I am reworking my plumbing to a small bedroom ;changing it into a full bath. I am running a 3" vent thru the roof. Can i tie all the other vents into this one 3" vent before it exits the roof. All the revents will be on a 1/4" per foot grade to where they would tie into the 3" line before it exits the roof. Reason is so there won't be so many pipes protruding. Is this ok with plumbing code, thanks?