Toilets, Sinks, Showers, Tubs and Disposals - Revamping 1st floor drainage

:coffee: :wall: I have some BIG problems here. First of all My bathroom shower stall stinks like crap . I am assuming that the drum trap is syphoning out under the shower.?. But aside from that I just want to replace it all the [I]right way. What I have now is a 2 inch line and huge drum trap under the kitchen sink it is a double sink that when you try to drain one side it all comes up on the other side, then drains really slow sometimes backing up into my shower. That line is tapped into via a wye by the whole bathroom consisting of a 1 and 1/2 inch line going to another wye branching to my sink and a drum trap connected to my shower stall. (also no venting anywhere so far) The 2 inch main line continues for another 10 feet to the 4 inch soil line. I bout a power snake and snaked from the shower trap to the soil line...no glogs. But if I drain the kitchen sink with my shower drum trap opened the sink drains fine out the trap. Confusing yes? Any way I just want to replace all of it and put the proper traps I just need to find out the right way and if it should be pvc or copper? Oh yeah, I can solder. Thanks in advance for any help I can get. Shawn Correia

I would run all the piping in PVC, get rid of the drum traps all together and somehow get those two fixtures vented.

You can tie those two vents together as one above 42", from there continue in 1.5" to catch an already existing vent as long as it is above the last set of fixtures it serves. Meaning, 42" above the floor of the 2nd/3rd floor.