This free PDF article (from the WA state Energy Code Builder's Field Guide) and shows how to get the best performance out of your insulation.
http://tinyurl.com/ddgd6
This is a good sized PDF and does not tell you it is downloading - be patient while it does. You can then save it to your own computer or print it out.
(http://img526.imageshack.us/img526/8008/floorinsul8ey.png)
See the posting to "Builders Guide" for a link to the other chapters in the Field Guide.