design? It looks like I'd have just enough space to do this without it being too cramped.

 

[wwhitney]

Actually, that's my original proposal. Which is good/fine if it fits and you're happy with it. You have a reducer coupling instead of a reducing bushing, not sure if it has any performance benefit, a bushing takes up less space.

My second idea removes the 3" 45 that is above the wye in your photo, so the wye through path is plumb. Then the 2" quarter bend outlet is also plumb, and you use a 45 below the wye to head towards the wye in the stack. So it's just a different arrangement of the same fittings, actually.

Whichever you like or fits better or gives you a better elevation for the shower rain.

Cheers, Wayne

 

[Sqrjay]

Actually, that's my original proposal. Which is good/fine if it fits and you're happy with it. You have a reducer coupling instead of a reducing bushing, not sure if it has any performance benefit, a bushing takes up less space.

My second idea removes the 3" 45 that is above the wye in your photo, so the wye through path is plumb. Then the 2" quarter bend outlet is also plumb, and you use a 45 below the wye to head towards the wye in the stack. So it's just a different arrangement of the same fittings, actually.

Whichever you like or fits better or gives you a better elevation for the shower rain.

Cheers, Wayne

After stepping back, now I do see it is you original idea.

I think I'm just going to stick with this one since it will fit perfectly.

 

[Tuttles Revenge]

I would get a bushing.. working with fittings that close together is a PITA... anything that makes working easier.

 

[Reach4]

I think you probably start low and work high, but I could be wrong. In other words, add the path thru the floor after putting the wye is in place. Is that the normal order of installing drain fittings?

I would be considering something that allows adjustment after gluing. Shielded coupling and Charlotte ConnecTite fittings look useful if you are not confident in getting the angle right the first time when gluing.