Bathroom sink to shower drain options?

[Whitehorse2865]

Hi experts. This one is like a riddle. Trying to add a shower to a powder room in a townhouse. The current setup has a sink and a toilet on opposite walls. The floor is reinforced concrete and the sink and toilet drains run thru the floor and into the underground parkade and then off to sewer land. The plan is to keep the toilet put, install a mini sink on the sidewall, and then install a shower where the sink currently sits. Was planning to build a subfloor with 2x6 under the shower to accommodate a trap and utilize the existing vented 2" sink drain. QUESTION: Best plan of attack to plumb in the sink drain? Somehow tie into the shower drain or would I need to drill another drain down thru the concrete floor into the underground parkade and tie into the main 4" line? Other options? Cheers.

 

[Tuttles Revenge]

If the drain to the sink is an adequately sized minimum 2" drain, then you could create a branch from it to serve both the elevated shower and the sink. Both fixtures would need to separately vented and co-joined again once above the flood level of the sink.