Mike-- The washer is actually closest to the house trap, and the discharge line has its own vent. Also, I have only used the washer 4 or 5 times--I just moved in 1.5 weeks ago. Also, This morning, after using an upstairs toilet a few times and taking a 2nd floor shower, when I came down to the basement, the toilet was still full. And, I have done 2 loads of laundry today and the toilet is still full. Once again--baffled. As for the no hub vs PVC/ABS debate--a few years ago I was working as a CM for homebuilder in the suburbs of Chicago, and my plumber used PVC waste. There were countless times when the plumber missed a nail plate and the drywaller screwed right through the plate. Thats a pretty sh***y mistake. --Howie