Some friends of mine are considering converting a closet into a full bath. (It's a pretty big closet.) What size pipe does the DWV vent have to be serving three fixtures, a toilet, tub and vanity sink? The reason I'm asking is, if he has to frame a 2X6 wet wall to accomodate pipe of over 2'' the tub won't fit without moving another wall. Moving the wall may be a budget buster as there are obstacles to construction there, i.e. central vac, receptacles and a/c-heat duct work. I told him I'd check with the forum members for advice. Thanks guys.