I'm trying to vent my shower and came up with this mock-up. This will be between the floor joists separating the first and second floors. The 3" straight waste line on the right is coming from the second floor bathroom group and is already vented. The shower will also be on the second floor but will drain into the 3" drain here. The 90 w/heel will then turn down vertically into a wet wall on the first floor. Two questions. I'm a little shy of joist depth to be able to stack that wye/1/8 vertical to accept the line from the shower p-trap. I would be ok to roll that wye as long as I don't go beyond 45 degrees correct? #2... am I really venting the shower If I take a vent off the top of that 90 w/heel and go up through the roof (I have a wall I can pass it through above there) or does the vent have to come off of the trap arm between the p-trap and where it connects to the existing drain shown (which will be miniscule in length plus be underneath the shower pan so I couldn't go vertical from there)?