Good info covering different climate zones. This is not so much as how to build the structure, but how to design a vented or unvented roof and different designs for insulation type and placement.
http://www.buildingscience.com/documents/reports/rr-0404-roof-design (http://www.buildingscience.com/documents/reports/rr-0404-roof-design)
Once the page is opened the document can be saved as a PDF file.
A companion article...
BSD-102: Understanding Attic Ventilation
Again both vented and unvented considerations
Understanding Attic Ventilation (http://understanding%20attic%20ventilation)
And another...
BSD-149: Unvented Roof Assemblies for All Climates
http://www.buildingscience.com/documents/digests/bsd-149-unvented-roof-assemblies-for-all-climates/?searchterm=roof%20design (http://www.buildingscience.com/documents/digests/bsd-149-unvented-roof-assemblies-for-all-climates/?searchterm=roof%20design)