A question for plumbers?
Answers:
they both go to the same place. You will need a trap from the sink and one for the shower to prevent sewer gas from coming into your home.
Other answers:
yes it is just be sure to have a "P" trap connected to both drains [ they usually are] it is best to use 2" pipe for the work. anything same will back up on to the floor
yes it is just be sure to have a "P" trap connected to both drains [ they usually are] it is best to use 2" pipe for the work. anything same will back up on to the floor
There are local codes. Best to get a Plumbing 1-2-3 book to learn the basics.
I am assuming that you are not suggesting that the wash basin actually drain into the floor of the shower. Rather, the wash basin drains into PCV pipe (with the appropriate trap) and then proceed from there into PCV pipe that may indeed be connected to the same PCV output line as the shower (after its respective trap). Sure, no problem. Maintain proper pitches and ventilation per the Plumbing 1-2-3 book and have at it !