A hair off topic here but I called the state yesterday to find out whats what with the rehab in NJ as I had a similar question.
Maybe it was posted before but:
If you do any work... new circuit, remodel or w/e in the existing footprint of the house you are under the 2005 code. You dont need any AFCI's anywhere (optional). Even a full gut of the existing house.
If its an addition aka new extension to the home you need to abide by the 2008 for AFCI's . AFCI= New construction only, my impression is smokes are included.
So Suzanne told us.