Drain lines for basement bathroom and laundry

[NickLo]

Hello everyone. First post. This forum has been really helpful so thanks in advance for anything you can provide. I wanted to get some feedback from everyone on this mapping of these drain lines. Couple of things to note.
1. I'm in Maryland which uses the IPC to my knowledge.
2. Everything expect the 3 in drain (labeled) is 2in lines sch 40.
3. I will have p traps on the end connectors but it was a pain to try and draw those.
4. This is just for the drain lines since running supply lines is much easier and straight forward in my opinion.
5. The drain line running down right next to the double ST is also a ST but I forgot to label.

If anyone wouldn't mind looking at my layout and giving feedback I would appreciate it. Let me know if there's anything I missed, anything that's not to code or doesn't make sense. Thanks for all the help so far. I uploaded the attachment for review.

 

[wwhitney]

So you are showing just the drain/vent above the slab, and don't show the WC drain/vent or the shower drain/vent? Is the sink next to the laundry standpipe a laundry sink? And the two sinks at the other end are both lavs?

- You'll probably want to use the two lavs to wet vent the WC and shower, so that will require keeping the laundry standpipe and sink drains separate from the lav/WC/shower drains until those three bathroom fixture drains have combined for horizontal wet venting. Then the laundry drains can join the combined bathroom drains.

- The only use for a san-tee in drainage is with the straight path vertical, and the side path coming in horizontal. Then the top opening can be a vent take-off, or it can be used to combine a vertical and horizontal drain. [The IPC also allows you to use it with the straight path horizontal, and the side path point up for a vent take-off, but a combo is better for that if you have room.]

- Normally you vent each trap before the fixture drain combines with another drain, but the IPC (in force in your area, I believe) does allow two fixture drains to be combined and a common vent to come off downstream of that combination point. So the configuration with the two lavs is OK (if unusual). More unusual would be to put a double san-tee or double fixture fitting in between the two lav trap arms.

- Likewise, the laundry standpipe and sink could combine on the horizontal like that, but then where the combined, unvented drain turns downward, you'd use a san-tee to take off a vertical vent. That vent would rise separately from the vent for the lavs, and the two vents could recombine at a height that is at least 6" above the flood rim of any of the associated fixtures. More typical would be to use stacked san-tees with vertical wet venting.

- Unfortunately, the IPC requires that when the laundry standpipe drain joins another drain, the combined drain has to be 3". So if you want to use a 2" laundry standpipe drain, you'd need to keep the laundry standpipe drain separate from the laundry sink drain. The IPC does have an option for a laundry standpipe and laundry sink to share a single trap, which would allow them both to be served by a common 2" drain line.

Cheers, Wayne

 

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[NickLo]

So you are showing just the drain/vent above the slab, and don't show the WC drain/vent or the shower drain/vent? Is the sink next to the laundry standpipe a laundry sink? And the two sinks at the other end are both lavs?

- You'll probably want to use the two lavs to wet vent the WC and shower, so that will require keeping the laundry standpipe and sink drains separate from the lav/WC/shower drains until those three bathroom fixture drains have combined for horizontal wet venting. Then the laundry drains can join the combined bathroom drains.

- The only use for a san-tee in drainage is with the straight path vertical, and the side path coming in horizontal. Then the top opening can be a vent take-off, or it can be used to combine a vertical and horizontal drain. [The IPC also allows you to use it with the straight path horizontal, and the side path point up for a vent take-off, but a combo is better for that if you have room.]

- Normally you vent each trap before the fixture drain combines with another drain, but the IPC (in force in your area, I believe) does allow two fixture drains to be combined and a common vent to come off downstream of that combination point. So the configuration with the two lavs is OK (if unusual). More unusual would be to put a double san-tee or double fixture fitting in between the two lav trap arms.

- Likewise, the laundry standpipe and sink could combine on the horizontal like that, but then where the combined, unvented drain turns downward, you'd use a san-tee to take off a vertical vent. That vent would rise separately from the vent for the lavs, and the two vents could recombine at a height that is at least 6" above the flood rim of any of the associated fixtures. More typical would be to use stacked san-tees with vertical wet venting.

- Unfortunately, the IPC requires that when the laundry standpipe drain joins another drain, the combined drain has to be 3". So if you want to use a 2" laundry standpipe drain, you'd need to keep the laundry standpipe drain separate from the laundry sink drain. The IPC does have an option for a laundry standpipe and laundry sink to share a single trap, which would allow them both to be served by a common 2" drain line.

Cheers, Wayne

Thanks for the input Wayne, I'll answer back as best I can and then have some follow on questions for you.

Yes, I am only showing what's above the slab. I just put circles to indicate the drains being there. The plan was to put in a sink right next to the laundry standpipe, so yes that's what the drawing was initially for. And yes, the two other drains would be for a double lav.

1. I'm most likely missing this so if you can help explain...Isn't the wet venting achieved with the way the rough in would be built below? The WC and Shower drain into the sewer pit and both 2in drains that go into the slab are vented by the vent stack. If I'm following you correctly, I should connect the laundry sink and standpipe up then then come over horizonal above the flood plane rather than the way I have it now?
2. So in the san tees I have in drainage is where the two lavs connect, currently where I have the 2nd pipe going into the slab (which if my first question is correct, I would move up) and the laundry standpipe which would get changed based on your last comment. So I should switch the double lav san tee to a combo?

Here is mod 1
https://imgur.com/a/XKS9y85

Here is mod 2

https://imgur.com/x5qQRHN

Thanks again for your help!

 

[wwhitney]

1) In re horizontal wet venting of the WC and the shower, I was commenting on how things have to be run in the slab. The two lav drains can combine in the wall, and the lav drain goes into the slab and picks up the WC and the shower. The laundry sink and standpipe have to remain as a separate horizontal drain in the slab, which only joins the other drains after the lav, WC, and shower have combined. That's because the lav/WC and lav/shower drain connections are the vent connections (horizontal wet venting) for the WC and shower, respectively, and the fixtures on the horizontal wet vent are restricted to bathrooms group fixtures.

2) The horizontal fitting where the two lav trap arms combine as drawn would need to be a combo; that's why I was explaining the limitations on san-tees, you can't use them flat to join drains. More usual would be to put the vertical lav drain between the two horizontal lav trap arms, and use a double san-tee/fixture fitting to bring the two lavs together at the vertical lav drain. And the way you've drawn the two trap arm suggests that the lavs are very close together; if their drains are not more than 30" apart horizontally, you have the option to plumb the lavs with a common trap (like a double kitchen sink), then you'd just need a single san-tee in the wall.

Cheers, Wayne

 

[NickLo]

1) In re horizontal wet venting of the WC and the shower, I was commenting on how things have to be run in the slab. The two lav drains can combine in the wall, and the lav drain goes into the slab and picks up the WC and the shower. The laundry sink and standpipe have to remain as a separate horizontal drain in the slab, which only joins the other drains after the lav, WC, and shower have combined. That's because the lav/WC and lav/shower drain connections are the vent connections (horizontal wet venting) for the WC and shower, respectively, and the fixtures on the horizontal wet vent are restricted to bathrooms group fixtures.

2) The horizontal fitting where the two lav trap arms combine as drawn would need to be a combo; that's why I was explaining the limitations on san-tees, you can't use them flat to join drains. More usual would be to put the vertical lav drain between the two horizontal lav trap arms, and use a double san-tee/fixture fitting to bring the two lavs together at the vertical lav drain. And the way you've drawn the two trap arm suggests that the lavs are very close together; if their drains are not more than 30" apart horizontally, you have the option to plumb the lavs with a common trap (like a double kitchen sink), then you'd just need a single san-tee in the wall.

Cheers, Wayne

1. Ok that makes sense. Is there any way I could know that without busting up concrete? I'm assuming with the rough in, they would account for a standpipe and separate wc/shower/lav for the bathroom.
2. Tracking on combo. I will make that change. The lav distance isn't to code/scale at the moment. I'm still trying to learn how to use this software, so it's been a little bit of a pain. If the drain pipe was closer, I would just do what you suggest, but I'm assuming I could also use a 90 to essentially move the drainage over to accommodate where the lavs would need to be based on the layout of the bathroom framing? I'll keep that distance in mind with the 30". I haven't picked up the vanity yet, but I think I would be able to do what you said.

Now that I'm tracking on where you're going, the links above may be pointless haha.

Thanks again Wayne.

 

[wwhitney]

Ah, you have an existing rough in below slab that you want to make use of? That wasn't clear to me. A picture or drawing showing the locations of the slab entries and pit would be helpful. You may need to investigate the connectivity with a camera.

Cheers, Wayne

 

[NickLo]

Ah, you have an existing rough in below slab that you want to make use of? That wasn't clear to me. A picture or drawing showing the locations of the slab entries and pit would be helpful. You may need to investigate the connectivity with a camera.

Cheers, Wayne

Yeah sorry if that wasn't clear. The 2 in pipes that go downward go into the slab. I have access those two drains, the WC drain and the shower drain. I know the shower drain is has a p trap in it, just gauging from the little bit of water that has stayed behind when I tested it.

But in terms of the drawings, with your recommendations, everything looks good? I'm going to get a permit pulled just so the inspector can tell me if there's anything else that isn't up to current code.

 

[wwhitney]

I can't really give you a final answer without updated drawings, plus it's hard to know what's going on under the slab. On the laundry drain, if you want to use the 2" drain line, under the IPC you either need to (a) use a laundry tub only, and have the washing machine discharge into the laundry tub or (b) plumb the standpipe and laundry tub with a single trap, as in IPC 802.4.3.1:

https://up.codes/viewer/maryland/ipc-2018/chapter/8/indirect-special-waste#802.4.3.1

(there's a nice diagram the IPC authors put out on that, if you search for it you should be able to find it).

Also, if you have (2) otherwise undifferentiated 2" slab entries, you'll need to figure out which one is which. Hopefully one of them (call it A) combines with the shower drain (or WC) and then the WC (or shower drain), and then the other one (call it B) comes in downstream of all three. If so, then A is the your lav drain, and B is your laundry drain; you can't swap them.

Cheers, Wayne

 

[NickLo]

@wwhitney , does https://imgur.com/MTdE5jU not get at what you're saying? I used b for a single trap. The standpipe is a little crude but goes into the single trap. Also, don't know if it helps, but here is the pic of what I'm working with... https://imgur.com/EweTkma

To your second point, guess having a camera (as mentioned above) is my best bet in tracing out the pipes, correct?

 

[wwhitney]

That drawing is fine on the sink side. And if the laundry side matches this drawing, that's OK too:

http://media.iccsafe.org/news/icc-enews/2018v15n13/2018SC-IPC802.pdf

Not sure about tracing out pipes, I haven't had to do it. I would think a camera would work, not sure if there is an easier way.

Cheers, Wayne

 

[NickLo]

That drawing is fine on the sink side. And if the laundry side matches this drawing, that's OK too:

http://media.iccsafe.org/news/icc-enews/2018v15n13/2018SC-IPC802.pdf

Not sure about tracing out pipes, I haven't had to do it. I would think a camera would work, not sure if there is an easier way.

Cheers, Wayne

Cool, Yeah that's kinda what I was going for, but that pic helps alot. Thanks for all the help again!

 

[NickLo]

That drawing is fine on the sink side. And if the laundry side matches this drawing, that's OK too:

http://media.iccsafe.org/news/icc-enews/2018v15n13/2018SC-IPC802.pdf

Not sure about tracing out pipes, I haven't had to do it. I would think a camera would work, not sure if there is an easier way.

Cheers, Wayne

@wwhitney - update for you and anyone else. Thanks again for all your help. So when I was making my layouts for the shower pan I will end up having to move the WC drain. So I went ahead and started busting out the concrete to hopefully determine the layouts of the rough in plumbing.
So far I can tell that the WC drain goes directly to what we call A. If they roughed out this house correctly (there is a inspection sticker on it when they did) is it safe to assume that drain B would be downstream or should I keep hammering away at the concrete?

 

[wwhitney]

I wouldn't assume. You need the drains to join up in this order: lavs (A) and WC join first; the shower joins in next ; then laundry (B) joins in last. (Or you could swap shower and WC if that's easier). So do what you need to do to be sure that's the order you have.

BTW, I forget if I mentioned it, since you have two lavs draining into a wet vent, the drain needs to be 2" starting at the point where the two lavs join. The vent can be 1-1/2".

Cheers, Wayne

 

[NickLo]

I wouldn't assume. You need the drains to join up in this order: lavs (A) and WC join first; the shower joins in next ; then laundry (B) joins in last. (Or you could swap shower and WC if that's easier). So do what you need to do to be sure that's the order you have.

BTW, I forget if I mentioned it, since you have two lavs draining into a wet vent, the drain needs to be 2" starting at the point where the two lavs join. The vent can be 1-1/2".

Cheers, Wayne

Ok, looks like I have a lot more concrete to jack up haha. You're right though, don't want to assume. Also I was planning to keep everything 2" including the vent since the vent up in the joists is already 2".

Thanks again for the quick reply.

 

[wwhitney]

A camera might be easier than a jack hammer. There are inexpensive USB cameras that would be suitable for at least one use. You can stick a camera down one pipe and a wire or snake down another, then at the intersection you should be able to see the snake coming in.

Cheers, Wayne

 

[NickLo]

A camera might be easier than a jack hammer. There are inexpensive USB cameras that would be suitable for at least one use. You can stick a camera down one pipe and a wire or snake down another, then at the intersection you should be able to see the snake coming in.

Cheers, Wayne

@wwhitney - Well I had the rotary hammer rented, so I figured I'd check it out anyway. Here is what I found.....

I made the first drawing just to show the lines since some of them were covered with plastic and dirt.
The shower drain and left 2" drain connect together. And the WC, right 2" drain connect and they all meet with a San Tee. The shower drain/2" A is connected with a 2x2x2 WYE it looks like and the same for the WC/2". So if I'm looking at this correctly, the bathroom "plumbing group" isn't technically separated from what would be the standpipe and utility drain. Thoughts?

https://imgur.com/cpFSFrS

https://imgur.com/BNj9P7o

 

[wwhitney]

and they all meet with a San Tee.

I don't understand this statement, as to what is meeting with a san-tee. There should be no san-tees under the slab, all the connections in your marked up photo should be wyes or combos.

[Just double checking--is the stud wall in your photo a temporary wall, and the wall is ultimately going to be where the two 2" vertical drains are?]

The conceptually simplest solution is to eliminate the left hand 2" riser in your last photo, then add a new 2" riser 4-8" to the left, with its own 2" drain running parallel and to the left of the shower drain. Then it ties into the 3" line just downstream of the shower wye.

Depending on how much room there is on the 3" line between the WC and shower connections, it might be easier (less concrete to break) to add a 3" x 2" wye in between the two current connections to the 3" line, and to use that new wye for the shower drain. So the shower drain coming out of the trap would continue to the right a bit farther than currently and then turn at a 45 to the new wye. The existing 2" riser would remain, with the current combo at the bottom replaced with a LT90.

Cheers, Wayne

 

[NickLo]

I don't understand this statement, as to what is meeting with a san-tee. There should be no san-tees under the slab, all the connections in your marked up photo should be wyes or combos.

[Just double checking--is the stud wall in your photo a temporary wall, and the wall is ultimately going to be where the two 2" vertical drains are?]

The conceptually simplest solution is to eliminate the left hand 2" riser in your last photo, then add a new 2" riser 4-8" to the left, with its own 2" drain running parallel and to the left of the shower drain. Then it ties into the 3" line just downstream of the shower wye.

Depending on how much room there is on the 3" line between the WC and shower connections, it might be easier (less concrete to break) to add a 3" x 2" wye in between the two current connections to the 3" line, and to use that new wye for the shower drain. So the shower drain coming out of the trap would continue to the right a bit farther than currently and then turn at a 45 to the new wye. The existing 2" riser would remain, with the current combo at the bottom replaced with a LT90.

Cheers, Wayne

Sorry, I stated that wrong. After the jackhammering I was enjoying a beer and most likely had one too many....

So they all connect with a wye. The Shower/Drain 1 (2" vertical pipe) is connected with a combo wye, and same with the WC/drain 2.

Yes, I'm not sure why they framed the wall offset to the drains but I am planning on tearing that down and centering the drains on it with a 2x6 wet wall.

I understand what your first solution is, but let me draw up your second since it's easier for me to visualize it and make sure I'm tracking on what you're describing.

Just a question but the 2 2" risers being on the same plumbing group: Why would they do that if it wasn't to code? Or was that not code back in '97?

Thanks again!
Nick

 

[NickLo]

I don't understand this statement, as to what is meeting with a san-tee. There should be no san-tees under the slab, all the connections in your marked up photo should be wyes or combos.

[Just double checking--is the stud wall in your photo a temporary wall, and the wall is ultimately going to be where the two 2" vertical drains are?]

The conceptually simplest solution is to eliminate the left hand 2" riser in your last photo, then add a new 2" riser 4-8" to the left, with its own 2" drain running parallel and to the left of the shower drain. Then it ties into the 3" line just downstream of the shower wye.

Depending on how much room there is on the 3" line between the WC and shower connections, it might be easier (less concrete to break) to add a 3" x 2" wye in between the two current connections to the 3" line, and to use that new wye for the shower drain. So the shower drain coming out of the trap would continue to the right a bit farther than currently and then turn at a 45 to the new wye. The existing 2" riser would remain, with the current combo at the bottom replaced with a LT90.

Cheers, Wayne

@wwhitney, I think your second suggestion would be easier to due to given the configuration. Here are some photos with more of the dirt and rocks pulled away.

https://imgur.com/gGUZfN7
https://imgur.com/wDGn0wx
https://imgur.com/5gPfpsE


So here was what I was looking at doing... Starting from the end of the shower drain P trap 90, I would eliminate the 45 bend going to the 2" riser. I would then do a LT90 instead of the combo Wye & 1/8 bend. Now with the LT90 in place that would serve as my laundry standpipe and sink drain. They would be downstream to the bathroom plumbing group.

Then starting from the shower drain male P trap, I would run a 2" in sloped line towards the 3" WC drain. I would then install a 3x3x2 combo wye & 1/8 bend.

Due to some clearance issues of the proposed shower pan, I will need to move the WC drain a few inches over and was going to use a 45 (1/8 bend) right after the combo Wye (closer to WC drain).

I also know the wye I have resting on there is not a 3x3x2. I didn't have that fitting on hand, so just wanted to get an idea of angles.

Is it possible to keep most of the current pipe I would still use, or would I need to fit together a completely new run?

Thanks again!

Nick

 

[wwhitney]

It sounds like what you are describing is what I suggested. But to be sure, I would need a floor plan showing the existing and proposed. If you are able to get an overhead photo showing the piping on both sides of the wall, you could just draw on that, one color to make the existing pipes clear (maybe dashed for pipes you will be removing), and another color for new pipes.

Cheers, Wayne