Ever wonder why firefighters climb
onto the roof of a building while it is on fire?
They are normally up there to open
up holes in the roof or upper-level windows, which could mean the difference
between life and death for people trapped inside a structure.
“Ventilation
is really critical,” said Raytown Battalion Chief Ben Denney, “To relieve the
heat and smoke and gases from a building is important for occupants and
firefighters.”
In order to
prepare to ventilate under the most trying conditions, firefighters train
in a variety of techniques, including tactics for opening the vents and crucial
communication between incident commanders and firefighters on the roof and
inside the building.
If an
occupant is trapped inside a building, in some cases, firefighters may not wait
until a vent has been opened before entering. But there is inherent danger in
entering such a structure or room within it, because there is a possibility of
explosive, deadly consequences, resulting from a backdraft or flashover.
In a
backdraft, the introduction of oxygen to a closed room or building causes an
explosion, when the oxygen ignites fuel gases, which were produced by the fire.
“The fire
is starving for air, so when it gets the air, it suddenly accelerates the
fire,” Denney explained.
The Raytown
Fire Protection District is continually seeking a variety of locations and
types of structures to prepare for all scenarios. A two-story building that
formerly housed the Toys r Us on Hillcrest road presented firefighters with the
opportunity to work on a spacious flat roof.
One of the
challenges of venting a building is to cut a hole in the decking — normally
about a 4-foot square — while avoiding damage to the rafters. If the rafters,
which support the roof’s exterior, are inadvertently slashed, that could cause
a disastrous roof collapse.
Firefighters
will tap on the roof with axe heads or other tools to try to sound out where
the rafters are, but that does not always yield information, especially if
there are multiple layers of shingles or the fire scene is extremely noisy.
“There are
several potential hazards associated with ventilation”, Interim Fire Chief Matt
Mace stated “At the same time firefighters are on the roof, the roof supports
could be rapidly deteriorating as a result of the fire.”
“You have to always be aware of the
possibility of a roof collapsing,” Mace said.
Firefighters
often try to vent at the highest possible point of a roof, because that is the
best place to remove the smoke and heat from the structure. A high point on the
roof often yields the advantage of providing a place to sit or stand more
safely than on a slope. But being at a higher elevation increases the risk of
injury in a fall.
Also, when
the vent hole is opened, the smoke and fire rush toward the hole, which could
possibly trap a firefighter.
A key to
success in fighting a fire is coordinating the attack between the firefighters
on the roof and those inside the building. The incident commander, normally a
battalion chief, can relay information by radio such as what part of the
building inside is ablaze, so the firefighters on the roof can know the best
spot to vent.
“One of the
first things to decide on a fire scene is where to vent,” said Ty Helphrey,
captain of Raytown Engine 51. “The sooner we get it open, the better it is for
us.”
