Hello all and thanks for reading. I installed a new bathroom and am now planning the DWV plumbing. I included an ISO drawing and a few views from a modeling software program I'm using.

I want to replace the original cast iron stack with PVC (from floor to closet flange). I'd keep the cast iron vent pipe and connect it to the new PVC using the proper rubber fitting. I figure replacing it would be the easiest option for what I want to do. I will then run a horizontal branch (3" dia) to the new bathroom. The WM (washing machine laundry tub) will connect to the top of that horizontal branch. I want to run that horizontal branch as close to the basement floor as possible (about 1' above it). Is that ok to do or is there some sort of code telling how high branches must be from the floor?

I also want to do a nice clean install and install the pipes of the new bathroom through the joists. The 2" pipe going to the shower will be parallel to the joists and I was going to run a wye off that, through 1 joist the run an elbow and parallel the joist to the lav. Is this good? I know I can only drill the outer third of the joist and there is a max dia hole per width of joist and I will follow those rules.

I attached a bunch of different views so hopefully this helps. Not in the views are the clean outs I'm putting at the base of the main stack (above the branch) and the base of the new vertical pipe going to the new bathroom. The new horizontal branch will against the wall. The main stack is about a foot from the basement wall. The new branch will come off that on a 45 degree (horizontal) angle toward the wall the I'll use another 45 elbow to run the branch against the wall. The washing machine wye fitting will be right off that 45 elbow (if that all makes sense.) The pictures don't show that.

Thanks everyone for your help!

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