Troubleshooting Main Drainpipe Leakage & Possible Washer Standpipe Design Issue(s)

[Calj]

I would like to get your recommendations on troubleshooting and fixing main drainpipe leakage and possible washer standpipe design issue(s).

Background:

One of our younger relatives remodeled our laundry room in our Salt Lake City, UT basement a couple of years ago and we have had some issues with our plumbing. About a year ago, we had flooding coming from behind the wall while the washer was running. Upon further inspection, the issue was that the standpipe was not glued into place at the base. I thought the problems were resolved but I have noticed some minor leaking along the baseboards. The standpipe spans the basement to the kitchen where the kitchen sink and dishwasher are connected. I am unsure if the main drainpipe is vented; I did not see a vent to the roof.

I cut the drywall open and have some concerns about the design and how it was put together. The issue appears to be sludge-like material seeping from where the 2” waste pipe connects into the 3” waste pipe near the base of the floor (see attached pictures). I am not sure if the issue is a result of the plumbing design, the quality of the workmanship (gluing/connection issues), if there is a blockage in the lines to the sewer, venting, or a combination of these issues.

Based on my research, the washing machine standpipe height (currently 9”) and p-trap distance from the ground (currently 36”) appear to be out of code. There is also a pipe that connects to the base of the 3” drainpipe (see pictures) that has been reconnected to the upper portion of the 2” drainpipe just below the piping to the washer; I believe this used to be a pipe that connected the to the old washer standpipe (before the remodel).

I have also included a diagram of the situation (see pictures).

I opened the drainpipe access and it appears to be clear (there is sludge on the backside of the cap). The other plumbing throughout the house appears to work without issue.

My current approach to fix this is to replace the 3” pipe just below drain cover and extend up into where the 2” pipe, get rid of the side pipe that starts & reconnects to the main drainpipe, and install the washer p-trap within 18” of the floor to the 3” pipe. I also plan to flush enzymes through the main drain pipe if there are blockages with the sewer line.

Thoughts?

 

[Diehard]

As far as that leak between the 2" and the 3". Chances are you had some partial blockage that was enough so when you had a high flow it backed up to that point or above and leaked out.
If the joint was made up properly(not sure what they ended up using there) it shouldn't have leaked even if it did back up to point above that point(to within reason).
They could have used something like these products to transition from the 2" to the 3" and perhaps they didn't have a tight fit to begin with.

https://www.lowes.com/pd/fernco-3-i...VFJSzCh3elgfREAQYAiABEgK81_D_BwE&gclsrc=aw.ds

https://www.homedepot.com/p/NIBCO-3...ERCH=REC-_-pipsem-_-100346732-_-100343802-_-N

Now the standpipe appears to have multiple problems.
1. Assuming it's not tied into that line up to the kitchen, it doesn't have a vent.

I'll be back!

 

[Diehard]

I'm back!
In addition to no vent, the standpipe drain line drops a substantial amount which could siphon the trap.
Also, when it finally does tie into the 3" drain line venting through that line is questionable due to (1) It wouldn't meet requirements for a wet vent. (2) We don't know if that drain line from the kitchen is vented.
Now there may be some codes that allow the elimination of at least one vent through the roof by using all AAV's(Air Admittance Valve's). Mine is not one of them.
If you don't have an vent through the roof then you would have to have an AAV to protect the traps in the kitchen as well as the bathroom.
Assuming you have vents elsewhere where they are required, you could add one for the washing machine once you got that piping squared away.
That 9" is required to be at least 18" min. to the weir of the trap. The trap could be as low as it takes to enter that that pipe you show 18" above the floor. I can't tell if all of that piping is in the wall but the new standpipe can be exposed with the trap, followed by a 4" min. distance to a tee for a vent with an AAV and then enter the wall to join up into that 3" line.
Something like this...

 

[Calj]

Thank you very much! Very helpful! Upon further inspection, the drainpipe does have a vent. Unfortunately, the vent comes out horizontally at the top of drainpipe under the kitchen sink and someone duct taped the end to close it off; probably because it smelled. It appears all the other plumbing in house is tied to a drain pipe that has proper venting through the roof so that is good. The standpipe end is relatively close to drainpipe so I may have to curve the pipe a little back from the ptrap.

Would you put aav on top of drainpipe under kitchen sink, between drainpipe and standpipe, or both?

Also would you connect standpipe line to the 2” part of drainpipe, 3” part, or it doesn’t matter as long as under the 18” from floor?

 

[Diehard]

Not sure what's going on at that sink. Is that duct taped pipe coming in from the wall coming off the top of the dropping drain pipe? If so then yes they must have had an AAV under the sink. So yes put an AAV as high as possible in the vertical, on that line.
Not sure what you mean by, "between drainpipe and standpipe, or both".

Don't think it matters on the standpipe. The 2" will be connected to the 3" as required, whether you use some of the existing 2" or not. It's a matter, I suppose, on the easiest way to do it. Is that a full 2" plugged cleanout at the end of that 2" line, that you might be able to connect to? Otherwise you may have to rip out that 3" san tee and fix that leak at the same time. Not sure if you have enough length of pipe, maybe below that cleanout to replace it with new, with couplings.
Maybe a real plumber will offer some suggestions.

 

[frodo]

you can not wet vent a fixture on anothe r floor. period,,no discussion

the 2''pvc into 3'' abs has been made not using the correct gue and primer

it is also illegal to connect abs and pvc together inside the house

Plumbing code specifically, does not allow commingling of abs & pvc pipe via a glue joint. Must be a mechanical joint (screwed adapters)or SS sleeved coupling (no hub band) with approved no hub adapters. Combination or multi purpose glues are not allowed.

the reason? IT LEAKS


all of that plumbing needs to be removed and replaced

 

[Diehard]

I think he ended up with what I was saying except not sure why the entire pipe up to the floor above would have to be removed and replaced.

 

[Calj]

Thank you for all the feedback. I was about to get started replacing everything from just below the clean-out coupler up through the standpipe. I also planned to extend the 3" pipe up while using the ABS cement for all the joints.

Then the plot thickens... upon further review I found another parallel drainpipe right next to this drainpipe (touching it hidden behind the drywall covering both pipes). The two drainpipes connect into the 3" drainpipe base. See first below diagram. I am curious as to your thoughts on how to approach it now.

The picture shows pre-remodel with the two pipes. I am not even sure why two pipes would even be needed other than there is a drain in the middle of laundry room.

I was thinking of adding another 3x2 Wye coupler above the tee coupler for the standpipe (see second diagram).

 

[frodo]

this appears to be a waste stack and a added ptrap wih a vent

 

[Calj]

I like that idea a lot. My only concern is I might not have enough room as I am constricted by the stud. I have 11" from stud to T coupler end and the p trap is 9.5" leaving me only 1.5" between at best. Thoughts?

 

[Diehard]

For my own understanding, why is the sketch on the left Wrong?


Forget it!
I'm not sure I even follow the total picture.

 

[frodo]

I like that idea a lot. My only concern is I might not have enough room as I am constricted by the stud. I have 11" from stud to T coupler end and the p trap is 9.5" leaving me only 1.5" between at best. Thoughts?

turn the trap so it is exposed behind the washer

 

[frodo]

For my own understanding, why is the sketch on the left Wrong?
View attachment 22125

Forget it!
I'm not sure I even follow the total picture.

read the code on stand pipe height AND the height of TRAP
the stand pipe was 9''


lt is all about the height of that stand pipe

 

[Diehard]

lt is all about the height of the stand pipe

But the diagrams show the vent line differently. I thought that's what you were referring to.

The 9" standpipe was acknowledged as being incorrect from the onset by the OP.

Sorry.

 

[frodo]

802.3.3 Standpipes

Standpipes shall be individually trapped. Standpipes shall extend not less than 18 inches (457 mm) but not greater than 42 inches (1066 mm) above the trap weir. Access shall be provided to standpipes and drains for rodding.

1002.1 Fixture Traps

Each plumbing fixture shall be separately trapped by a liquid-seal trap, except as otherwise permitted by this code. The vertical distance from the fixture outlet to the trap weir shall not exceed 24 inches (610 mm), and the horizontal distance shall not exceed 30 inches (610 mm) measured from the centerline of the fixture outlet to the centerline of the inlet of the trap. The height of a clothes washer standpipe above a trap shall conform to Section 802.3.3. A fixture shall not be double trapped.

 

[frodo]

But the diagrams show the vent line differently. I thought that's what you were referring to.

The 9" standpipe was acknowledged as being incorrect from the onset by the OP.

Sorry.

the height of the tee off the waste stack is making the stand pipe be 2 short [ min 18'']
THEREFORE the plumbing arrangement does not meet code

I know the OP said it was wrong, i drew the picture as a reference to show the diff between right and wrong

what is your deal?

 

[Diehard]

forget it!

 

[frodo]

turn the trap so it is exposed behind the washer

or
cut the stud out of the way, head the stud off

 

[frodo]

Not sure why you're quoting the code.
The 9" was an accepted violation. (Purpose for not being too short being primarily for splashing concerns.)

I am quoting the code because you said

""
For my own understanding, why is the sketch on the left Wrong?""

The code explains why it is wrong, are you clear as to why it is wrong now?

 

[Calj]

Thank you so much for all the feedback. Looking at diagrams online, it says standpipes should be 18-30" but I could really use a few more inches to keep the p trap line less than 18" to the floor (my washer box bottom is 46.5" from the floor). Can I go up to 42" on the standpipe as you stated with the code?