Laundry Room - Washer drain and vent

[michaelt31]

Hi, I am in the process of planning a remodel of my laundry room. Currently the water for the washer is supplied from a tee under the sink and the washer drains directly into the sink. I would like to replace the tub sink with a cabinet/countertop/sink and install a washing machine outlet box in the wall.

My question is about how to connect the drain pipe and vent for the outlet box in the wall. I have a concrete crawl space below the laundry room, but the wall behind the washer sits directly above a floor joist. It may be possible, but is definitely difficult to run the drain pipe down to the crawl space. This is also presumably why the original plumber ran the sink drain through the wall to the left of the sink, rather than behind the sink. Can I run the drain pipe in the wall, then pop out inside the proposed cabinet and connect to a wye at the existing drain (see attached photo)? And if I do so is the vent pipe at the existing drain adequate? Or does the sink and washer need separate vents?

Hopefully I explained this in enough detail and thanks for your help!

 

[CT18]

My code in Detroit area is washer needs to connect to a separate stack if no laundry sink. I know Chicago code is as strict but they do have there own unique rules. You may want to contact local Jurisdiction. I would venture to say that line in the wall is not big enough for a stand pipe. The drain for the sink can be smaller as the sink will hold water before it goes down the drain. My code is 2" to the stand pipe and tie into 3" stack

 

[michaelt31]

Thanks for the response. I did not consider the drain pipe size. I just checked, the 1.5" sink drain connects to a 2" drain pipe via a 2"x 1.5" x ? tee (I am not sure if the vent is a 1.5" or 2" pipe). That 2" pipe runs for about 4 feet before connecting into a 3" main drain stack.

If I upgraded the tee from 1.5" to 2" would that be enough drain capacity for the sink and washer then? If so, then would I be able to connect the sink and washer into that 2" pipe with a wye? Sorry for the crude drawing, but something like the attached.

 

[MicEd69]

Here's what IPC allows, but I'm not sure Chicago will allow it. The picture is from 2018, but it is still in the current 2021 IPC.



The vent pipe can be 1 1/2" in most codes, but again, I'm not sure in Chicago.

Here are some more dimensions that must be adhered to for the washer standpipe.



And if Chicago doesn't allow what I've shown above, the sink drain needs to be attached to the vertical drain in the wall with its own sanitary tee. I would move the washer sanitary tee as low as possible meeting the above dimension restrictions and put the sink sanitary tee directly above it so I could get the maximum height for the washing machine standpipe. The washing machine standpipe will be wet vented through just a short section of vertical pipe.

 

[michaelt31]

Thanks so much for your help. I will double check with my local jurisdiction, but I should be able to make that work.