I bought on older home and found the bath tub was raised up in the bathroom, and it sits over the stairwell. It was raised to give more head clearance for the stairs. I did some new wiring and tore out some of the drywall and saw that the tub was plumbed over to the main stack with no vent, about 10 feet. With the way it sits, there is no way to run a vent up into the attic or tie into another vent.
Since I can access the drain line under the tub which is kind of sandwiched between the basement ceiling and the bottom of the tub, (about a 1 foot high space) can I put in a check valve style vent in the drain line?
Actually, the tub drains fine, but I keep thinking this may be something that needs addressed.