Have a kitchen sink drain and small leak at the last L where it comes out the wall. The line in the wall is 1-1/4” copper and runs about 3 ft horizontal to the vent stack. Built about 1950.

Drain line in the crawl space has already had the copper drain replaced with 1 -1/2” PVC

Plan A was to cut open the back of 2 cabinets to replace that 3 ft section with pvc to the vent stack. Guess would have to piece together a few short pieces to fit in between the studs.

Plan B may be less work. And l would lower the drain a little so could add a garbage disposal. The line going in the wall now was a little too high to install one before.

But with this plan I would just cut open the sink cabinet back. And have a Tee. The top of the tee would tie into the old copper line for a vent.

Then drill a 1-1/2” hole thru the bottom wall plate. Then connect the bottom of the tee to the pvc drain line in the crawl space.



Is there any problem with either plan?

Thanks for any suggestions.

cap or plug the old 1 1/4 copper line.
tie in down below and put the tee as you described but put an AAV in the top of the tee.

Thanks for the reply.

Would the AAV be fine if I put in the wall. Or do I have redo and have the drain go thru bottom of cabinet?

AAV needs to be accessable. fine to drop straight thru cabinet. put a cleanout at the tie in point.

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