The wording in the IRC is vague on the requirements for 'attic' insulation in that it specifies 'ceiling' R-value requirements with the implication that it is referring to 'ceiling/attic' insulation, when it is in reality referring to insulation separating the 'attic' from the thermal envelope of the structure.
If we keep in mind that the intent is to insulate (and thus separate) the 'attic' from thermal envelope of the structure, then it also can be presumed that the intent is that this insulation is applicable to all surfaces which adjoin the attic, i.e, attic access hatches, attic access door, attic-ceiling surfaces, and attic-wall surfaces.
If the surface adjoins the attic then the required attic insulation R-value applies to that surface.
Thus, in your example, there is a door in a wall which opens to the attic, and (presumably) the attic floor is the ceiling to a portion of the thermal envelope of the house, thus the attic floor (ceiling to the space below) will require R-30 insulation, likewise the wall (and its opening - the door) to that attic also requires the same R-30 insulation.
Treating the door insulation R-value as being the same as the wall insulation R-value is the same as requiring the an attic access opening cover to have the same insulation R-value as required for the rest of the ceiling with the attic space above it - and that is presumed and done all the time.
Jerry Peck - CodeMan
Construction and Litigation Consultant
Construction Litigation Consultants, LLC.