Hello, I am installing a washing machine drain line using 2" ABS pipe. The drain line will be installed within a 5 foot horizontal run going into the main stack. Within 5 feet of the main stack, do I need a vent line? Thanks for the help.

Yes. You need a vent. As far as I know, you may not vent through a soil stack; rather you must have a vent that ties into the stack above all the fixtures draining into the stack.

Cheers,
Moishe

Yes. You need a vent. As far as I know, you may not vent through a soil stack; rather you must have a vent that ties into the stack above all the fixtures draining into the stack.

Cheers,
Moishe

Moshie was correct when he told you you couldn't vent back to the same soil stack you're discharging the washer into unless you revented back into the vent stack at least 6" above the flood rim of the highest fixture. However I've freehanded a drawing of a washer installation,( see image) You may install a AAV cheater vent in place of running a pipe to the roof . You may now place your washer as far away from the stack as you wish. Good luck, Tom