Definitions for "Batts"
Pre-cut pieces of insulation in standard sizes; batts may have a facing of kraft paper, aluminum foil or poly (plastic) or no facing at all.
Pre-cut pieces of fiber glass insulation; batts may have a facing of paper or aluminum foil.
Precut lengths (four or eight feet) of insulation consisting of a filler of mineral wool or fiberglass and facings, one of which is a vapor barrier and flanges for nailing to the framing members such as studs or ceiling beams.