Hello all,

Disclaimer: I'm not a professional. I've reviewed the MN plumbing code to the best of my ability but I am far from certain that my plans are correct. If I have made an obvious mistakes, you have my apologies in advance.

I've been planning our basement finishing project for the past few months, and am ready to file for permits. I have some questions regarding my DWV layout.

So, what we have currently is a laundry/utility room. I've taken pictures of the room from the four corners to give perspective, and have photoshopped in some outlines as to where we want things to go. I also have the overhead view of the room in it's current state, what we envision the final state to be, and the all-important DWV view. I'm attaching the layout and DWV views, but all photos are available for viewing here

A few specific notes:

1. The kitchen/upstairs bath drain system was going to be replaced since I was already doing a ton of concrete work. There aren't any changes, per-se, just new pipe and cleanouts since the existing cleanouts are frozen up. It's more preventative maintenance than anything else...unless someone thinks it's a complete waste of time.

2. The existing 4" main stack reduces to a 2" pipe immediately above the main floor toilet connection, as seen in one of the pictures. I'm planning on ripping the entire stack out and going 4" straight up through the roof. I have access to the stack on the main floor wet wall through the back of a closet, and we have an open attic, thankfully.

3. If you have any feedback on the overall layout of the room, please feel free to comment.

My questions are:

1. the 2" drain that includes the whirlpool/tub and laundry will be 2" - I'd like to get that bumped to 4" prior to the toilet connection. How best to handle this?

2. Does my combined vent for the sink/whirlpool/laundry work? It would be 2" everywhere. I have an I-beam running at the top of the sink wall (right wall in the overhead view) so routing around that will be difficult...if I can "wrap around the corner" with the vent that would make life much easier.

3. The whirlpool vent, given that the unit will be probably 36" wide (and thus the drain will be at least 18" from the wall) requires me to route "backwards" to the wall to tie the vent in. Any better way of accomplishing this? I will have a similar problem with the toilet but that should be close enough to the wall to work.

4. For the main floor bath, can I use the same drain flows (shower combines with sink, then ties in with a wye below the toilet connection? I'd be reusing the existing vents, which I didn't draw on the DWV diagram.

Again, if I've made any idiot mistakes you have my apologies. Sorry for the information overload and number of questions. Thanks in advance for looking and for any feedback you can provide.

DWV diagram
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Current layout of the room
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Proposed layout of the room
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