Is it within code (UPC or Residential) to service and vent an air admitance valve (AAV) to the outside of house? I live in the area of Redmond, WA. The plumbing is on an external wall and first floor. It seems just as easy to vent externally behind a removable grill as it is inside. I think STUDOR vents are spec'd to be vented internally or externally if not exposed to weather elements.