Removing the stack and planning for the future

[Two60zCowboy]

I've lurked this forum for years. It has always been a go to for me and has been a resource, but now I'm going big....I have old cast iron still in place. The vent/The stack/The line to the street. It is all 4". 1933 is a date that I found under the cement utility sink. It still all works, but I just got a long 12" seam crack in a part of the horizontal in the vent line. I fixed it last week with JB water weld and before it dried, I decided that it is time to just replace everything. It's a small house / small job / everything is easy enough to get at (all down stairs/unfinished basement). This is small town Wyoming. No permit needed (Under $1000)/ the city will send "someone over" when it's done / IPC 2018 code. My plan is 4" ABS. Follow the same design / layout of the old pipe but then add a 4x4x2x2 at the vent line and a 4x4x2x2 on the stack line. Three of the 2x2's would be capped off for future use. The fourth - I would use for the washing machine drain.
I've looked at a lot of fancy modern day vent plumbing online and I don't see how my plumbing fits in to this. I have a vent. The vent is on the left side of all the drains, never had a problem with it. But I want to add a 4x4x2x2 into the vent line in case "some one" says the system isn't properly vented and for some future fixture. Is it allowed (IPC2018) to cap off unused vents and drains. I like code, and I like plumbing, I'm not trying any short cuts. This job is for fun.


I can draw the 4" house plumbing system as H_ just remove the left leg of the H and tie the _ to the right leg. That's my plumbing system.

 

[Terry]

Basically you have vents making their way to and through the roof, and you have drains making their way to the septic or sewer.
The vents break the siphon on the traps so that they retain a water seal to prevent air and gas from entering the home.
Reventing take place six inches above the flood level of the fixtures served. The sink and washer should have vented traps.

 

[Sponsor]

 

[Two60zCowboy]

Yikes!, I've seen that picture. It never made any sense until now - "Reventing take place six inches above the flood level of the fixtures served." That means I only have a main line vent. That's gonna take some fancy plumbing, but you made it perfectly clear what needs to be done.
Thank You , Sir

 

[Two60zCowboy]

Hmmm...That Picture. Those vents...
Disclaimer - I might have cabin fever!
I have continued to research. Seems that there are other theories about venting a plumbing system (other than IPC 2018 code), such as Combination waste and vent system. The theory of 4" into 2" into 1 1/2". I suppose, I could fill my bath tub, fill the bath sink, fill the kitchen sink, run the clothes washer through a washing machine clean cycle - wait for it to do the final drain, pull all the plugs at the same time and then flush the toilet. Put this ol' house at maximum drain capacity.
I guess I would look for the water to gurgle. If it gurgles, I have a venting problem.

Disclaimer 2 - I am not debating code. This is for fun. I like high performance and I like testing theory.

It would be the kitchen sink (1 1/2)/ the bath sink (1 1/2) / the bath tub (1 1/2). These three connect to a 2" horizontal that dumps into a 4" horizontal waste/vent system.

Anyone think this is a bad idea.