I am installing a bathroom in a basement, single vanity, water closet, bath/shower. The drains were roughed in by the builder, poured concrete floor, and everything seems to be in the appropriate position. My concern is about adequate venting. There is a single two inch vent through the roof for the entire horse, two full baths, one powder room, laundry and kitchen. AAV's were installed during construction for the laundry and powder room. Do I need to install another AAV for the basement bath, and in what configuration? Are there concerns about sewer gas when using AAV's? I haven't had problems with the two that are currently installed.

It will be OK, but check to see if the plumber preroughed a vent for the basement.