I can't believe this is happening, but it seems my newly acquired foreclosure property the previous owner had done unpermitted renovations on, had put in a shower with no trap underneath it.

I am 99% sure.

Obviously this needs to be addressed, and the slab floor opened up. The question is where to make the cut and how big a hole to cut.

Due to the layout of the shower, and the shower having a half wall and a bench that's lined with granite on the inside, I am wondering if it's possible to leave the shower floor alone, and open the floor up outside the shower instead?

Here are a few pictures of the bathroom.







and a close up shot of the drain.



If I were to open up the floor, say a 24"x24" square hole, right outside the shower, between the toilet and the vanity, can I excavate over to the shower drain and plumb a trap under?

If I break up the shower floor, it would cut open the shower pan liner, which means ripping out all the tiles on the shower floor, and up the wall for about 18" or so, and the granite curb and bench. If I break outside, I need to only replace the tiles on the floor.

But there is another reason. I was thinking if they didn't even put a trap in, what else did they do in this bathroom DWV wise? Did they vent everything correctly? Did they use a santee to connect horizontal pipes etc?

Here is a layout of the bathroom, but also showing where the cleanout is on the west side exiting the house.

Also there is a 3" CI stack on the west wall of the bathroom, in line with the COs outside. So what I am thinking is the mainline for the upstream bathrooms, laundry room, kitchen etc...runs through here, right under the floor outside of the shower, and opening a hole there, has the best chance of seeing how everything in this bathroom ties in.





Looking down on the shower drain it heads east. So it must be making a 180 degree turn since the main line runs west.

I am thinking of hiring a camera inspection to go down the toilet drain as well as the shower drain, but not sure that would tell me anything useful...

I can't believe someone would do this. This is plumbing 101 right? How can someone not know to put in a trap?

Sum, running traps are not allowed(the trap needs to be below the drain). As you mentioned, what about venting? I think running a camera would be a good thing, to help see what's not visible and how to proceed.

steve, I don't mean to suggest installing a running trap. I mean the trap will be under the drain. What I meant to ask is if it's possible if someone laying on the floor with their hands reached into the shower drain area, not being able to see, can install a trap under there? Because if I cut a hole outside the shower and excavate, that would be what's required.

I remember some old stuff called drum traps that are away from the drain.

Can I do one here?

i'd just put a running trap.

The easy answer is "NO". You would need a fairly large hole, not 2 x 2, and a "tunnel", in order to work on it. But, if they did not know they needed a "P" trap, what makes you think they installed a membrane. Often when they use the blue plastic for the membrane they run it across the drain then cut the opening after clamping the top and making the test, in which case you can usually see the edges of the membrane, which you cannot with your drain.

Would a drum trap be better?

hj there is a membrane. Now I don't know if it's installed correctly.

I opened a wall in an adjacent room and I can see and feel a piece of liner folding up about 10" or so up the wall.



I myself would have gone up 18" at least and used something to fold it straight up and neat, but...

I don't want to rip up the whole bathroom so I am needing some brainstorm ideas.

There are a lot of unknowns. No trap. Is the shower vented? How is everything connected, I have already corrected the lav drain that has no p-trap, it was a piece of flex duct twisted up. Today I found more horror.

A "drum trap" IF you could find one does NOT fit in to a horizontal line. The inlet is at least 4" lower than the outlet.

Is there a way to cut the hole in the shower to install the trap, and afterwards still be able to not having to redo the membrane in the walls?

For example if I make a clean cut through, excavate down to install a trap. Once done, I backfill soil and compact. Then I pour to mend the original concrete slab.

Now once I have done that, there is the preslope layer which the membrane sits on. Down here I have seen people use mortar but many use sand. If its mortar I can chisel by hand carefully all around to create some space below the cut edge of the existing membrane, if its sand its easier. Then I just cut a new piece of membrane slightly larger than the hole and tuck that under the existing membrane, and glue them together.

Will that work?

Sum, that will work. Hopefully there is a preslope under the membrane....