Rerouting vent for Pedestal Sink Installation

[Giblet]

Hi all, I am replacing the existing sink vanity with a new pedestal sink and ran into a bit of a problem. When I removed the drywall behind the vanity (major overhaul :)) I noticed that the existing p-trap dumped into a sanitary tee that vented straight up. Unfortunately, this will conflict with the 2x10 backing I need for the pedestal sink (2x4 walls won't allow both :(). The existing vent system looked like this ('O' marks the spot of the p-trap, 'I's mark the stud locations):

The p-trap waste flows directly into the floor.

I want to rework the venting to the following configuration:

The main stack is less than 3' away so it isn't far but my concern is with the actual p-trap connection. I need to put the blocking above the p-trap do I don't really have room for a full revent above the trap adapter. Must the trap adapter be vented above?

P.S. I apologize for the "drawings"; they looked better before spaces were removed. I am attempting to publish a hand drawn version to link to or can PM anyone.

[Giblet]

Well, the more I read and think about this the more I know that I had better make the room for a full revent scenario. So I will be dropping in a sanitary tee for the p-trap and then running up a couple of inches from that and then taking the vent back through the stud to the vent that joins the main stack to complete the circuit.

[RioHyde]

It looks to me like you're wanting to go horizontal with your vent. You can do this, but not until you are 6" above the flood level rim of the pedestal lav you're putting in. You might try notching the back of the 2X10 around the existing vent leaving the "face" of the backing in place. Thing to remember if this works though is when you mount the bracket(s), know exactly where that vent is so as not to put a screw through it.

[Terry]

If you go up a few inches, then you can use "waste" fittings to move the vent over. Something like a long turn 90 el would do.

You could also use 45% bends to move it over.