Creating an Effective
Defensible Space, Continued
Step
Five:
IS THERE AN AREA AT LEAST 30 FEET WIDE SURROUNDING YOUR HOUSE THAT IS
“LEAN, CLEAN, AND GREEN”?
The area immediately adjacent to your house is particularly important
in terms of an effective defensible space. It is also the area that is
usually landscaped. Within an area extending at least 30 feet from the
house, the vegetation should be kept....
-
Lean—small amounts
of flammable vegetation,
-
Clean—no accumulation
of dead vegetation or other flammable debris,
-
Green—plants
are healthy and green during the fire season.
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Does Defensible Space Require A Lot Of Bare Ground In My Landscape?
No. Unfortunately, many people have this misconception.
While bare ground is certainly effective in reducing the wildfire threat, it is unnecessary and unacceptable due to
appearance, soil erosion, and other reasons. Many homes have attractive, well vegetated landscapes that also serve
as effective defensible space.
How Do I Change The Vegetation On My Property To Reduce The Wildfire Threat?
The objective of defensible space is to reduce
the wildfire threat to a home by changing the characteristics of the adjacent
vegetation.
-
Increase the
moisture content of vegetation.
-
Decrease the amount of flammable vegetation.
-
Shorten plant height.
-
Alter the arrangement
of plants.
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This is accomplished through the "Three R's of
Defensible Space" described in the table below.
| THE THREE R's OF DEFENSIBLE SPACE |
| REMOVAL |
This technique involves the elimination of entire plants, particularly trees and shrubs,
from the site. Examples of removal would be the cutting down of a dead tree or the cutting out of a flammable shrub. |
| REDUCTION |
The removal of plant parts, such as branches or leaves, constitute reduction.
Examples of reduction are pruning dead wood from a shrub, removing low tree branches, and mowing dried grass. |
|
REPLACEMENT |
Replacement is the substitution of less flammable plants for more hazardous vegetation.
For example, removal of a dense stand of flammable shrubs and planting an irrigated,
well maintained flower bed would be a type of replacement. |
Step
Six:
IS THE VEGETATION WITHIN THE RECOMMENDED DEFENSIBLE SPACE AREA MAINTAINED
ON A REGULAR BASIS?
Keeping your defensible space effective is a continual process. At least
annually, review these defensible space steps and take action accordingly.
An effective defensible space can be quickly diminished through neglect.
FIRE BRANDS AND THE WOOD SHAKE ROOF HAZARD
Firebrands are burning embers produced by wildfire that are lifted high
into the air and carried beyond the fire front. Firebrands are one of
the major causes of homes burned due to wildfire. Typical firebrand materials
include pine cones, bark, and if houses are involved, wood shakes and
shingles. Depending on wind speed and size of materials, firebrands can
be carried more than one-half mile ahead of the fire front.
A shower of thousands of firebrands can be produced during a major wildfire
event. If these firebrands land in areas with easily ignited fuels, numerous
spot fires can start. Homes located blocks away from the main fire front
can be threatened.
A house can be threatened by a wildfire in three ways: direct exposure
from flames, radiated heat, and airborne firebrands. Of these, firebrands
account for the majority of homes burned by wildfire. The roof of the
house is the most vulnerable to firebrands. Because of its angle, the
roof can catch and trap firebrands. If the roof is constructed of combustible
materials such as untreated wood shakes and shingles, the house is in
jeopardy of igniting and burning.
Not only are combustible roofing materials a hazard to the structure
on which they are installed, but they also pose a threat to other houses
in the vicinity. Burning wood shakes can become firebrands, be lifted
from the burning roof, and carried blocks away, and land in receptive
fuel beds such as other combustible roofs.
Unfortunately for homeowners with existing combustible roofs, there
are no long-term reliable measures available to reduce roof vulnerability
to wildfire other than re-roofing with fire resistant materials.
Click
to Open a New Window Showing Illustrations of the Steps to Creating Defensible
Space
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