My plan is to install a sink and toilet down here (no shower or tub). Judging from this photo it looks like my basement rough in was tied into the house already. If that's true, then do I need to vent this sink and toilet drain?

If I do have to vent the sink drain, can I use an Air Admittance Valve (AAV) instead? Because I don't see anywhere I can tie into a vent line without breaking into the upstairs.

Hi RMS...

YUP! You definitely need to vent the sink as it acts as the vent for itself and the toilet. A 2" vent would be required by code...;) You would run this 2" vent upstairs and connect into a 2" or larger vent at a minimum of 42" off the finish floor or at any height off the floor in the attic. You could also penetrate the roof with this 2" vent...must be between 12" (warm climate) and 24" (cold climate) past the roof line.

If an AAV is allowed in your area then you can certainly install that for the vent. The AAV must remain accessible for the future because they do fail once inawhile and need to be replaced.

MARK

This job would never pass inspection in my area. My code forbids discharging a major fixture past a unvented minor one. And that exactly what you've done with your shower. The shower should have had its own vent or been tied back to the lavatory drain where it would have been wet vented. Also I would have lowered the entire group to eliminate the "dogleg" at the exit point.
Was this job permitted and inspected? Regards, Tom

Hi Tom:

RMS stated that he was only going to install the toilet and the sink and the pipes are already under concrete so I didn't want to bum him/her out too much.

Never mind the unvented tub/shower, heck, even the fitting for the lavatory/toilet vent is illegal... a sanitary tee fitting... :rolleyes: Further, is that pipe for the lavatory/toilet vent only 1.5", too (also incorrect...should be 2")?

NO WAY this job was inspected!

All that being said, RMS, my advice still stands... use the AAV or connect into a 2" vent upstairs.

Have a good day all!

MARK

Thanks for the help guys, truly appreciate it. With this being a basement bath I expect the drainage to be slower than those upstairs. Will a direct vent give me more drainage flow than an AAV or does it not really matter? Also, FYI: I'm in Dayton, OH and I assume the plumbing was inspected when the house was being built. However, because of work and school schedules I had a tough time getting out to see the construction on routine basis. The lavatory drain is 2"