When we bought our house the plumbing drains for a basement bathroom were roughed in but they did not install any vent lines for them.

We have the first floor plumbing draining into the main stack which drains down into the concrete of our basement and out to the street. The basement bathroom toilet/sink/shower rough in drains tie into that main drain underneath the concrete. They are all capped right now. To properly vent with PVC would be too much demo to the upstairs so we are planning on using Air admittance valves(AAV)(Studor vents). (I can draw a picture if my explanation makes sense)

To vent the sink drain I'm planning to install an AAV inside the vanity.

How do I properly use an AAV with the shower and toilet? For the shower/toilet I'm assuming bust up the concrete, tie into that drain after the P trap with pvc, and run it up into the unfinished area and install AAV's there? Will that work?

  • Check your local codes, some areas do not allow these. They are sometimes referred to by plumbers as "cheater valves", or "cheater vents".
    – Tester101
    Jan 6, 2012 at 18:02
  • They are allowed by our local codes.
    – Paul Lemke
    Jan 6, 2012 at 18:55
  • Code will likely also dictate where you can install the AAVs (height relative to drain, air flow, etc). My guess is that you'd put one AAV in the vanity for the sink, and use AAVs in unfinished space (perhaps on the other side of a wall) for the other fixtures. You may also be allowed to "wet vent" the toilet via the sink. If you're not sure, you can probably call up a local plumber and see if he'll discuss the design with you for a small fee. Jan 9, 2012 at 3:44
  • What distance is the toilet from the stack?
    – auujay
    Jan 16, 2012 at 22:43
  • About 4-5 ft from the stack.
    – Paul Lemke
    Jan 17, 2012 at 4:35

1 Answer 1


So for those out there looking for an answer here is what my plumber did:

The toilet, sink, and shower were all fairly close to each other (in my case about 6 ft). He installed one AAV inside the cabinet under the sink. That is the only AAV installed. He said it has now become a "wet vent" to the toilet and shower drain.


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