I am working on a fairly significant project (3 1/2 bathroom remodel).

I need to move my main sanitary stack. I've eliminated all of the fixtures and branches that tied into it.

All of my fixtures are vented individually. If I read the Illinois plumbing code correctly, I still need a main stack to my house that is at least 3" in diameter EVEN if I all of my fixtures are vented individually.

Am I reading the code correctly? I'm wondering why I need a separate main stack if all of individual branches are and fixtures are vented separately.

Thanks,

Steve