Abstract: AN EMPLOYEE FELL 20FT. (APPROX.) FROM A 2IN.X10IN PLANK TO THE CONCRETE FLOOR BELOW. HE WAS WALKING ON THE PLANK WHICH WAS LAID ACROSS THE HALLWAY WALLS. THE EMPLOYEE WAS ENGAGED IN PLACING JOIST ON THE SOUTHWEST SIDE OF THE APT. BLDG. ON WHAT WOULD BECOME THE SECOND FLOOR OF THE BUILDING. THE HALL WALL AND PERIMETER WALLS HAD BEEN EERECTED AND THE CREW WAS PLACING THE FLOOR JOIST FROM THE NORTH TO THE SOUTH AS THE ACCESS TO THE SOUTH WAS INACESSABLE TO THE FORK LIFT. MR. MOSS HAD JUST CARRIED A JOIST TO THE SOUTH SIDE AND WAS RETURNING TO THE NORTH SIDE TO GET ANOTHER JOIST. THE 2X10" PLANK LAYED ACROSS THE HALLWAY WALLS WAS COVERED WITH DEW OR HOAR FORST AND WAS DISPLACED BY THE EMPLOYEE'S FOOT AS HE STARTED ACROSS THE OPEN SPACE. THE EMPLOYEE STRUCK HIS HEAD ON THE WALL AND FELL TO THE CONCRETE FLOOR 8'BELOW.