In my bathroom remodel, I have to run a drain from the tub, to shower, to building drain. It's a somewhat long run (maybe 7' tub to shower and about the same shower to building drain) but I have 14" I-joists underneath so there's plenty of room.
I had been thinking I should stay 1 1/2 all the way from tub to shower, but after reading a bit, it seems like increasing to 2" immediately after the tub (use a 2 X 1 1/2 X 1 1/2 wye to vent right at the tub and switch to 2) would actually be better for flow.
I also read a recommendation that the same logic applies for going to 3" after the shower, but the existing shower connects to the building drain with a 2" pipe, and I don't plan on replacing that, so will keep it at 2". Virginia follows IRC so the DFU for a 3 head shower and a tub is 5, which is OK in a 2" horizontal drain (as I understand things).
So, 2" all the way, or is there a reason to stay with 1 1/2?
Thanks,
Bruce
I had been thinking I should stay 1 1/2 all the way from tub to shower, but after reading a bit, it seems like increasing to 2" immediately after the tub (use a 2 X 1 1/2 X 1 1/2 wye to vent right at the tub and switch to 2) would actually be better for flow.
I also read a recommendation that the same logic applies for going to 3" after the shower, but the existing shower connects to the building drain with a 2" pipe, and I don't plan on replacing that, so will keep it at 2". Virginia follows IRC so the DFU for a 3 head shower and a tub is 5, which is OK in a 2" horizontal drain (as I understand things).
So, 2" all the way, or is there a reason to stay with 1 1/2?
Thanks,
Bruce
