An insulating material is described and comprised of loose fill short cellulose fibers and bonding synthetic fibers. The synthetic fibers are of longer length than the short cellulosic fibers and have an outer sheath which is heat-fused with outer sheaths of other synthetic fibers at crossing contact points thereof to form a matrix having pockets for retaining the loose fill cellulosic fibers therein and throughout the matrix thereby eliminating the need of an adhesive binder to retain the cellulose fibers in the matrix. The matrix can form a body having the shape of a batt of insulation and the batt may be provided with a facing sheet of suitable vapor permeability.