If it is to be considered a living space then it is a living room, sun room or similar room as noted in 210.12(B). Not only is AFCI required but the 6-12 receptacle spacing rule of 210.52 (A) applies.
If it is not to be considered a living space then it is a porch, deck, etc. as mentioned in 210.52(E)(3). Minimum of one receptacle is required and GFCI protection is required.
Your AHJ may determine if it is a living space or a porch, NEC does not really tell us which it is.
Kwired,
Seeing that you are from Nebraska and three-season rooms are probably typical, how does your AHJ determine a living space or a porch? Again, if it was an existing slab on the rear of the main structure and the contractor added three pre-fabbed walls and a pre-fabbed roof to the existing exterior wall and maintained the existing exterior envelope, would this be living space??
:?
I really don't know how AHJ would treat this space. At very least I would gues they would want 6-12 spacing rules to be met or it will be GFCI protected receptacles. Of course now with AFCI requirements that will also need to happen if the 6-12 rules apply. Really this response is based on how things would have been a few years ago before they brought in AFCI's (Nebraska amended AFCI's out of the code until late in the time period that they were still enforcing 2005 NEC which was sometime mid to late 2009)
I have only worked on one "three seasons room" that I can recall. It did not require permit or inspection. Most residential work does not unless installing a new service here.