Moving shower drain (extending) approx. 30" - Any considerations?

[jaysen]

PHOTOS:
http://imgur.com/a/W3IFu

Location: Southern California
Built: 2005

Wife and I were tired of our downstairs bathroom (guest) and decided to do something with it. We HATE, HATE, HATED the builder installed fiberglass so that was the first on our list to go. After demoing, I realized we had about 4' of void due to the stairs being just behind the bathroom. Our original plan was to keep the same footprint (36" x 36") but after some discussion, we decided to open it up a little.

We are doing a walk-in curbless design (zero entry). The shower head is now on the adjacent wall and will require us to move the drain, roughly 30" center to center. Up until now, I have done all the demo and framing work and if you consider PEX sharkbite plumbing, then some plumbing to date! The existing shower drain looks like it taps into the toilet pipe and not to the stack directly in front of it (see pics).

I will be finishing the shower in wedi board with their fundo pan for proper slope/drainage. With all that said, I am not real familiar with venting and its requirements. I read the UPC 906.1 regarding it, but I am slightly confused and looking to all of you for help.

So my question is this; Can I cut back about 3" before the existing P trap... add a 45 degree elbow, 25" (or so) of straight pipe and then the new p-trap ?

I can provide more photos or diagrams if needed. thanks!

 

[Jadnashua]

We'd need to know a bit more about how the drain is connected now...it should be vented before the toilet or you could have problems both functionally and meeting code. On a 2" line, before the line turns downwards, it must be vented within 5'...so, you may need to address that. If not vented properly, flushing the toilet can siphon the shower's p-trap and allow sewer gasses directly into the house.

As to extending the line...you need to move the p-trap to beneath the new drain location or you are likely to run into some nasty smell issues. The insides of the pipe can tend to accumulate a film of body oil, conditioners, hair, soap scum, etc, and without the trap being nearby, it can get pretty rank. Second consideration, moving another 30" away from the point where it connects to the main sewer also means another 5/8" rise in the pipe to maintain the minimum of 1/4"/foot slope on a drain of that size.

 

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[hj]

Who "looped" those lines to the washer box, and why the two tees? A professional would have put the valves into the top of the box and just offset to them.

 

[jaysen]

Who "looped" those lines to the washer box, and why the two tees? A professional would have put the valves into the top of the box and just offset to them.

Who, would be the builder - Pardee Homes (well, their subcontractor)

Yeah, im not sure this was done right...