faced vs unfaced vs encapsulated insulat

Where can I get good info on the issue of vapor barriers with insulation? I live in Northern California. With fiberglass batt insulation, I have always installed the vapor barrier towards the conditioned space ( walls, floor, and ceiling). But I have been advised to use unfaced batts in both floors and ceilings. Can I use encapsulated batts for the floors and ceilings? Thanks for any input.
Replies
This has been discussed quite a bit here--you could do a search for old discussions, but probably better would be to go to http://www.buildingscience.com. Sorry I don't know how to make a link to it.