At least one longitudinally extending series of cuts and separable connectors is formed in a fibrous insulation blanket with one or more rotating compression-cutting blades and a cooperating anvil to form separable blanket sections in the insulation blanket. The size and configuration of the teeth and notches in the compression-cutting blade, which may be determined through the use of an empirical equation, insure that the insulation blanket has the integrity to be handled and installed as a unit, but can be separated by hand into the blanket sections. The anvil has a moving surface that drives the compression-cutting blade at the velocity blanket is being fed between the cutting blade and the anvil.