I'm trying to follow IPC code, but I'm not sure I have this right.
The 4" combo wye is below a WC and to be plugged upstream with a C/O. The 2" pipe is the tub trap arm connected to a 2" combo wye draining a Lav and venting through the roof. The 2" drain for the lav is the Wet Vent for the WC and the Tub.
a. Based on table 912.3 looks like my vent needs to be 3". Am I reading the code correctly, or will my layout work?
b. Can I connect the tub into the upstream side of the combo and call it a horizontal wet vent, or does it have to connect via a wye downstream of where the wet vent goes horizontal?
c. Any other issues here, or suggestions?