How can I tie a new sink drain into an existing shower drain? I have a stall shower that has been removed for replacement and woulde like to add a sink on the abutting wall. Can I tie the drains together?

Hey RNSOUSA...

Sure can! Just need to run the pipe from sink to the drain in floor. Just be sure to remove the shower ptrap before connecting the sink drain (could also connect to the toilet pipe, too... ;) ).

You will also need to install a minimum 1.5" vent for this new sink. Here, you will install pipe to sink and then run 1.5" vent up to another vent in this bathroom (connects to other vent(s) at 48" off finish floor) or another rvent upstairs.

If venting is a tremendous hardship then you may be able to install an AAV (air addmittance valve) instead. Here, you will install piping and ptrap to the new sink, but you will use a tee fitting under the sink so that you come off the top of the drain pipe where you install the AAV... see picture below. Be clear, however, that these vents must be accessible and that they can malfunction and need to replaced down the road (about $5.00).

These AAV vents may also be illegal in your area so you need to decide what to do here.

Let us know if you have more questions...

MARK