I am building a small bathroom on the first floor of my house. I need a vent but cannot access the main stack above the water line. I was thinking of going straight through the roof of the first floor (see diagram) with a 2" vent pipe. I dont want this vent to pass in front of the window so I was hopping I could terminate below it. I know the code does not allow that. So my other solution was to just get out of the roof and install a cheat valve. I cannot find anything describing that online so just wanted to see what you guys think about it.