I want to replace a tub with a shower, and the location where I'd like to put the drain has a 2" drain pipe (for the clothes washing machine) that runs very close to where I want to put the drain. So I would like to essentially have the shower drain P-trap come down so close it could almost touch the washer drain line, then just after the P-trap I would need to make essentially a 180-degree curve to turn the line around and go back to the washer drain line where I would have to tie in with a wye curve. This is in a floor joist space, so I have limited room without cutting through more joists (which I would like to avoid if possible)

enter image description here In this rough drawing (a top view looking down) the green is the existing 2" drain pipe for the washer that I want to connect the new shower drain into, and the purple is the rough pipe location for the new shower drain I am asking about. The blue parts are floor joists. It isn't to scale--the curvy part would likely use all of the available space between the joists, but I hope it gets the point across--it would immediately curve after the p-trap.

Am I allowed (code) to have so many immediate curves in the horizontal portion of the shower drain? Once the line comes back up from the P-trap, the nearly-horizontal line will essentially make a 225 degree curve (180 degree plus 45 degree wye) to get to into the washer drain line pipe. Thanks.

  • Hello, and welcome to Home Improvement. It's a little hard to understand what you mean; would you add a diagram? Mar 28, 2020 at 16:43
  • I added a diagram
    – Shawn
    Mar 28, 2020 at 17:05
  • If you have a tub now, how is it connected to the drain?
    – Jeff Cates
    Mar 29, 2020 at 6:03
  • It has a separate drain line and vent that is to the right of the right-most joist in this picture. And it is a 1-1/2" drain all the way down the wall, so too expensive to replace that with a 2" shower drain line to pass inspection. But we wanted to center the shower drain if possible. Venting may be more difficult with this new drain. location.
    – Shawn
    Mar 29, 2020 at 19:51


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