I'm remodeling my attic and I'm trying to design the DWV system right now. The attic is unfinished space.
I'm going to have two sinks, a toilet, and a freestanding tub (probably a cast iron tub or a lighter version of the same). I was going to run the drain lines from the two sinks together, meet up with the tub drain line, then hook up with the toilet line (3") as it drops verticall in a wall on the floor below this bathroom.
I'm going to use Y or T/Y combos to tie the lines together and to tie into the main stack in the basement. I was planning to run a vent line vertically in the wall behind each sink and I guess run it inside the wall all the way around the bathroom so that I can create a vent line behind the toilet as well.
I'm unsure how to vent the tub as there is no wall behind where the drain will be. Windows will be there. Should I just go for an AAV? They are allowed by code in my area? Should I just use AARV's all the way? I could put one inside the vanity of each sink fixture and have easy access to it and save a lot of time. Then maybe I can just run a vent line up from the toilet through the roof.
And maybe someone can give me an idea for venting the tub. I've drawn up some plans, but I'm not a great artist and considering how many different angles you need to see to make sense of this, I don't think I'll post it.
Anyone have a photo of how bathroom DWV lines are planned in a similar layout?
do you think tubs need venting close to their p-traps? How far away can a vent be, for a 1.5" pipe? If the drain line is sloped at 1/4" per foot, I think you can safely vent into it 4 or 5 feet away. From what I know or remember.
What say the plumbers?