Is this proposed re-plumb legal?
I want to add a utility sink in the garage, but do not have room to add a vent for it.
Can I convert the entire drain stack for the washer in to a waste/vent stack, thereby utilizing it for both services?
Critical distance for both sink and washing machine trap to vent will be met.
The new vent-stack would be an auxiliary vent tied into another going out the roof about 12 feet away.
The new vent-stack would be 2" and the old 1.5" would be abandoned.
Black indicates existing pipe, red is proposed new.
Live in Washington state.