The I-joists in the lead photo here run across the top of the wall between the dining room and the attached garage in this home under construction in the Atlanta area. In the old days, before anyone worried about air moving through those joist cavities, the builder didn’t bother to do anything beyond securing the joists.
You can see here, though, that the builder of this home knows a thing or two about air sealing because they've put blocking between the joists. But what do they do next?
from Building Science http://www.greenbuildingadvisor.com/articles/dept/building-science/air-sealing-ceiling-joists-attached-garage