This may be code/region dependent, but I was wondering if there was a maximum length/distance (logically or otherwise) for a bathroom DWV line. I'm looking to add a half storey to the house, and where I want to locate my new master bathroom would cause some semi-significant demo work in a fairly new kitchen underneath to put in a DWV in the wall. On the other hand, I have a fairly innocuous area that I can run it at the front of the house, but it would have a 40-50 foot run from the bathroom to the stack in the front of the house. Given a 1/4"/foot slope, I figure I would need nearly a foot of drop from the bathroom to the vertical stack.

Is a 50 foot run considered bad practice if the slope is maintained throughout? Is there a minimum size that I have to run given the distance? If I need 45 to make a couple of bends, is that an issue? From what I understand, minimum size for bathroom drain in 3"; would I need to go 4"?