On the right in the photo is the cut out in the floor to tie into a shower drain. You can see they have capped off the 1.5 inch line beneath the slab. To the left of that is the toilet flange and of course the drain is hidden under the slab. Behind the toilet flange is a 2 inch pipe emerging from the floor which is reduced to 1.5 inch diameter pipe as it rises from the floor. The sink will be located to the left of the toilet.
My question is, where is the correct spot to tie in the sink drain? Can I tie into the 1.5 inch vertical pipe? Or do I have to tie in low to the 2 inch diameter pipe?
I will save my questions about how to raise the toilet flange to accommodate my insulated subfloor for another day. :-). Any help or suggestions are greatly appreciated.