Wall placement around shower drain hole

Hi all,

I am finishing my basement and adding a bathroom. When the house was build, the builder placed sink, toilet, and shower drains into the cement floor. The shower floor drain is in a square hole about 15"x15". There is simply a 2" PVC pipe sticking in from the side of the hole (capped). I will be hiring a plumber to do all the connection work with the shower. However, I want to frame my walls around the future enclosure now. The problem is, I don't know what to use as a reference for these walls. I have the dimensions of my shower unit which are based off its drain.

Will the drain in my cement floor end up being placed in teh center of the 15x15 square hole? Should I assume it will end up some distance away from teh 2" pipe?

Also, I do not see any vent associated with any of the floor drains? The only reasonable place to connect a vent would be to the 2" pipe for the sink since this sticks up about 24 inches. Is this normal or should I plan to add a vent to the shower drain somehow? Again, this is only to figure out how to place my stud walls.

Thanks!

I'd dig down in that hole a little to see if there is a trap installed. If there is, then the pipe would be exctly centered around your shower pan. My unprofessional opinion.

My unprofessional opinion is that the location of the drain is adjustable. That's why they left the 15x15 opening.

John's right.
The 15"x15" block out is used for the p-trap connection.
Since the location needs to be exact, the trap is installed by the plumber that is setting the pan.
And of course, you won't know the exact center until the walls are framed for it.

Thanks

Thanks for your help. THe hole is open and unfileld, definetely no P-Trap installed yet. I will build the walls so that the center is at least a 6" arc away from the pipe that comes in from the side to allow space for the P-Trap and some adjustment (or I may just buy one at HD and fit it on there with no glue for the time being).