Moving Toilet - Existing Vent is offset from Stack

[mechmess]

I am in the process of renovating my bathroom, which will include moving the toilet 3' horizontally, and have uncovered a bit of a pickle.

The old toilet was sitting directly on top of the vertical stack with a sanitary tee used to offset the vent up through the wall. If I want to move the toilet 3' to the right of its old location, what is my best solution? The best I can come up with is to tee in the vent in the new lateral that I will extend for the toilet. However, in order to route this through the wall, I would have to downsize the vent from 3" to 2". Is that OK?

Any alternatives or criticism is welcomed!

 

[Reach4]

Maybe this?

PVC Long Sweep 1/4 Bend, Street

If cast iron, shielded coupler couples the spigot (same size as pipe) end of the PVC bend and the cut cast iron pipe.

 

[Sponsor]

 

[mechmess]

Maybe this?

PVC Long Sweep 1/4 Bend, Street

If cast iron, shielded coupler couples the spigot (same size as pipe) end of the PVC bend and the cut cast iron pipe.

Thanks for your reply! Maybe I'm not quite understanding you, but how would the 1/4 bend connect to the drain? The existing pipe leading into my wall is only the vent - the drain is down through the floor directly under the old toilet location.

 

[Reach4]

Thanks for your reply! Maybe I'm not quite understanding you, but how would the 1/4 bend connect to the drain? The existing pipe leading into my wall is only the vent - the drain is down through the floor directly under the old toilet location.

Oops... clearly I did not read properly.

Any chance you could bring a lavatory drain to join the toilet waste? That would constitute a wet vent, and you can go horizontal with those.

 

[mechmess]

Oops... clearly I did not read properly.

Any chance you could bring a lavatory drain to join the toilet waste? That would constitute a wet vent, and you can go horizontal with those.

There is a lav located right next to where the toilet will be that I could join in, however it currently has it's own vent. Is it not proper to run the existing vent in the wall, provided that I ensure it has 1/4" per foot slope?

I believe that the existing vertical vent functions as part of the vent system for a bathroom on the floor below, so I am a little apprehensive to eliminate it.

 

[Reach4]

There is a lav located right next to where the toilet will be that I could join in, however it currently has it's own vent. Is it not proper to run the existing vent in the wall, provided that I ensure it has 1/4" per foot slope?

The lavatory having its own vent, running 2 inch from there to the toilet line, is how the wet venting is done.

If you make a rough floor plan including the lavatory and obstacles to running pipe, somebody can probably suggest a plan.

 

[mechmess]

The lavatory having its own vent, running 2 inch from there to the toilet line, is how the wet venting is done.

If you make a rough floor plan including the lavatory and obstacles to running pipe, somebody can probably suggest a plan.

Thanks for all your help Reach!!! I've gone ahead and laid out the existing situation in the attached screenshots... Your idea for a wet vent for this bathroom seems like it would work well for this floor, but my biggest concern is that I think I need to maintain some sort of vent for the floor below, which this strange offset is currently (improperly it seems) providing.

The upstairs configuration is pretty spot on as I've peaked under the subfloor, but the basement is a best approximation as I'm not sure what is all below the concrete. This is the only vent stack leaving the roof besides a separate small one for the kitchen sink.

 

[mechmess]

OK, one more try. Can I wet vent the whole bathroom in the way I have laid out, regardless of the funny business that may or may-not be happening on the floor below?

I currently seem to have no issues with siphoning or poor drainage for the lower level fixtures. Granted, I do not want to make them any worse, but it seems as long as the upper floor is properly plumbed that I should be ok...

Please tell me where I’m wrong!

 

[James Henry]

Any fixture on the first floor must have its vent go through the roof or tie into another vent at least 42" above the finish floor on the second floor before it goes through the roof.