I am  building  an near passive house with an unvented crawl space . The perimeter is insulated with foam on part of the perimeter and  comfort board on the rest. New rat slab is put in .  Climate zone is 3a maritime north of San Francisco. Plans call for insulation between the joists. Should I insulate between the joists. Code says I have to insulate . If I do insulate should I also cover the bottom of the joists with comfort board? should I put in an air barrier  below the subfloor or below the bottom of the joist?