Tub to shower. Ideas on how to fix.... this

[rowdy235]

Hey guys! Hope all is well and everybody is staying safe.

I'm coming down the home stretch (or so I thought) of a bathroom remodel that is over budget and behind schedule, lol. The last major project was to replace the tub with a shower, being as its such a small space. Initially my plan was just to tie the shower drain into the existing tub drain, but then I discovered the shower requires a 2" drain and the tub only has a 1.5". Fortunately my main stack exits just outside the bathroom. I went under the house yesterday to see what I was dealing with and was a little suprised with what I found, see attached picture.

Basically my house has 5 total drains- the laundry room is at the far end of the house and has a AAV, the drain line runs from there to the kitchen sink which also has an AAV (both were at some point before I came into the picture converted from S-traps). This line connects to the back side of the 3"(?) ABS pipe in the photo. The bathroom sink also has an AAV and connects as shown below. The tub doesn't appear to have any vent but is likely close enough to the main stack. The toilet appears to be the only part of the system connected to the original cast iron plumbing.

Just outside the wall there is a 4" main stack which runs to my septic tank. My main question is- how would you go about replacing this? I am likely going to call in a pro, but wanted to get some ideas. My thought was rip out all the ABS and do a dual 2" wye, one side running to the shower and one side running to another wye where the bathroom sink can tie in, and then tie in the existing drain from laundry/kitchen sink to that. Obviously would keep a cleanout on the end like there is now. Thoughts?

Also, would the shower need an AAV (or if not required would it improve its draining?) I guesstimate the shower drain to be about 4' or so away from the main stack.

 

[James Henry]

looks rough. the tub is probably wet vented by the lav, if that was the intention the lav drain should have been 2". I can't see the whole scenario but it looks like a complete redo.

 

[Sponsor]

 

[rowdy235]

Not sure if that was meant to be a wet vent as there is no vent at the lav (originally an s trap now an aav/ p trap)

Any ideas on venting the new shower without running a vent through the roof?

 

[rowdy235]

Here is a shot of the outside if it helps

 

[Terry]

Venting the shower by the lav, it would come off the lav line horizontally with a wye or combo fitting.
Normally it would be 2" on the lav wet portion and reduce on the venting for the lav above the sink p-trap.
You could run 2" on the lav in the crawl, using a 2" long sweep 90 that is reduced to 1.5" as it goes vertical for the sink drain. That's the best I can think of without opening the wall above. There should be breathing room in the 2" horizontal for venting the shower.

 

[rowdy235]

Thanks Terry, that actually sounds like it would be fairly simple. I have good access under the lav and should probably replace that pipe anyway (currently goes from ABS under sink to galvanized back to ABS).

Would the recommendation be to go 2” all the way to the San-tee for the lav p-trap? Can be 1.5” above that? Also would the vent being an AAV affect it?

Thanks guys for all the help, love this site more every day.

 

[Terry]

2" up to the 2" x 1.5" x 1.5" santee with 1.5" for the trap arm and 1.5 for the vent.
An AAV would work for that if it's not already vented.

 

[rowdy235]

Thanks everybody for the input!

A couple follow up questions,

1. I know there is a max length for the trap arm (60” on a 2”?), would this be measured up to the horizontal wye or combo since that is technically where the vent starts (even though it’s horizontal)?

2. In the first picture I posted you can see where the tub/lav tie into the main drain. In order to avoid having to tear all this out (eventually I plan to but not right now), do you think it would be feasible to cut off the end of the fitting (and the reducer), and use a fernco to attach a new fitting? I was thinking a 3” 45* with a reducer to 2” in the end followed by a long sweep 90 going toward the lav.

Thanks again!