Fire investigators determined that the fire began on the second floor in a covered
walkway between the northeast wing and the center core, just outside of apartment 2J. The cause was identified as an exterior light fixture that
had been inverted from its usual operating position by one of the occupants and then
wrapped with a flannel shirt to reduce the light intensity into their bedroom. The fixture’s
incandescent bulb was enclosed by a clear plastic globe. By inverting the fixture,
the vent holes, which were intended to remove heat from the 60 watt bulb, were out of
position and the plastic globe in combination with the flannel shirt held in the heat. This
eventually resulted in the ignition of the shirt and the light fixture’s plastic globe. The
fire spread to the vinyl plastic siding and to the wooden stairway.
The siding fire quickly moved up the nearby open, wooden stairway before the
sidewall sprinkler on the wall opposite the light fixture was able to operate. The fire continued to burn upward until it reached the
ceiling of the fourth floor open walkway. At this point it entered the combustible attic
through a vent opening at the outside perimeter of the ceiling. The soffit vents in the
fourth floor core area were located inside, rather than outside, the perimeter support
beam for the roof. This design contained the heat and flames at the fourth floor ceiling
and allowed them to pass through the vent into the unprotected combustible attic. Once
in the attic, the fire was out of reach of the exterior sprinkler heads.
As the fire burned in the unsprinklered attic, it was able to quickly travel horizontally
to the fire/draft stops and then vertically up through the roof deck and down
into the apartments.
The fire consumed the structural supports for the roof, ceiling, and automatic
sprinkler system. As these items failed, the fire moved past the fire/draft stops into the
next attic section. The fire travel paths included burning across the combustible roof as
fire/draft stops do not penetrate the roof deck. In addition, the fire may have also burned
around the bottom of the draft stops as some of these stops may not have been placed in
line with the separation walls between apartments.
The fire also spread horizontally through the unprotected open wooden walkways
around the building’s core. This allowed the fire to spread to all four wings and all four floors through
the core’s open stairways. The fire also began dropping down from the attic to involve
the unprotected combustible balconies, which allowed the fire to spread into multiple
apartments through the large glass doors which opened onto the balconies. By the time
this fire encountered automatic sprinklers inside the apartment living areas, it had considerable
momentum and was already attacking the sprinkler supporting elements.
Next » Fire Department Rescue and Suppression Activities
Save to del.icio.us
