Kitchen/Laundry venting question
My kitchen sink and washer (in the basement) sewer drains connect in a closed system to a sewer pipe 50 feet away from the main stack (I think it is a second sewer line because it doesn't seem to enter the main stack). It is not vented and the kitchen sink bubbles and gurgles when the washer empties. In addition, when the sink drains I have concerns that it might empty into the washer if a large amount of water goes down the drain. I want to install a dishwasher (not present now) as well as a garbage disposal. I do not want to do this before I add a vent to this line. Do I have to run the vent up through the three floors of the house to the roof or can it be vented through the exterior wall?