Trying to understand wet venting
I am starting to layout the DWV for a new bathroom we are planning. I have read the IRC 2005 code book and I am a little confused on venting a bathroom group.
Paraphrasing the code book it says that any fixtures in the bathroom group can be vented by the lav. It then describes the wet vent as the portion of the drain extending from the dry vent downstream to the waste stack.
This is the part that has me confused because the code book then shows examples of bathroom groups where various fixtures (bath or shower for instance) that are upstream of the lav. How are they vented?
Does the trap weir to vent distance still apply when the bathroom group is wet vented? Once again in the code book examples it would appear that some of the tub traps would exceed 3'6" allowed for a 1-1/2" fixture drain.