Chapter 8 Timber Truss Roof Collapse Flashcards
What did the tragic timber truss trilogy illustrate about fires in buildings with timber truss construction
truss collapse can push out masonry wall on FFers
ffers can fall through the collapsed truss roof
ffers can be crushed by collapsing truss roof
what is a timber
wooden construction larger than 2 x 4 but not large enough to be classified heavy timber
what is the most common design of a timber truss?
bowstring truss
what is the most dangerous roof system a firefighter will encounter
truss construction.. known to collapse during early stages of fire and will often cause subsequent collapse of front or rear masonry wall
a building with bowstring truss construction has how many bearing walls
4
a firefighter who discovers any type of truss in the building should immediately do what
informed command
in a timber trust building where will the main fire be located?
in the roof structure, not the content below
what are the three size up indicators of the trusts roof in the building?
- open space without columns
- mounted roof shape
- certain occupancies frequently use truss construction, such as supermarkets, bowling alleys, garages, theaters, places of worship, dealerships, piers and armories
when a fire extends to a timber truss attic space how should firefighters prepare?
prepare for defensive outside attack and protect exposures
what is the fire strategy of the first arriving engine company at a timber truss roofed building without a ceiling
attack the fire directly with a large diameter hose line with plenty of reach (50 feet). fire should show immediate signs of extinguishment or outside attack should be ordered
when attacking a fire in a timber Truss building when should a backup line be added
if the first hose line controls the fire, large backup line should be stretched to sweep the underside of the roof
when roof stability is assured and venting is needed how should firefighters ventilate
firefighters can sometimes open the skylights or scuttle covers quickly and leave the roof immediately… and vent openings may be made in the front and rear sloping portions of the roof
what is the key to safety when operating a fire in a trust constructed building
communications… when the truss is identified, notify command
what are the most unstable structures in the community
places of worship
at a church fire once the fire is knocked down what should be done
the walls and attic should be checked for concealed fire spread
what is a strategy when attacking a church fire
- first in officer sizes up fire to see if it can be extinguished by hose line
- large attack hoseline and backup should be stretched
- check walls and attic after fire knocked down
- withdrawal, defensive operations if first two lines unsuccessful
when should defensive operation set up begin at a church fire
while offensive attack is being initiated, if it fails defensive lines are ready
for defensive operations at a church, where should the first aerial be position to operate?
in a corner safe area (A/B or A/D)with the aerial raise to the rose window
At a church fire, if ventilation is needed to stretch the attack hose line.. how should this be accomplished
venting the stained-glass windows nearest the fire on both sides of the building
when the steeple is located at the front of the structure, what should be your concern
the A exposure wall must be considered a collapse hazard danger
in a church what do the wall support?
the roof
because of the church steeple in the interconnected roof inside bearing walls which exposures of a church are the most dangerous during a fire?
A, B, D are the most dangerous
if fire extends to the attic of a place of worship, what are your concerns?
the fire cannot be extinguished with handheld hose lines, severely limited access to attic space means no possibility to vent…. defensive operations
