Adding 1/2 bath to cast iron stack (rough in question)

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Darrell Woolaver

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Hi all, 93 year old 2 story house presumably with with original cast iron stack. I have lived in house 17+ years with no major issues.
The sewer pipe unfortunately exits the basement through the foundation about 2 feet off the floor instead of into the floor.

We would like to add a 1/2 bath either on 1st floor in an existing pantry room behind the kitchen (which does not currently have plumbing nor is there any plumbing in shared wall) or another thought is to add 1/2 bath in the basement using an upflush toilet like a Saniflo.

I have an open wall cavity I can run new vent pipe up into attic and tie into vent line/stack but I don't know the feasibly of tying into the sewer line for the new toilet drain. I don't want to get into replacing the stack. Based on pictures below can anyone recommend best method to tie into sewer line? I will be able to move washer/dryer and also remove the wall sheathing behind and shelf above for better access. If we can realistically do this at all I'm leaning toward the upflush unit option which I believe uses a 3/4" or 1" drain pipe instead of 3" or 4" standard toilet pipe. I do plan on pulling proper permits. The area in basement where 1/2 bath would go has little over 7' tall ceiling and a block window with an opening 1.5 sq/ft for ventilation which seems to be code requirements for the space (in addition to all the other plumbing/electrical stuff of course)

Side note: You will notice the bucket under the washer stand pipe that is overflowing from time to time which I also need to investigate. Not sure if there is partial blockage or if the stand pipe is not tall enough. It takes several months for the bucket to fill up.


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Still learning
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New York
How about removing the clean out and installing a combination wye and 1/8 bend and installing a new CO on the run of the wye

This way it discharges by gravity rather then relying on a pump
Hey, wait a minute.

This is awkward, but...

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