Please review my plan for bath plumbing

[Bcarlson78248]

I'm renovating my basement bathroom & laundry and need to move all the fixtures around and replumb. I have the concrete out to expose the existing cast iron pipe, but would appreciate a quick review of my plan for the new plumbing. I have an existing 3" CI XH drain pipe that serves the current bath/utility, and a 2" CI vent that runs directly up to the attic and out the roof. For the combination washer/utility sink drain I already found several pictures on the forum that show how to plumb/vent that combination.

I've attached a drawing of my plans for the plumbing layout, and I also have a few specific questions.
1 - Can the 2" line to the bath sink also serve as a vent for the shower, and can the 2" line running to the washer also serve as the vent for the toilet? Or do I need more dedicated vent lines?
2 - I will use a fernco coupling to connect the new 3" toilet drain to the existing CI 3" CI XH pipe. Is there anything special I should know about that connection.
3 - The existing CI pipes seem to have some type of charcoal material underneath them, which may have been used to level them in the original installation. What material should I use under the new PVC pipes to ensure they stay in place as the new concrete is poured in?

Thanks for your help/suggestions.

Bruce

 

[Tom Sawyer]

No vents

 

[Sponsor]

 

[Bcarlson78248]

Maybe the diagram is not clear. The two green colored lines connect the top of the two 2" drain pipes into the blue colored vent that runs to the roof.

Since the 2" sink/washer drain joins the 3" line from the toilet just after the connection to the toilet, and the other 2" sink drain connects about 24" downstream of the shower drain, if I connect both of these lines together in the ceiling and connect to the existing vent to the roof, is that sufficient venting for the toilet and washer/sink drain?

Bruce

 

[FullySprinklered]

The washer can't share a vent, locally. Avoid flushing a toilet past a pipe of a smaller diameter; branch off the 3" toilet drain with a 3" wye, then branch out to the laundry tub and washer from another 3" wye, reducing to 2" at that fitting. Vent separately and bring the vents together up the wall or in the attic.

 

[Bcarlson78248]

I will try to paste in the diagram Terry has often used on the site, where a washer and utility sink share the same drain. That is the method I plan to use.

For the washer/sink drain into the 3" pipe - I know its not the best idea to flush a toilet past a smaller diameter pipe, but is that type of connection prohibited? After re-reading the requirements for venting, if I use this method I may need to add a vent on the toilet drain that is upstream of the point where I connect the drain for the sink/washer.

Bruce

 

[Bcarlson78248]

I have tried to improve my diagram so that you can get a better 3-D perspective.

My primary question is whether I have sufficient venting. Especially, do I need to add a dedicated vent for the toilet and use a separate drain line for the washer/sink combo in the utility room?

Thanks,

Bruce