no bath venting?

am trying to remodel a bath on an upper level, about 3' above lower level in older house. Problem is I see no signs of venting, or traps. the drains are in poured concrete slab. there is no signs of stacks on roof or through the walls. lower part has 2 baths both which seem to be correct, both with vent stacks.
I have all walls exposed from the inside and there are no vents going up. The drains all seem to go straight down about 36" before they elbow. so now i am trying to figure out what in the world they did here. I don't know how operational this was as to drain flow as it was not in working order when I bought the house.
so I guess my question is, is am I going to have to jackhammer down to add traps and ventlines or is there some kind of setup I don't know about?
I really don't smell sewer gases but I don't see a normal setup. any ideas? thanks

You are asking us to make an evaluation based on YOUR perception of the situation, which could be COMPLETELY ERRONEOUS. How were the drains installed BEFORE you cut the tops off of them? the traps and vent lines GO ABOVE the floors so if you jackhammer anything you are doing it wrong.

actually i haven't cut the tops off any drains, the shower was a cheap plastic prefab and when we took it up there was an 2" pipe sticking up about an inch below floor level.I thought there ought to be a trap , but there was no trap on the prefab either.
you can stick a stick into it and goes down about 3'.
but I also want to add a tub, hence the reason I was thinking I would have to cut down into the concrete,so to connect the drains, that is unless we can raise the tub abit. but I still don't see any venting at all in the walls or thru the roof. Is there any way they could have vented it that is not obvious? like I said I have all walls completely exposed so I know what is at least behind these walls and this bath is about 20 feet from closest stack vent which is in original part of the house

and oh yes, I totally agree that my perception of the situation most definitely could be COMPLETLEY ERRONEOUS. It would make this much easier if it is. but I did have a plumber here and he kind of scratched his head not quite sure of the situation since we can see no venting. It is definitely a bath a non professional plumbed, so any ideas you might have would be appreciated.
thanks

It really does no matter what was or is there.

You are doing a remodel and everything now has to be installed in a way that meets or exceeds current building and plumbing codes. When you are dealing with someone else's hack job, it's best to start from scratch.

The shower should have had a p-trap.
From what you describe, there may not be venting. Without being there, it would be hard for us to confirm.
Normally, a plumbing fixture is vented within

42" for 1.5" pipe
60" for 2.0" pipe
72" for 3.0" pipe.

A thirty inch tail piece for a shower is too long.

Just because the stick goes down 3' does NOT mean there is no trap there. It could just mean the trap was improperly installed. there is absolutely no way for us to comment on the venting without seeing SOMETHING.

As HJ states, it's pretty hard to give advice without seeing what you have. Since you seem to have a real cobbled up mess, it might be best to get a professional plumber who can do more than just scratch his head and confirm that you do have a mess. You really want to get this straighten out before closing up wall and floors, and for sure do not start busting concrete! If concrete has to be cut, let a professional concrete cutting company do it right. A couple of fees paid to professionals now can save you thousands later.

Thanks all, after reading one persons previous on here with about the same situation I had already decided it is more than we can do, so I will give a few calls around and see about getting someone out here. I appreciate the responses, would call you all if you weren't so far away. thanks again

I think you have made a very wise decision! Good luck on the project.