I'm thinking about adding a bathtub to my half bathroom. It has also been suggested that I should replace my existing cast iron pipe with pvc and bring it up to code. Attached is a pic of the existing layout with the new bathtub added and vent.
I would like some opinions of the existing layout, since the house was build in the 60's. We are under the 2006 INTERNATIONAL PLUMBING CODE. I mostly concern about the venting. Does the 2nd toilet need to be vented? I'm only seeing two vents on the roof. The 1 1/2 from the existing tub, and the 3" vent. I don't think one of the sinks (on the right) is vented. Thanks