basement bathroom retrofit - venting questions

Hello all,

Our house is located in Kansas City, MO, if that helps. Built in 64, all cast piping currently. All the cast iron will be completely replaced with PVC.

I am in the process of finishing our basement bathroom out - when the house was built, there were rough-ins for a sink, shower, and toilet, but the piping has corroded badly, and the layout does not allow for us to have our laundry down there as well.

I have created a 3D schematic of my intended layout. The main stack is in the corner of the room. Most of the plumbing is fairly straightforward, but I have a few questions:

1. the shower drain ties into the 4" pipe running between the toilet and the stack. will this work?

2. the shower vent - I have this tying into the upstairs sink/shower drain as a wet vent - I do not think this will work, but do not know of another way to vent the lower shower. Please advise.

3. the laundry drain/vent - I wanted to have a small utility sink/floor drain sitting next to the washer - I was unsure of how to tie this all together - I would much prefer a floor drain tied into the laundry drain - please advise on best way to do this. also , i'm unsure if the venting i have drawn will work - I would tie into the upstairs shower vent if needed, as it will be directly above where the washer sits.

Perspective 1
Perspective 2

Thanks a ton for any input you can provide - I hate to sound like a newb, but I've been researching this off and on for the past six months and we are finally getting to the stage where we want to get some pipe laid.

Deb

This is not going to work. You pretty much need a revamp of the whole basement plumbing. The 4" stack which carries waste from an upper floor cannot be used for the vent for the downstairs fixtures. Each fixture needs to be vented. I would try to tie these downstair vents together. You can tie in to another vent 6" above the highest fixture that vent serves or run the vent out by itself. The shower and the washer cannot be connected to the portion of pipe that runs between the toilet and its vent, called a trap arm.
You may want to consider hiring a plumber to lay this out for you. It is tough when we cannot see what you have and try to give you a layout. Also, codes vary from place to place.
Deb
The Pipewench

Deb,

first off, many thanks for the input - after realizing that the original layout would not work, I have moved the toilet to a different wall - that also solves the issue with venting the lower sink.

My question now is how will I tie a 4" toilet trap arm into the 4" main stack, while also tying in a 3" or 4" drain line for the two sinks and the shower - I have tried to rough outline of what I need - basically, I think it will be a three way waste tee (the red arrow). Or, I could tie the trap arm into a 4" drain that will run into the main stack, if needs be, making it a standard tee. please advise on either.

sketch

again, sorry for all the questions, but i cannot get a hold of my local inspectors office to get any assistance from them - nobody ever picks up the line, and i've been trying every day for a week!

thanks again

vents

I do not know about your inspectors but the ones I have dealt with are not in the design business. If they give you advice but you misinterpret it, which is not impossible, you will blame them when it is turned down. You need a local plumber. All your first drawing did was create a new drain path for the upstairs fixtures. Your latest one also has deficiencies but it is getting better.