Rough, plumbing, a bathroom edition

[Handy Joe]

Hi all, I’m trying to help a friend do a plumbing job adding a new bathroom addition that will back up to a kitchen. I will enclose a couple pictures..
The main question is, we are adding a laundry, washer machine drain on the second floor so we need to put a vent stack up on that wall which would be the south wall and everything needs to drain out the north wall.
We are tying the drain for the new addition into an old bathroom toilet that was plumbed 3 inches into a 4 inch main drain with vent stack right behind it.
The question is, how do I vent everything to tie in for the new washing machine drain?

Note: the original owner had put in a raised floor on a concrete basement slab that is up 9 inches off the floor I guess he didn’t want to bust out Concrete.

My drawings are not very good, but this is what I’m dealing with. Should I run a 3 inch main drain line all the way through the system up the vent stack and then tie the washing machine 2 inch line on the second floor, dropped down and pick up the shower 2 inch the toilet 3 inch and then a inch and a half sink vanity and then out to the drain.

 

[Jeff H Young]

Tie the 2 inch laundry room pipe into the 3 inch downstream of the toilet. BTW no images or drawings are showing up

 

[Sponsor]

 

[Handy Joe]

Here are the photos

Tie the 2 inch laundry room pipe into the 3 inch downstream of the toilet. BTW no images or drawings are showing up

 

[Jeff H Young]

Still dont see em ? maybe give it a few hours

 

[Ncizjp]

If you’re trying to tie a new laundry into an old setup, you've got to be careful. Running a 3-inch main drain line through the system and up the vent stack is definitely the way to go. Just make sure to tie in that 2-inch washing machine line correctly on the second floor and drop it down to connect with the shower and toilet.I had a buddy do something similar during a san diego bathroom remodel, and let me tell you, it was a headache. But with the right help, it turned out well. Don’t try to wing it if you’re unsure—get a pro who knows what they’re doing. Otherwise, you might end up with a bigger problem on your hands!