I'm working on finishing the attic in my folks' house, basically from scratch, and I'm going to be putting up insulation soon.  I understand that if insulation is going to be put up against the roof, insulation baffles need to be put in to maintain the gap for airflow across the roof to the soffit.  They already had trusses put up in the attic from adding a shed dormer, so the ceiling is going to be flat along the trusses, and they had planned on running insulation flat along the trusses, as opposed to against the roof.  My questions:

1.  Do baffles still need to be put in to maintain proper airflow, even if there isn't insulation up tight against the interior of the roof?

2.  Is insulating flat above the future ceiling (flat along the trusses) going to be less efficient than if the insulation ran along the roof?

3.  Is the proper answer here to get both (insulate above the ceiling and against the roof)?

I'm torn between thinking that the insulation against the ceiling is going to prevent as much of the heat from flowing up out of the actual room, and thinking that having a big space of cold air between the ceiling and the roof is going to make heating less efficient.

Thanks!

If they never plan on using attic space as storage, then just insulate at the ceiling level.  Isluating at the rook is ok, but an air gap is a good option abd will let the roof "breath" and last longer.  But using the roof as the upper insulation level you're just added that much more volume you need to heat.  Ok I guess if you have the capacity and want the storage area if any to be somewhat conditioned.

Insulation is pretty cheap, adding more never hurts.

Edited:  Misunderstood what you said.

I'm looking at insulating the attic above my garage and have found some pretty good videos on Youtube.  Here's one that may answer your question, but if not there's dozens more on Youtube.

http://www.youtube.com/watch?v=5DX25Vz2jDc&feature=related

As for me, I'm still trying to decide if I need to add a vapor barrier or not.