Have a question regarding a DWV system a plumber installed in a new build for me which utilizes a wet vent. Apologies for the crude drawing which does not accurately show length, but schematically it is correct. Key information:

1) PVC DWV System on 2nd story and spans 2 rooms. Bathroom and Utility Room. Below is a garage.
2) 3" main stack line (vertical)
3) WC drain line is 3" from flange to stack, all other drain lines 2"
4) SH = Shower, Lav = Lavatory, WM = Washing machine box
5) All fixtures in bathroom, with exception of WM which is in utility room
6) WM is dry vented with 1 1/2" vent line and 2" drain line.
7) SH, Lav and WC are horizontally wet vented (2" line) with vertical dry vent at LV that is 2"

I believe the system has two code violations, labeled with a 1 and a 2 on schematic:

Violation #1: For the short portion (<12 inches) of the wet vent that is downstream of the LAV, SH, and WM but upstream of the toilet (labeled with a 1 on diagram), the total DFU is 5 (Lav = 1, SH =2, WM = 2). 5DFU for a wet vent requires > 2" pipe, but plumber used 2". (I am not sure if 2.5" or 3" is required).

Violation #2: The WM, which is dry vented (required as it is separate room from bathroom group), should tie into the drain system downstream of the wet vent. As the schematic shows, the current design has it tied into the wet vent portion of the DWV system.

I would appreciate it if someone could confirm if my assessment is correct and the system does have 2 code violations, or if this design is ok.


Thanks

the toilet, shower and lav are OK. i don't care for the big change of direction the shower drain has but it was probably unavoidable.
the washer drain has to go between the toilet vent and the stack.
so #1 is OK.
#2 is as you thought done wrong.

Thanks. Agree that #1 is OK once #2 is corrected. My only point was that even if the WM could tie into drain there, the pipe would no longer be sized correctly for wet venting due to 5DFU.

Corrected the schematic to show the offset between stack (in wall) and WC.




A few additional questions...


1) Does the horizontal wet vent need to be in the same plane? I ask because the the wye that connects the toilet to the lav/shower portion of the wet vent is turned up ~30 degrees. Most wet vent descriptions online show a single horizontal drain line being fed by branch drain lines, all in same plane. Is this allowed?








2) The space is tight to get the WM downstream of WC. This is how the WC line is plumbed now. The wye to the left is part of the wet vent. Toilet is straight up. Can't fit another wye fitting between the vertical stack and the 90 bend that is there now.






I have thought about other layouts and vent options.

(1) Dry venting the toilet, but can't meet the code that requires vent to be vertical until 6" above flood rim level. Need to run horizontal to get to wall.

(2) Thought of adding a dry vent to the top of the stack for WC. Not sure that would meet code for venting WC given the WC vent would not technically be on the drain branch.

(3) Update layout to run a true horizontal drain line from stack towards WM (perpendicular to wall) and then connect Lav, shower, Toilet, WM to this new arm. Given WM and shower drain lines have to cross will be challenging, and would also have to direct WC drain away from stack for a short run to make enough room to stick a wye between WC and stack.

Any guidance much appreciated.

.
rolling the "Y" like the plumber did is the preferred way to do it. perfectly fine.
I would run the shower into the end of the "Y" where the washer is now going.

I can't tell but is there any way to get the laundry drain into the vertical stack?
it looks like where the double plate is cut that you can enlarge that cut ( or drill a 2 1/2 inch hole next to it)and run the 2 inch laundry drain down and into a 3 x 2 "Y" in the horizontal stack. then individually vent the laundry up above.

just to clarify about wet venting.
I don't know where you got your info about 4 DFU's on a wet vent. remember, the 2 inch is also venting the toilet. so, the 2 inch is venting all 3 fixtures. my code says that a bathroom group on the same floor can be vented thru a single 2 inch pipe.

all in all it appears the job was well done. a couple of little mix-ups but very professional.

Not enough space to get by the truss or avoid the water lines to 2nd floor.



As far as the 4DFU limit for 2" pipe on wet vent, perhaps I am misreading the code. Here is a snapshot from IPC



The way I interpreted that size of the wet vent is to be "based on the fixture unit discharge to the wet vent" is that I looked at my schematic drawing and determined the DFU at each point along the wet vent. Let's ignore the washing machine in my schematic for now as it should not have been connected to the wet vent. Just downstream of the wye for the shower, the wet vent sees 3DFU (2 for shower and 1 for lav). 2 inch pipe is fine. At the water closet wye (next downstream wye), the water discharged from the water closet doesn't flow through the wet vent and is not counted against the 4DFU limit. For UPC, there is a requirement that WC has to be downstream of other wet vent drain connections which is why a 2" pipe on bathroom group with a lav and shower can work.

Here is a pic from one of the code summary books which also shows something similar.





As far as the quality of the job, the plumber has always done good work in the past. But, in this case he disagreed that the washing machine hookup to the wet vent was a code violation. Interestingly, the inspector did not catch it either. Further, we have had 4-5 leaky fittings. Removed fittings have shown the pipe was not inserted fully into the fitting. Not sure if this is atypical, but I assume it doesn't help.




Still not leak free.

I don't like that diagram from your code book.
unless unavoidable, I never vent out the back of a 'Y'.
I always (when possible) vent out the branch of a 'Y' with the branch rolled up.
you code diagram doesn't show sizes either.
according to the written parts of your code, that vent would have to be 3 inch.
yours is fine with 2 inch.
apparently the inspector and the plumber followed your code picture with the washer draining where the tub is drawn.
as for leaks..
I have had joints that for one reason or another did not fully insert when glued. never had a leak even under a 5 PSI air test.
the only time I have had a leak was when I was running out of glue and did not apply enough. :<(

For the code book pic, the pipe sizing could be 2 inches until shower, at which point the DFU would be > 4 and would need to be sized up.

Here is another schematic showing DFU.




For my setup, I think there are two possible layout solutions.

(1) Insert a combo 3x3x2 after the first 90 from the vertical stack. The fitting is ~ 1 inch longer than the space I have between the flanges of the 2 90's in the pic and would make the insertion of the 3" WC drain pipe more difficult as it will be offset slightly.



(2) Replace the 2nd 90 (horizontal to horizontal) in the pic with a 3x3x3 combo fitting. The wye leg would serve the WC, and the "through" leg would be reduced down to 2" for the washing machine drain. The washing machine would then be draining downstream of the Wet Vent.

Any issues with option 2? Any concerns with the solids getting hung up with that fitting? If not, it is the easiest solution to implement. I can also re-route the shower drain so that it is connected where current WM is, as you suggested.


Thanks for the advice..

#2 seems to be acceptable.
not great but acceptable.
how about a third option?
cut a 3 x 3 x 2 san tee into the vertical stack a couple of feet below the double plate. face the side to the right, drill a hole thru the stud and run a new 2 inch into the stud bay to the right and up thru the double plate and pick up the laundry.
P/S, yes, san tees are allowed on a vertical stack.
you will not have to mess with any of the long sweep 90's up above.
simply remove the laundry drain and drop it down into a san tee. then switch the shower drain to the current laundry location.

Maybe. Tight space between the 3inch drain line and the water lines running horizontally behind in the picture. Likely have to 45 right after the top plate. I would not go over past the truss on the right as then I run into even more obstructions with the wet vent to the lab and not keen to run the plumbing through the cripple studs over the door.



Why did you not like option#2? there is a long sweep 90 there now, does a combo have more restrictions than that?

you will only be drilling one stud and then turning the pipe upwards.
remember, you are seeing this up close while I am viewing pictures on a computer.
so what looks do-able and easy to me may in fact be ridiculously difficult.
(and vice-versa) :>

It will be tight but I will see if it can work. Just to be clear, you are suggesting a san-tee, short pipe through stud, and then a 90degree fitting to vertical. Needs to be a tight 90 to get vertical in time to clear the truss. Correct?

Back to my earlier question, what is the concern with Option#2 (replacing 90 with a combo for WC)? Just curious as to why that is less preferred.

Thanks

you said something about replacing a long sweep 90 with a combo fitting. you then mentioned the space available was a little shy of what you needed and assembly would be difficult and a pipe would have to be run at an a slight angle to make it work.
i'm paraphrasing but that is my impression of your situation.
so to me, running the laundry down into the stack makes more sense.
if you feel your option is easier then by all means do it.
it will work and be problem free.

Ah ok. That was for option#1 where I would stick a combo between the two existing 90's. Space was too tight to fit the combo in this option. Option 2 was to simply replace the 2nd 90 with a combo wye.

Thanks