A FALL OF SUPPORTED ROOF OCCURRED ON A PANEL, 1 NORTH MAINS, 001 SECTION AT BREAK 27 IN THE INTERSECTION OF #3 ENTRY. NO INJURIES RESULTED, VENTILATION WAS NOT DISRUPTED, NO EQUIPMENT WAS INVOLVED. THE FALL MEASURED 20'DEEP X 45'WIDE X 5 1/2'HIGH. THE AREA WAS CRIBBED UP PRIOR TO THE FALL.