Garages and Carports - insulating an attached garage with truss attic

I'd like to insulate an attached garage so that the truss attic remains available for storage. The garage is completely drywalled, with an insulated door and 1/2" isocyanurate foam on the outside of a 2x4 framing. Single 16' garage door, insulated metal.
Should I place insulation batts directly above the garage ceiling drywall, or against the underside of the roof?

I don't need heavy insulation: I'm not trying to stem heat loss from the house itself, which is well insulated from the garage - just minimize the need for additional heating in the garage.

Thanks -

Shauns

Yes, I would just lay insulation batts between the trusses on top of your drywall. I did notice you did not say anything about insulation batts in your walls behind your sheetrock. The foan sheets you mentioned have very little R value.

The walls are not insulated. The wall structure is clapboard over ply, so maybe r-5 in the walls at most. They will need to have some insulation blown in ($$$).

I plan on using plastic-wrapped blankets to avoid the itch, since this will be accessed more than infrequently. I will need to create a surface above the batts to avoid compression. 2 x 6s spaced 6"-12" apart? or rip a panel of 1/2" plywood into 12" strips and space them 12" apart?

Any thoughts?

Thanks,

Shauns

Sounds to me your on the right track.