Can you vent a clothes washer drain from the second floor to the basement?
Posted by Chris Gronski on April 24, 19100 at 17:43:04:
I'm putting in a basement apartment for extra income but I don't want to give up my laundry room. I've been through every possible scenario and there is really only one place I can put the washer and dryer... where the hallway on my second floor opens to an 8 x 8 square. There are several nice things about this location it was kind of wasted space previously and now it will be put to good use, it is on an outside wall to the north so I can vent the dryer (its a row house attached on both sides so this is rarer than it sounds), and the West wall has a cavity behind it that I can eassily access to run the water supply and drain. I have to do some work on the West wall directly below this location anyway so I'll be removing all the drywall on the main floor making running that pipe that much easier. I'm sure 2" pipe wouldn't be a problem.

The difficulty is venting the washer drain. The main soil stack is on the East side of the house. I looked under the ceiling drywall from the bathroom vent and there is no easy access to the joists. I wanted to run between them since I know they run East - West. Even if I tore the celing down (which I don't really want to do anyway) there does not seem to be a clear path.

Its even unlikely that I could get up through the roof from the west side. The third floor was added about 20 years ago. The house is 100+ years old and has been through many renovations there are double floors, etc. in a lot of places. The cavity on the West wall appears to stop at the second floor celing.

What I'm condsidering is this... I'll start in the basement on the east side at the soil stack. run horizontally (at a slight incline of course) through the basement between the joists, then up the wall cavity to the second floor. On the second floor I put in my sanitary T. The T off goes to my trap and finally to a pipe for the washer to drain. The other part of the T continues upwards 6" or so hits a 45 ELL then a 90 ELL then anouther 45 ELL (sort of an inverted "V") and goes right back to the basement, across the joists and back to the plubing stack (above where the drain hits the stack of course). In some ways this is similar to venting an island counter sink.

Assuming I am comfortable with ABS spaghetti Will this work? My other alternative is venting out the wall but I've never seen a vent that terminated sideways...