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The best way to protect your a structure from being damaged by a
wildland fire is to prevent it from starting on fire in the first place.
To do this, one must know of the many ways fire spreads from one fuel
source to another. Fire Spreads Through Radiation
One way a structure starts on fire is through radiation. Radiation
is caused from the heat from the flame itself. The amount of heat
produced depends on:
- The size of the flame. Generally, larger flames release more heat.
- The amount of surface area on the structure exposed to the radiant
heat. The larger the piece of surface that is exposed, the greater the
chance of ignition.
- Duration of exposure. The more time the structure is exposed the
greater the likelihood of ignition.
- The distance between the flames and the structure. The closer the
flames are to the structure, the greater the chance of ignition.
Fire Spreads Through Conduction
A second way a structure may start on fire is through conduction.
Conduction is caused by direct contact between the flame and the
structure. Firebrands, which are small pieces of burning material often
carried by wind, can start new fires, and are a common form of
conduction. Minimizing the chance of loss due to firebrand-started
ignitions include:
Fire Spreads Through Convection
Convection is a third way fire spreads. Convection is caused by
the superheated air that rises from the fires and pre-heats the fuels
above it. Convection is most often associated with steep slopes and the
"Chimney Effect". The best way to minimize loss due to convective
heating include:
- Build all structures back away from steep slopes. The edge of
these steep slopes often provides the best view but can also make the
home extremely difficult to protect during a wildland fire.
- Avoid building your home at the top of steep canyons.
If a structure is properly insulated from all these types of spreading,
the chances of the structure being lost or damaged to a wildfire will be
minimized.
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