I will appreciate your comments on a workaround I am considering for waste water for a second floor shower. The tub I am replacing drained into one of those lead toilet flanges that will be history and there is no other available option for waste water just below the second floor.

This creates a water drainage dilema requiring a dedicated drainage pipe to the basement. What I want to avoid is cutting into any studs [A] or having to raise the shower pan above the bathroom floor [B] to run the pipe horizontally above the floor to a suitable location for the vertical pipe. A or B would put me in a good position to tap into an existing waste pipe in the basement from the kitchen.

One radical solution not requiring A or B would be to run the pipe along the stud [2x8Ē actual dimensions, instead of perpendicular in the A and B options above] to the opposite wall [12 feet] where I have a clear easy open shot to the basement inside an interior wall. However, in this scenario I would have to drain the pipe into the basement wash basin that the clothes washer drains into. There is no living space in the basement and I have no intention of adding any in the basement of a 100 year old house. The wash basin is hooked into the soil pipe tied into the city sewage system so no problem with the ultimate destination of the waste water.

Although I donít see the wash basin ever overflowing, if it did the basement floor is sloped toward a floor drain with trap that drains into the same soil pipe, so there is a back-up plan. The drain is about 30 feet away from the wash basin at the front of the house. Nothing is left on the floor.

I wouldnít have to worry about sewer gas, but would have a trap directly under the pan as usual and a second one at the drainage point above the wash basin to close the system. Even shower pipes can smell.

Does this violate code? More important, what issues should I be concerned with as far as functionality? I could go 2 inch pipe all the way, but would like to convert to 1.5 inch at the vertical since this pipe would have no other fixtures draining into it.

The only problem I see is proper drainage since there would be no sewer gas to worry about? There would be room to put one of those air admittance valves at the vertical, do I really need it? Are there other methods to improve drainage? If the trap below the pan does siphon, I wouldnít be risking sewer gas.

This workaround would make a fairly difficult project very easy and eliminate the A and B problems noted above.

I know itís not the ideal situation. I expect to be in the house another 20-30 years, thatís why Iím going with a shower versus a tub, so nobody else will have to live with my workaround in the near future. When Iím gone they can do another remodel is my point of view.

Thank you in advance for your comments and suggestions.