Hi, this vent question is one I'm on here looking for. Is there any reason a guy couldn't go 2" vents throughout (say, an addition) where there are 2 bathrooms (shower, lav, WC each) and a new laundry room with laundry tub. Eventually the 2" vents tie into the 3" stack. But my real question is that all over I see 1 1/2" venting referenced. Is it a preference, or material cost, or does it have to do with airflow physics? Can venting be too big?
When I got my inspection prior to cementing the floor in, the plumbing inspector made me switch from 4" drains to 3". My three boys duke footballs, I wanted 4" - he made it sound like I was doing it wrong. Long story, but I'm still pissed. So I guess that's my real question - can venting be too big?