Adding Washer to Existing Kitchen Sink Drain

[Jfenn]

My girlfriend just moved into a basement apartment that does not have washer/dryer connections. The owner is amenable to adding them if it can be done.

There is a 1.5" drain that serves the kitchen sink going along the wall that would serve as the washer location. See photo. The run along this wall is 5'-1.5", with a drop of 2.75" (11" to 8.75").

My present proposed solution is to replace the 1.5" section along the wall with 2" section. Then add a 24" length of 2" standpipe to a 2" p-trap above the new 2" section and connect to 2" section after a trap arm length of at least 4". This will place the top of the stand pipe at around 42". (24" stand pipe + 6" for the p-trap plus 2" for drain connector plus 10" for the height of the existing drain line. The kitchen drain line will have a 1.5" to 2" adapter before the washer drain.

Please advise if my present proposed solution is possible given the current IRC code.

 

[Reach4]

Can you enter that cast iron with 3 inch? Let's see a sharp closeup of where the PVC meets the cast iron.

Under current IPC, the pipe that handles standpipe+something_else should be 3 inch. Not that 2 inch won't be up to the job in practice.

Had this been installed before some earlier date that I don't have for you, then the 2 inch would have been fine and grandfathered in.

 

[Sponsor]

 

[John Gayewski]

Agree, need better pic of cast iron connections there.

 

[Jeff H Young]

Normally a proper tee would be used plus you lost your main clean out when the PVC was added
. 1 1/2" definitely small beyond legal anywhere your code requires 3 inch mine requires only 2 inch .
I could understand not wanting to cut the stack Which I believe is 4 inch. So Id try to get at least a 3 inch wye right at the connection and run at least 2 inch for the wash machine and kitchen sink. Assuming you aren't governed by plumbing codes

 

[Jfenn]

I can put a 3" fitting into it. See attached.

 

[Reach4]

I can put a 3" fitting into it. See attached.

That would make everybody happy. Kitchen would have been vented already. Add an AAV for the new 2-inch standpipe.
Introduce the standpipe with a wye or combo (combination 45 and wye)

NIBCO 3 in. x 3 in. x 2 in. PVC DWV All Hub Long-Radius Combination Tee-Wye Fitting C4812LHD332 - The Home Depot

The NIBCO 3 in. x 3 in. x 2 in. PVC DWV long radius combination tee-wye is used in residential and commercial drain, waste and vent systems. The PVC DWV tee-wye features a long radius and a hub x hub x hub connection. The tee-wye allows for a connection to be made in continuous pipeline and...

www.homedepot.com

NIBCO 3 in. x 2 in. PVC DWV Spigot x Hub Flush Bushing C48012FHD32 - The Home Depot

The NIBCO 3 in. x 2 in. PVC DWV flush bushing is used in residential and commercial drain, waste and vent systems. The PVC DWV flush bushing features a spigot x hub connection and provides a means for

www.homedepot.com

 

[Jfenn]

That would make everybody happy. Kitchen would have been vented already. Add an AAV for the new 2-inch standpipe.
Introduce the standpipe with a wye or combo (combination 45 and wye)

My sincere thanks for your help. I apologize for my lack of knowledge. Are you recommending that the washer drain be fitted with an AAV after the p-trap?

I made a sketch of how I thought it should be constructed. I thought the open standpipe on the washer drain would provide adequate ventilation so I did not include an AAV in the sketch. See attached.

 

[Terry]

A washer standpipe needs a vent for the p-trap, or the trap will siphon dry, letting smelly sewer gas into the home.

 

[Reach4]

Nice drawing tho. And good on picking up on the 4-inch trap arm minimum bit.

I think the easiest is to have another 45 with a sanitary tee on top and the AAV at least 4 inches above the santee.

I looked at couple of places for 2x2x2 pvc santees and did not find. https://www.coburns.com/products/pl...09306-2-pvc-dwv-sch-40-sanitary-tee-hxhxh-400 shows it.

For easier parts availability, you could use a 3x3x2 sanitary tee, with different parts to go with it. https://www.homedepot.com/p/NIBCO-3...Hub-Sanitary-Tee-Fitting-C4811HD332/100342376

 

[Jeff H Young]

what we he use a 3x3x2 santee for? perhaps a combi