I'm helping a friend install a sink in a workshop that was added onto his house. A previous owner installed a water line and a drain by boring through what appears to be the rim joist of the original house into the workshop but they did not vent it. I am reusing the holes they bored and want to vent the drain properly. My original plan was to install an AAV in the wall above the drain but after removing some of the stucco, it appears there is a stud directly above the drain pipe. The stud cavity to the right does not have enough room to fit the AAV box I picked out. I opened the stud cavity to the left and found that the drain goes through the end of the rim joist and has a sizeable amount of sill plate and framing above it. I am worried about notching/drilling through this part of the framing to accommodate a vent pipe.
What should I do? As far as I can tell, my options are:
- Notch/drill through the sill plate and remaining part of the rim joist to install the vent pipe/AAV + box in the left stud cavity.
- Install the AAV in front of the wall. Is this even legal?
- Install the AAV in the crawlspace behind the wall. This would almost certainly be at a height below the P-trap its venting and several feet away. Would this still be effective?
Do I have any other options?