Firefighter Safety Report: Truss System Failures
NIOSH | John Howard M.D.
On September 5, 1998, a 54-year-old male career fire fighter (the victim) died when an exterior brick parapet wall collapsed on him. The warehouse was constructed of brick masonry walls with heavy timber trusses supporting the roof. The front and rear masonry walls extended above the peak of the roof, forming parapet walls.
The first responding officer ordered an exterior-only attack using deck guns and hose lines. The incident commander called dispatch to request mutual aid from three additional fire departments. A career department (including the victim) arrived on the scene approximately 15 minutes later and was positioned at the north end of the building and prepared for an exterior attack.
The victim approached the building to open a set of large doors (each 15 feet high by 6 feet wide) so that hose lines could be directed through the doors. The doors closed as the victim returned to the hose lines. The victim was approaching the building a second time to prop the doors open when the brick parapet wall suddenly collapsed outward, killing him instantly.
Fire fighters at the east side of the warehouse reported a partial roof collapse at approximately the same time the parapet wall on the north side collapsed [NIOSH 1998b].
On December 28, 2000, four career fire fighters were injured when a section of a church roof collapsed, trapping them inside. The roof system was formed using lightweight wooden trusses with gusset plate connectors. Two different truss systems were used in the different construction phases. The exterior peaked roof was covered with standard asphalt shingles.
The interior ceiling consisted of ½-inch drywall attached to the bottom of the trusses. Three 1¾-inch hose lines were advanced into the building by three crews. The incident commander ordered the first crew to enter the structure for an aggressive fire attack, cautioning them not to enter the structure very far. Two subsequent crews were sent into the building through a different set of doors.
Approximately 7 minutes after the first crew entered, the second and third crews met in a classroom. They noticed intense fire in the ceiling/truss void area where a small piece of ceiling in the classroom had fallen. Soon afterward, the roof collapsed in the classroom area, trapping and injuring four fire fighters. Three were able to escape by breaking through an exterior window.
The fourth fire fighter located the classroom door, and the incident commander led him into the hallway and out of the structure. The lightweight truss roof collapsed less than 10 minutes after the fire fighters entered the building [NIOSH 2001].