Abstract: A device and method for simultaneously cutting and scoring pieces of insulation consisting of thick fiber on a foil backing, for joining pieces of insulation. A dolly is provided for carrying a fifty-pound roll of insulation so that insulation can be pulled from the roll and over an attached cutting surface. Two parallel rotary knives move together across the insulation on the cutting surface. One knife cuts through both the fiber and foil. The other knife simultaneously makes a parallel cut 1.5 inches from the first, through the fiber but not the foil, so that the fiber between the two cuts can be removed from the foil. The foil from which the fiber has been removed, can then be overlapped onto the foil of another piece of insulation to join the two pieces.