Moving tub drain - CI below slab

Our 1965 house has the original cast iron garden type tub in the guest bathroom. We want to put in a regular tub. I've attached a picture showing the current setup. From another plumbing job I believe the main line runs below the wall on the left hand side from front to back, with the septic tank at the back end. All fixtures in the house have a dedicated vent through the roof except for this tub and the shower in the master bath. Does that mean this tub is wet vented?

If so, can I move the drain as proposed? It would be ~18" shorter and need to move several inches to the front of the picture.

Would I use a no hub and then pvc to get to the correct location? That is how the plumbers put in the new pvc trap and riser in the master bath shower when I redid it.

I appreciate the help!

TJanak said:

Does that mean this tub is wet vented?

If so, can I move the drain as proposed? It would be ~18" shorter and need to move several inches to the front of the picture.
!

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It doesn't mean that at all., But on the other side of the coin, it could be wet vented, and if it is, the new location of your p-trap weir needs to be minimum 18" away from the "Wet Vent" .

If it would be a wet vent it still would be 18" away from the vent.

Any other potential problem with doing this? Just want to make sure before I destroy the tub because I doubt I can get it out of the room in one piece.

TJanak said:

If it would be a wet vent it still would be 18" away from the vent.

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The 18" minimum measurement is for a wet vent. It can be wet vented In most cases up to 5Ft away maximum, and in other cases 6Ft maximum away depending in what state you live in.

drain

Where does the 18" MINIMUM dimension come from? I have NEVER heard about that. Not having a vent through the roof means nothing as far as whether the tub and shower are vented. There are many ways to vent them inside the building, but they are not likely to be "wet vented". That is NOT a garden tub, it is an American Standard Neo-angle bathtub, which is heavy, but movable without destroying it once you get it turned up onto its apron. The "drain" is NOT where you show it. The actual connection as at the center of the tub below the overflow connection which makes it about 3'+ from the new location. I am concerned about the new drain location, however, because unless you are also redoing the lavatory, the tub and its "wall" are going to be too close to the cabinet to give you access into it. You might want to check into using a 4'6" tub to take up less space.

hj said:

Where does the 18" MINIMUM dimension come from?

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From My code book

HJ, the overflow is only about 6" to the right of the drain, along the back side of the tub. You can see part of it in the picture in my original post. But you are right I do not know where the trap, etc. is located beneath the tub. I took some pictures today over lunch and maybe they will help. This shows the overflow and pipe going to the drain which is only ~10" away.

I understand the reason for venting plumbing, just not all of the correct methods. I just wanted to be aware of any problems I may be creating by moving this drain.

I do plan on trying to remove the tub in one piece first, I think it will barely make it out the door and into the hallway when on its apron, not sure though.

We will be redoing the lavatory and counter and I am thinking of making the counter turn into to wall that will be at the front of the tub with a cabinet/shelf hanging on the wall in that small alcove. Didn't know they made a 4.5' tub.