Underslab plumbing mock-up

[Gundraw]

It is time to get my sewer and drain lines plumbed in under my garage/workshop. I started a thread some time ago about this subject (https://terrylove.com/forums/index.php?threads/2-story-dwv-rough-layout.99294/) and @wwhitney helped get this scheme together:

After doing some redesign and finding a little more room, I figured the best/simplest layout may be something like this:

Do the extra risers simplify the design or make it better? I also figured that using the wye for the WC allowed the inline port to serve as a place for a vent as well as for a tee and plug for cleanout.

Here is the fittings I was going to use under the 6" wall.

Do all these look correct? The risers are what Menards calls a "Long Turn Wye" which I figured was comparable to a combo wye.

Just wanted a double check before this gets glued up and buried.

 

[wwhitney]

I marked up your drawing below with a green line segment (replacing a black segment) and a red line segment (which was missing from your drawing).

Based on your fitting line up, the red line segment is intended to be a dry vent for the WC. But horizontal dry vents are prohibited below an elevation of 6" above the fixture flood rim, e.g. below the slab.

If you delete the red and green segments, you have your first layout, just with an offset in the lower story dry vent. So you can implement your second drawing on that basis. But you could also omit most of the green segment, just enough to bring a cleanout up to an accessible location.

I'm not too knowledgeable about cleanout rules and best practices.

Oh, and yes, long turn wye = combo wye, those are the correct style of fitting. Although for Riser 1 and Riser 2 you could use a 3x3x2 reducing combo. Or possibly get rid of the vent riser/cleanout and keep Riser 1 as a 3" combo, with a 3" cleanout above the slab and below the san-tee for the lav.

Cheers, Wayne

 

[Sponsor]

 

[Gundraw]

Hey @wwhitney , Thanks yet again!

So I read over your email and suppose I wanted to paraphrase to make sure I have the details right:

#1, using the "vent riser" as I have it drawn violates code because it is a dry vent and a portion of the vent (even a small portion) goes horizontal before going vertical. Thinking about it, that kind of makes sense. I figured having a cleanout at the end-of-the-line was nice insurance. Maybe a stupid question, but if I were to run the Green line partially up the wall, cap it, and install a cleanout, can it be used at a later date as a wet vent/drain for a upstairs? An upstairs drain cannot be a wet vent for the downstairs.

#2, I agree that if you remove the red and green lines, you largely have the old layout. The only difference is now I have a riser from the main 3" horizontal line for that second utility sink. If that is superior than sharing the upstairs drain for that sink?

 

[wwhitney]

On #2, six of one, half a dozen of the other.

On the OP, the little red segment is the only problem. Can you just eliminate it? I.e. in your fitting layout, change the wye to a 45, and add a combo between the 45 and Riser 1 for the vent and cleanout. Or if space requires it, turn the closet elbow and change the 45 to a 90.

On the other hand, there's no particular upside to dry venting the WC. So Riser 1 could both be the lavatory drain, the WC wet vent, and get a cleanout tee in the wall.

Cheers, Wayne

 

[Jeff H Young]

I think this came up befor on another thread but the end of line cleanout is fine its just that when you connect it to the vent system it suddenly becomes an illegal vent even though that vent isnt needed I belive it would still be concidered a horrizontal dry vent less than 6 inches above flood level and prohibited.

 

[Gundraw]

Well, the day has come where I need to get putting all of this together. Here is what I came up with for a dry fit:

(images on ibb as I cannot get them to upload right now).

Sewer-Layout hosted at ImgBB

Image Sewer-Layout in Gundraw's images album

ibb.co

Here is the floorplan layout.

Sewer-Drawing hosted at ImgBB

Image Sewer-Drawing in Gundraw's images album

ibb.co

Couple questions:

1. Do all of these fittings look appropriate?
2. I decided to include the cleanout, just tuck it behind the wall as a "just in case". However, I was wondering if it is possible to use this as another drain line later down the road? I am using a LT elbow if that makes a difference.

 

[Jeff H Young]

1yes 2 yes

 

[wwhitney]

1) Sure. If I understand correctly, from left to right on the straight run is 3" cleanout, WC dry vent, utility sink drain, and lav drain (or maybe the last two are vice versa). If so, then the last three could be 2" lines, e.g. 3x3x2 combos. But if you prefer to use 3" stub-ups, that's fine. [Actually I think they could all be 1-1/2" lines, certainly the dry vent and the lav, but there's something to be said for keeping everything under slab at least 2".]

2) Maybe. The WC is supposed to be vented before or as the it joins another drain. So if the cleanout becomes another drain, it would now be wet venting the WC, and your dry vent connection would be superfluous. And the WC can only be wet vented via another a bathroom fixture on the same floor level as the WC. So i the future you could change the cleanout to a lav drain, wet venting the WC, and then that would free up your dry vent and lav connections for other uses. [In practice with the 3" dry vent shortly after the wye where the cleanout and WC join, I expect it would function fine with an arbitrary drain where the cleanout is, but it wouldn't satisfy the IPC.]

Cheers, Wayne

 

[Jeff H Young]

good call wayne . the clean out was legal but adding drains from above later wouldnt be right.

 

[Gundraw]

Interesting points. I suppose I added the third riser for any future plumbing additions that may happen on the second story (lets say, utility sink or something of the like. Unfortunately, the orientation of that cleanout is exactly wrong for where the lavatory would drain (other side of toilet). Is there a simple (simpler) solution that you guys see that would give me some flexibility down the road?

 

[wwhitney]

What's the order from left to right, cleanout, dry vent, lavatory, utility sink, or are the last two swapped? Is that order within the wall flexible or fixed?

Cheers, Wayne

 

[Gundraw]

Wayne,
As the floor plan sits, it seems that the most convenient plumbing would go (using the mock-up picture):

Cleanout - WC wye - Dry Vent - Kitchen Sink (double or triple) - Lavatory

I could also plumb it as shown in your first response (Message #2) minus the green line of course.
I am really flexible with the number of stubs, just wanted to fit it all in the 6" wall as shown in the floor plan snippet. If there is a better solution for future expansion, I am all ears.

I appreciate the insight.

 

[wwhitney]

Various options (upstream end to downstream order):

Cleanout - WC wye - Lavatory (wet vents WC) - Future expansion/Kitchen Sink in either order
WC elbow - Lavatory (with cleanout and wet vents WC) - Future expansion/Kitchen Sink in either order
Cleanout - WC wye - WC dry vent - Future expansion/Lavatory/Kitchen Sink in any order
WC elbow - WC dry vent and cleanout - Future expansion/Lavatory/Kitchen Sink in any order

Probably others I've not enumerated. But the key point is that any fixtures from outside the bathroom (the kitchen sink or the future expansion) join downstream of the WC's vent (be that a dry vent, or the lavatory functioning as a wet vent). This requirement could also be achieved by splitting the 3" horizontal drain somewhere, so you have two parallel segments, either side by side or possibly one on top of the other.

Cheers, Wayne

 

[Jeff H Young]

Might not be following wayne but its possible to branch off riser 2 or 3 from photo in post number 1 for an addition.
The section above the cleanout marked vent riser is un needed though its a nice way to vent there technicaly is no reason to put a vent on a cleanout what needs adressing is how and where you would like to get a future stub from? or just deal with all that later and put no thought now I dont recomend figuring it out later. theoreticaly riser 3 might take care of future as well?

 

[Gundraw]

Points are well taken - I think i understand the basic holdup:

The vent for the downstairs WC either has to be a dry vent, or be wet vented via the first floor lavatory (not kitchen sink, etc). So if I could accomplish that. It really leaves the other two drops open for whatever I want (without the upstairs bathroom sharing the same riser as the downstairs kitchen sink).

Jeff, you are getting close, I have an upstairs area, but I am not really sure what is going to happen and when with respect to plumbing. I'm trying to keep a blank canvas in case we find a need. At a minimum, I would assume at some point down the road, the 2nd story will at least get a full bath, hence the original drawings. Also know that the way I am handling the area above these stubs, is I will have plenty of space to run drain pipes to other areas of the building.

I would be comfortable saying that at most, the second story would see 2 full bathrooms. It seems like an additional riser between studs, downstream of the first floor WC would allow me to simply copy and paste the same upstairs bathroom drain design a second time? Something like this perhaps:

From my research, it seems that all of this together is still suitable for a 3" main line. know that I will be switching to a 4" outside of the foundation.

 

[Jeff H Young]

ok well the bottom drawing post #15 Id just stay clear of dumping drainage down the cleanout and the next downstream fitting because that one should be the vent for w/c no problem with having 3 full baths on 3 inch

 

[Gundraw]

Alright, so to not miss any details, here would be the solution right (added kitchen and lavatory sink drain lines)?

 

[Jeff H Young]

that works and the underground is super easy. I dont see a reason for 2 risers a foot apart for upstairs only bringing it up because I dont see the need for it.

 

[Gundraw]

Jeff, perhaps my rationale for the two risers was simply so each bathroom could have its own branch down to the trunk, then I could plumb both bathrooms using the example that Terry used to post all the time.

I am guessing based on your comment that I could easily combine both upstairs bathrooms into one 3" branch?

 

[Jeff H Young]

Its possible that 2 stacks next to each other would be very convieniant but not knowing your layout of framing and plumbing for future its hard to assume it would be beneficial because its uncommon