finishing loft attic over garage...

[supadave]

My garage looks pretty much like the one I've attached...
I want to insulate and finish just the attic over the garage but am not sure where to install the vapor barrier on the floor since the sub floor is already laid up there, would you just put it over top of the sub floor and seal it up with the v/b on the walls? And then if I ever insulate the garage, would I need v/b on that side also?

Thanks.

[little dude]

A vapor barrier is typically placed on the heated side of an insulated space. This is where many improperly install faced insulation batts in floors.