I'm putting a kitchen sink next to an outside wall. The wall is 2x4 framing, and sits on a 2x10 rim joist. My question is, do I cut the hole for the drain through the wall cavity, or can I go through the floor, since it will all be enclosed anyway?

My concern is that the wall is too narrow for the drain (1.5 inches for rim joist from a 3.5 inch wall thickness)

Thanks,

Bob

Hey Bob,

You do realize that in addition to the drain the sink will have to be vented with a pipe that runs to the roof don't you? However, there's a way around that that will allow you to keep the drainage inside the house and still vent the sink.
OK, Here's how I would run your installation.
Sink drain to "P" trap, a upright tee directly after the trap with a AAV,( Air Admittance Vent, see image) installed in the upright branch of the tee, a turned down ellbo to take the drain through the floor to connect into the house drainage system. Good luck, tom

Thanks for the quick reply. I'll check with the inspector to see if AAV's are allowed locally. If they are, that'll definitely be what I would use for the vent. I wasn't as worried about running the vent up the outside wall, since there's no rim joist in the way at the top of the wall.

If I read your answer correctly, then I can run the drain through the floor, rather than having to take it back into the wall, correct?