Can (must) P-trap be directly underneath the drain in stand-up shower stall? I'm roughing in a 48"X36" one piece shower stall with a center drain. In the photo I've just got it dry fit. This is the way I "think" it's supposed to go? I can't imagine moving the P-trap any closer to the vent, as I'd have to use another 90. Or, asking another way, can I do it this way? Total distance is 24" to the vent, so I'm good there. A shower with other than a center drain is not an option, this is a stand up shower only, not a tub. enter image description here The way I envision this is I'll have about 4-6 inches coming out the trap (the "e" in pipe is level with top of crete), then the drain base glued on that. Yes I can easily slope to the vent, picture doesn't show it well. BTW the wye on the vent is already glued in (long time ago), and yes I plan on completing the vent with two couplings, vent is already plumbed to the main vent stack (not pictured) above, and yes, I plan on closing this back up with crete, then the shower stall on top of that. The clean-out in the photo is from the old laundry drain and is no longer connected to anything.

  • This should be fine. Remember not to slope too much from trap; slope from trap outlet to vent fitting inlet should be ≤ the trap arm diameter. Check local code. Jun 22, 2019 at 17:07
  • Far easier to clean and service if under the drain
    – spencer
    Jun 29, 2019 at 15:46

1 Answer 1


Looks good. You want the p trap where you have it, not back by the vent.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.