QUICK GUIDE SERIES		

FIRE 2012-1

Protecting Your Home from Wildfire:
Creating Wildfire-Defensible Zones
Formerly CSU Extension Factsheet 6.302

If your home is located in the natural vegetation of Colorado’s
grasslands, shrublands, foothills or mountains, you live in the
wildland-urban interface (WUI) and are inherently at risk froma wildfire. The WUI is any area where structures and other humandevelopments meet or intermingle with wildland vegetative fuels.
In many vegetation types, it is not a matter of if a wildfire will
impact your home, but when.
Wildfires are a natural part of Colorado’s varied forest ecosystems.
Many rural communities are located in areas historically prone tofrequent natural wildfires. Living in the wildland requires more
self-reliance than living in urban areas. It may take longer for a fireengine to reach your area, and a small fire department can easily
become overwhelmed during an escalating wildfire. Planning ahead and taking
actions to reduce fire hazards can increase your safety and help protect yourproperty. As more people choose to live in areas prone to wildfire, additional
homes and lives are potentially threatened every year. Firefighters always do theirbest to protect rural residents, but ultimately, it is YOUR responsibility to protect
your life, family, animals and property from wildfire.
The information contained in this document is for use by individual landowners
to help reduce wildfire risk on their property. In order to effectively protect
subdivisions and communities, alllandowners must work together
to reduce fire hazards within
and adjacent to communities.
This includes treating individual
home sites and common areas
within communities, and creating
fuelbreaks within and adjoining
the community where feasible. This
document will focus on actionsindividual landowners can take toreduce wildfire hazards on their
Figure 2: Colorado’s grasslands, shrublands, foothills property. For additional informationand mountains all have areas in the wildland-urban
on broader community protection,interface where human development meets wildland
go to www.csfs.colostate.edu.
vegetative fuels. Photo: CSFS
In this guide, you’ll read about steps you can take to protect your property fromwildfire. These steps focus on beginning work closest to your house and moving
outward. Also, remember that keeping your home safe is not a one-time effort – itrequires ongoing maintenance. It may be necessary to perform some actions, suchas removing pine needles from gutters and mowing grasses and weeds several
times a year, while other actions may only need to be addressed once a year. While

Figure 1: Firefighters will dotheir best to protect homes, butultimately it is the homeowner’s
responsibility to plan ahead andtake actions to reduce fire hazards
around structures. Photo: National
Interagency Fire Center

This quick guide was produced by
the Colorado State Forest Service
to promote knowledge transfer.
October 2012www.csfs.colostate.edu
1you may not be able to accomplish ALL of the actions described in this document
to prepare your home for wildfire, each completed activity will increase the safetyof your home, and possibly your family, during a wildfire.
(Note: These guidelines are adapted for ponderosa pine, Douglasfir and mixed-conifer ecosystems below 9,500 feet. See page 9 for
guidelines adapted to other forest ecosystems.)

This guide primarily will help design your defensible space.
Defensible space is the natural and landscaped area around ahome or other structure that has been modified to reduce fire
hazard. Defensible space gives your home a fighting chanceagainst an approaching wildfire. Creating defensible space
also reduces the chance of a structure fire spreading to thesurrounding forest and other homes.

Figure 3: Burning embers can be carried
long distances by wind. Embers ignite
structures when they land in gaps,
crevices and other combustible places
around the home. Photo: CSFS

Remember...
• Reducing fuels arounda home will increase
the chances forsurvival in a wildfire,
but there is no
guarantee.
• This quick guideprovides minimum
guidelines. The more
fuels you remove, thegreater the chanceyour home will survive.
• Working withyour neighbors
and community
will increase theeffectiveness of yourhome’s defensible
space.

Three factors determine wildfire behavior: fuels, weather andtopography. We cannot alter weather or topography, so wemust concentrate on altering fuels. Fuels include vegetation,such as trees, brush and grass; near homes, fuels also include
such things as propane tanks, wood piles, sheds and even homes themselves.
Some plant species are more flammable than others, and the flammability ofvegetative fuels changes depending on the season, recent weather events, andother factors such as drought. Fuel continuity and density also play an importantrole in wildfire.
Wildfire often creates its own weather conditions. Hot rising air and associatedwinds can carry embers and other burning materials into the atmosphere for long
distances, where they can ignite vegetation and structures up to several miles
away. Embers have caused the loss of many homes during wildfires.
As you think about protecting your home and property from wildfire, consider
how you can manage fuels on your property to prevent fire from spreading to
your home and other structures.
For more information on wildfire behavior, please see FireWise Construction: Site
Design and Building Materials at www.csfs.colostate.edu.

Fuel Arrangement and Types
When fuels are abundant, a fire can be uncontrollable and destructive. But whenfuels are scarce, a fire cannot build momentum and intensity, which makes itmuch easier to control and is more likely to be beneficial to the land.
The more dense and continuous the fuels, the bigger the threat they pose to yourhome. The measure of fuel hazard refers to its continuity, both horizontal andvertical. Horizontal continuity refers to fuels across the ground, while verticalcontinuity refers to fuels extending from the ground up into the crowns of trees
and shrubs. Fuels with a high degree of both vertical and horizontal continuity
are the most hazardous, particularly when they occur on slopes. Mitigation of
wildfire hazards focuses on breaking up the continuity of horizontal and verticalfuels.
Heavier fuels, such as brush and trees, produce a more intense fire than light fuels,
such as grass. However, grass-fueled fires travel much faster than heavy-fueledfires. Some heavier surface fuels, such as logs and wood chips, are potentiallyhazardous heavy fuels and also should be addressed.

2Vertical/Ladder Fuels
Ladder fuels are defined as smaller trees and brush that provide vertical continuity, whichallows a fire to burn from the ground level up into the branches and crowns of larger trees.
Lower branches on large trees also can act as ladder fuels. These fuels are potentially very
hazardous, but are easy to mitigate. The hazards from ladder fuels near homes are especially
important to address. Prune all tree branches from ground level up to a height of 10 feetabove ground or up to 1/3 the height of the tree, whichever is less. Do not prune further
up because it could jeopardize the health of the tree. Shrubs should be pruned based on
specifications recommended for the species. Dead branches should be removed wheneverpossible.

Surface Fuels
Logs/Branches/Slash/Wood Chips
Naturally occurring woody material on the ground and debris from cutting down trees(also known as slash) may increase the intensity of fires. Increased fire intensity makes afire harder to control and increases the likelihood of surface fires transitioning to crown
fires. Dispose of any heavy accumulation of logs, branches and slash by chipping, haulingto a disposal site or piling for burning later. Always contact your county sheriff ’s office or
local fire department first for information about burning slash piles. Another alternative is
to lop and scatter slash by cutting it into very small pieces and distributing it widely overthe ground. If chipping logs and/or slash, it’s essential to avoid creating continuous areasof wood chips on the ground. Break up the layer of wood chips by adding nonflammablematerial, or allow for wide gaps (at least 3 feet) between chip accumulations. Also, avoid
heavy accumulation of slash by spreading it closer to the ground to speed decomposition. If
desired, two or three small, widely spaced brush piles may be left for wildlife habitat. Locate
these well away from your home (NOT in Zones 1 or 2; see page 5-8 for zone descriptions).

Figure 4: Ladder fuels are shrubs
and low branches that allow a
wildfire to climb from the groundinto the tree canopy. Photo: CSFS

Figure 5: Surface fuels include logs,
branches, wood chips, pine needles,
duff and grasses. Photo: CSFS

Pine Needles/Duff Layers
Due to decades of fire suppression, decomposing layers of pine needles, twigs and other organic debris–called duff – isdeeper under many large trees today than it would have been a century ago. This is especially true in ponderosa pine forests
where frequent and naturally occurring fires have been absent. These large trees often are lost when fires occur, because
flames burning in the duff layer can pre-heat live vegetation and ignite the trees, or the tree’s roots can be damaged from theintense heat of the smoldering duff, killing the tree. It is important to rake needle or duff
layers deeper than 2 inches at least 3 feet away from the base of large trees. This should bedone annually, and the additional duff also should be removed from the area.
Grasses
Grasses are perhaps the most pervasive and abundant surface fuel in Colorado. Mow grasses
and weeds as often as needed throughout the growing season to keep them shorter than 6
inches. This applies to irrigated lawns and wild or native grasses. This is critical in the fall,when grasses dry out, and in the spring, after the snow is gone but before plants green-up.
Be especially careful when mowing in areas with rocks. Mower blades can hit rocks andcreate sparks, causing fires in dry grass. Consider mowing only on days with high humidity
or after recent moisture to reduce the risk of starting an unwanted fire.

Figure 6: Tree canopies offer fuelfor intense crown fires. Photo: Paul
Mintier

When mowing around trees, be sure to avoid damaging the root system and tree trunk byusing a higher blade setting on the mower and trimming grass that grows against the trunk only by hand.

Crown Fuels
An intense fire burning in surface fuels can transition into the upper portion of the tree canopies and become a crown
fire. Crown fires are dangerous because they are very intense and can burn large areas. Crown fire hazard can be reducedby thinning trees to decrease crown fuels, reducing surface fuels under the remaining trees, and eliminating vertical fuelcontinuity from the surface into the crowns. Specific recommendations are provided in the Defensible Space Management
Zones, pages 5-8.

3

The Home Ignition Zone
Structure Ignitability

Defensible Space

The Home Ignition Zone
Figure 7: Addressing both componentsof the Home Ignition Zone will provide
the best protection for your home.
Credit: CSFS

Figure 8: (above)
Wood shingle
roofs are highly
flammable andnot recommended.
Photo: CSFS
Figure 9: (above right) Class A roofing
materials including tile, clay, concrete,
slate and asphalt shingles are fireresistant options. Photo: CSFS

Two factors have emerged as the primary determinants of a home’s
ability to survive a wildfire – the quality of the defensible space anda structure’s ignitability. Together, these two factors create a concept
called the Home Ignition Zone (HIZ), which includes the structure
and the space immediately surrounding the structure. To protect ahome from wildfire, the primary goal is to reduce or eliminate fuels andignition sources within the HIZ.

Structural Ignitability

The ideal time to address home ignition risk is when the structure isin the design phase. However, you can still take steps to reduce ignitability to an
existing home.
The roof has a significant impact on a structure’s ignitability because of its
extensive surface area. When your roof needs significant repairs or replacement,
use only fire-resistant roofing materials. Also, check with your county building
department – some counties now have restrictions against using wood shingles
for roof replacement or require specific classifications of roofing material. Woodand shake-shingle roofs are discouraged because they are highly flammable,
and are prohibited in some areas of the state. Asphalt shingles, metal sheets andshingles, tile, clay tile, concrete and slate shingles are all recommended
roofing materials.
The extension of the roof beyond the exterior structure wall is theeave. This architectural feature is particularly prone to ignition. As fire
approaches the building, the exterior wall deflects hot air and gasses
up into the eave. If the exterior wall isn’t ignition-resistant, this effect is
amplified.
Most decks are highly combustible. Their shape traps hot gasses,
making them the ultimate heat traps. Conventional wooden decks are so
combustible that when a wildfire approaches, the deck often ignites before the fire
reaches the house.
The exterior walls of a home or other structure are affected most by radiant heatfrom the fire and, if defensible space is not adequate, by direct contact with flames
from the fire.
Windows are one of the weakest parts of a building with regard to wildfire.
They usually fail before the building ignites, providing a direct path forflames and airborne embers to reach the building’s interior.
Burning embers are produced when trees and structures are consumed by
wildfire. These embers sometimes can travel more than a mile. Flammablehorizontal or nearly horizontal surfaces, such as wooden decks or shakeshingle roofs, are especially at risk for ignition from burning embers. Since
airborne embers have caused the loss of many homes in the WUI, addressing
structural ignitability is critical, even if the area surrounding a home is notconducive to fire spread.

Figure 10: Decks, exterior walls andwindows are important areas to
examine when addressing structure
ignitability. Photo: CSFS

This guide provides only basic information about structural ignitability. For
more information on fire-resistant building designs and materials, refer to the
CSFS FireWise Construction: Site Design and Building Materials publication atwww.csfs.colostate.edu.

4Defensible Space
Defensible space is the area around a home or other structurethat has been modified to reduce fire hazard. In this area,
natural and manmade fuels are treated, cleared or reduced
to slow the spread of wildfire. Creating defensible space also
works in the reverse, and reduces the chance of a structure fire
spreading to neighboring homes or the surrounding forest.
Defensible space gives your home a fighting chance against an
approaching wildfire.
Creating an effective defensible space involves a series ofmanagement zones in which different treatment techniques
are used. Develop these zones around each building on yourproperty, including detached garages, storage buildings, barns
and other structures.

Figure 11: Homesite before defensible
space. Photo: CSFS

The actual design and development of your defensible space depends on several
factors: size and shape of building(s), construction materials, slope of the ground,surrounding topography, and sizes and types of vegetation on
your property. You may want to request additional guidancefrom your local Colorado State Forest Service forester, fire
department or a consulting forester as you plan a defensible
space for your property.
Defensible space provides another important advantage during afire: increased firefighter safety. Firefighters are trained to protect
structures only when the situation is relatively safe for them todo so. They use a process called “structural triage” to determine
if it is safe to defend a home from an approaching wildfire. The
presence or absence of defensible space around a structure isa significant determining factor used in the structural triage
process, as defensible space gives firefighters an opportunity to
do their job more safely. In turn, this increases their ability to protect your home.

Figure 12: Homesite after creating adefensible space. Photo: CSFS

If firefighters are unable to directly protect your home during a wildfire, having
an effective defensible space will still increase your home’s chance of survival. It
is important to remember that with wildfire, there are no guarantees. Creatinga proper defensible space does not mean that yourhome is guaranteed to survive a wildfire, but it doessignificantly improve the odds.
Zone 1

Defensible SpaceManagement Zones

0-15/30
feet

Zone 2

Zone 330-100
feet

100+
feet

Three zones need to be addressed when creating
defensible space:
Zone 1 is the area nearest the home and otherstructures. This zone requires maximum hazard
reduction.
Zone 2 is a transitional area of fuels reduction
between Zones 1 and 3.
Zone 3 is the area farthest from the home. It extends
from the edge of Zone 2 to your property boundaries.

Defensible Space Zones
Figure 13: Defensible space managementzones. Credit: CSFS

5

Zone 1
The width of Zone 1 extends a minimum distance of 15-30 feet outward from astructure, depending on property size. Most flammable vegetation is removed inthis zone, with the possible exception of a few low-growing shrubs or fire-resistant
plants. Avoid landscaping with common ground junipers, which are highly
flammable.

Figure 14: This homeowner worked
hard to create a defensible space aroundthe home. Notice that all fuel has
been removed within the first 5 feet ofthe home, which survived the Waldo
Canyon Fire in the summer of 2012.
Photo: Christina Randall, Colorado
Springs Fire Department

Figure 15: Clearing pine needles andother debris from the roof and gutters is
an easy task that should be done at least
once a year. Photo: CSFS

Increasing the width of Zone 1 will increase the structure’s survivability. Thisdistance should be increased 5 feet or more in areas downhill from a structure.
The distance should be measured from the outside edge of the home’s eaves
and any attached structures, such as decks. Several specific treatments arerecommended within this zone:•

Install nonflammable ground cover and plant nothing within the first 5 feetof the house and deck. This critical step will help prevent flames from coming
into direct contact with the structure. This is particularly important if abuilding is sided with wood, logs or other flammable materials. Decorativerock creates an attractive, easily maintained, nonflammable ground cover.

•If a structure has noncombustible siding (i.e., stucco, synthetic stucco,concrete, stone or brick), widely spaced foundation plantings of low-growing
shrubs or other fire-resistant plant materials are acceptable. However, do notplant directly under windows or next to foundation vents, and be sure areas ofcontinuous grass are not adjacent to plantings. Information on fire-resistant
plants is available on the CSFS website at www.csfs.colostate.edu.

•

Prune and maintain any plants in Zone 1 to prevent excessive growth. Also,
remove all dead branches, stems and leaves within and below the plant.

•

Irrigate grass and other vegetation during the growing season. Also, keep wild
grasses mowed to a height of 6 inches or less.

•

Do not store firewood or other combustible materials anywhere in this zone.
Keep firewood at least 30 feet away from structures, and uphill if possible.

•

Enclose or screen decks with 1/8-inch or smaller metal mesh screening(1/16-inch mesh is preferable). Do not use areas under decks for storage.

•

Ideally, remove all trees from Zone 1 to reduce fire hazards. The more trees
you remove, the safer your home will be.

•

If you do keep any trees in this zone, consider them part of the structure andextend the distance of the entire defensible space accordingly.

•

Remove any branches that overhang or touch the roof, and remove all fuels
within 10 feet of the chimney.

•

Remove all pine needles and other debris from the roof, deck and gutters.

•

Rake pine needles and other organic debris at least 10 feet away from all decks
and structures.

•

Remove slash, wood chips and other woody debris from Zone 1.

Zone 2
Figure 16: Enclosing decks with metal
screens can prevent embers from
igniting a house. Photo: Marilyn
Brown, La Plata County

Zone 2 is an area of fuels reduction designed to diminish the intensity of a fire
approaching your home. The width of Zone 2 depends on the slope of the groundwhere the structure is built. Typically, the defensible space in Zone 2 should
extend at least 100 feet from all structures. If this distance stretches beyond yourproperty lines, try to work with the adjoining property owners to complete an
appropriate defensible space.
6

The following actions help reduce continuous fuels surrounding a structure, while enhancing home safety and the aestheticsof the property. They also will provide a safer environment for firefighters to protect your home.
Tree Thinning and Pruning• Remove stressed, diseased, dead or dying trees and shrubs.
This reduces the amount of vegetation available to burn, andmakes the forest healthier.

10-foot
spacing
between tree
crowns

Tree
Crown

•

Remove enough trees and large shrubs to create at least 10
feet between crowns. Crown separation is measured from theoutermost branch of one tree to the nearest branch on thenext tree. On steep slopes, increase the distance between tree
crowns even more.

•

Remove all ladder fuels from under remaining trees. Prune tree
branches off the trunk to a height of 10 feet from the groundFigure 17: In Zone 2, make sure there is at least a 10-foot spacingor 1/3 the height of the tree, whichever is less.
between tree crowns. Credit: CSFS•

If your driveway extends more than 100 feet from your home, thin out trees within a 30 foot buffer along both sides ofyour driveway, all the way to the main access road. Again, thin all trees to create 10-foot spacing between tree crowns.

•

Small groups of two or three trees may be left in some areas of Zone 2, but leave a minimum of 30 feet between thecrowns of these clumps and surrounding trees.

•

Because Zone 2 forms an aesthetic buffer and provides a transition between zones, it is necessary to blend therequirements for Zones 1 and 3. For example, if you have a tree in Zone 2 with branches extending into Zone 1, the tree
can be retained if there is proper crown spacing.

•

Limit the number of dead trees (snags) to one or two per acre. Be sure snags cannot fall onto the house, power lines,
roads or driveways.

•

As in Zone 1, the more trees and shrubs removed, the more likely your house will survive a wildfire.

Shrub Thinning/Pruning and Surface Fuels• Isolated shrubs may be retained in Zone 2, provided they are
not growing under trees.
•

Keep shrubs at least 10 feet away from the edge of tree
branches. This will prevent the shrubs from becoming ladderfuels.

•

Minimum spacing recommendations between clumps ofshrubs is 2 1/2 times the mature height of the vegetation.
The maximum diameter of the clumps themselves shouldbe twice the mature height of the vegetation. As with treecrown spacing, all measurements are made from the edge ofvegetation crowns.

Zone 2 Tree Thinning

Pruning trees and shrubs will help preventa wildfire from traveling up ladder fuels10
feet

Ladder
Fuels

Zone 2 Tree and Shrub Pruning
Figure 18: Pruning trees will help prevent a wildfire from climbing
from the ground to the tree crowns. Credit: CSFS•

Example – For shrubs 6 feet high, spacing between shrub
clumps should be 15 feet or more (measured from the edgeof the crowns of vegetation clumps). The diameter of these shrub clumps should not exceed 12 feet.

•

Periodically prune and maintain shrubs to prevent excessive growth, and remove dead stems from shrubs annually.
Common ground junipers should be removed whenever possible because they are highly flammable 			and tend to hold a layer of duff beneath them.

•

Mow or trim wild grasses to a maximum height of 6 inches. This is especially critical in the fall, when grasses dry out.

•

Avoid accumulations of surface fuels, such as logs, branches, slash and wood chips greater than 4 inches deep.

7

Firewood• Stack firewood uphill from or on the same elevation as any structures,
and at least 30 feet away.
•

Clear all flammable vegetation within 10 feet of woodpiles.

•

Do not stack wood against your home or on/under your deck, evenin the winter. Many homes have burned as a result of a woodpile that
ignited first.

Propane Tanks and Natural Gas Meters• Locate propane tanks and natural gas meters at least 30 feet from any
structures, preferably on the same elevation as the house.

Figure 19: Keep firewood, propane tanks and natural gas•

meters at least 30 feet away from structures. Photo: CSFS
The tank should not be located below your house because if it ignites,
the fire would tend to burn uphill. Conversely, if the tank or meter is located above your house and it develops a leak, gas
will flow downhill into your home.

•

Clear all flammable vegetation within 10 feet of all tanks and meters.

•

Do not visibly screen propane tanks or natural gas meters with shrubs, vegetation or flammable fencing. Instead, install
5 feet of nonflammable ground cover around the tank or meter.

Zone 3
Zone 3 has no specified width. It should provide a gradual transition from Zone 2
to areas farther from the home that have other forest management objectives. Your
local Colorado State Forest Service forester can help you with this zone.
This zone provides an opportunity for you to improve the health of the forest
through proper management. With an assortment of stewardship options, you canproactively manage your forest to reduce wildfire intensity, protect water quality,
improve wildlife habitat, boost the health and growth rate of your trees, andincrease tree survivability during a wildfire.

Figure 20: This ponderosa pine forest has
been thinned, which will not only help reduce
the wildfire hazard, but also increase tree
health and vigor. Photo: CSFS

In addition, properly managed forests can provide income, help protect trees
against insects and diseases, and even increase the value of your property. Typicalforest management objectives for areas surrounding home sites or subdivisions
provide optimum recreational opportunities; enhance aesthetics; improve tree
health and vigor; provide barriers against wind, noise, dust and visual intrusions;
support production of firewood, fence posts and other forest commodities; orcultivate Christmas trees or trees for transplanting.
Consider the following when deciding forest management objectives in Zone 3:•

The healthiest forest is one that includes trees of multiple ages, sizes and species, and where adequate growing room ismaintained over time.

•

Remember to consider the hazards associated with ladder fuels. A forest with a higher canopy reduces the chance of asurface fire climbing into the tops of the trees, and might be a priority if this zone has steep slopes.

•

A greater number of snags – two or three per acre, standing or fallen – can be retained in Zone 3 to provide wildlife
habitat. These trees should have a minimum diameter of 8 inches. Make sure that snags pose no threat to power lines orfirefighter access roads.

•

While tree pruning generally is not necessary in Zone 3, it may be a good idea from the standpoint of personal safety toprune trees along trails and firefighter access roads. Or, if you prefer the aesthetics of a well-manicured forest, you mightprune the entire area. In any case, pruning helps reduce ladder fuels within tree stands, thus reducing the risk of crown
fire.

•

Mowing grasses is not necessary in Zone 3.

•

Any approved method of slash treatment is acceptable, including piling and burning, chipping or lop-and-scatter.

8

Other Recommendations
Windthrow
In Colorado, some tree species, including lodgepole pine, Engelmann
spruce and Douglas-fir, are especially susceptible to damage anduprooting by high winds or windthrow. If you see evidence of thisproblem in or near your home, consider making adjustments to thedefensible space guidelines. It is highly recommended that you contact
a professional forester to help design your defensible space, especially if
you have windthrow concerns.
Water Supply
If possible, make sure that an on-site water source is readily available
for firefighters to use, or that other water sources are close by. Lakes,
ponds, swimming pools and hot tubs are all possible options. If there are no
nearby water sources, consider installing a well-marked dry hydrant or cistern. If
your primary water source operates on electricity, be sure to plan for a secondarywater source. During wildfires, structures often are cut off from electricity. For
more information on how to improve the accessibility of your water
source, contact your local fire department.

Figure 21: During high winds, theselodgepole pine trees fell onto the house.
Lodgepole pine is highly susceptible towindthrow. Photo: CSFS

Recommendations for Specific Forest
Types
The above recommendations refer primarily to ponderosa pine,
Douglas-fir and mixed-conifer ecosystems. For other forest types,
please refer to the additional recommendations below:
Aspen
Tree spacing and ladder fuel guidelines do not apply to mature standsof aspen trees. Generally, no thinning is recommended in aspen
forests, regardless of tree size, because the thin bark is easily damaged,
making the tree easily susceptible to fungal infections. However, inolder stands, numerous dead trees may be on the ground and require removal.
Conifer trees often start growing in older aspen stands. A buildup of these trees
eventually will increase the fire hazard of the stand, so you should remove theyoung conifers. Brush also can increase the fire hazard and should be thinned toreduce flammability.

Figure 22: Mature aspen stands cancontain many young conifers, deadtrees and other organic debris. This canbecome a fire hazard. Photo: CSFS

Lodgepole Pine
Lodgepole pine management in the WUI is much different than thatfor lodgepole pine forests located away from homes, communities andother developments. Normally, it is best to develop fuels management
and wildfire mitigation strategies that are informed and guided by theecology of the tree species. This is not the case with lodgepole pine.
Older lodgepole pine stands generally do not respond well to selective
thinning, but instead respond better to the removal of all trees over adefined area to allow healthy forest regeneration. Selectively thinning
lodgepole can open the stand to severe windthrow and stem breakage.
However, if your home is located within a lodgepole pine forest, you
may prefer selective thinning to the removal of all standing trees.
To ensure a positive response to thinning throughout the life of a lodgepole pine
stand, trees must be thinned early in their lives – no later than 20 to 30 years after
germination. Thinning lodgepole pine forests to achieve low densities can best be

Figure 23: A young lodgepole pine stand.
Thinning lodgepole pines early on in theirlives will help reduce the wildfire hazard
in the future. Photo: CSFS

9

accomplished by beginning when trees are small saplings, and maintaining thosedensities through time as the trees mature.

The defensible space
guidelines in this quick
guide are predominantly
for ponderosa pine andmixed-conifer forests.
These guidelines will varywith other forest types.

Thinning older stands of lodgepole pine to the extent recommended for defensible
space may take several thinning operations spaced over a decade or more. Whenthinning mature stands of lodgepole pine, do not remove more than 30 percentof the trees in each thinning operation. Extensive thinning of dense, pole-sized
and larger lodgepole pine often results in windthrow of the remaining trees. Focus
on removing trees that are obviously lower in height or suppressed in the forest
canopy. Leaving the tallest trees will make the remaining trees less susceptible towindthrow.
Another option is leaving clumps of 30-50 trees. Clumps are less susceptible
to windthrow than solitary trees. Allow a minimum of 30-50 feet between tree
crowns on the clump perimeter and any adjacent trees or clumps of trees. Wildfire
tends to travel in the crowns of lodgepole pine. By separating clumps of trees withlarge spaces between crowns, the fire is less likely to sustain a crown fire.
Piñon-Juniper
Many piñon-juniper (PJ) forests are composed of continuous fuel that is
highly flammable. Fire in PJ forests tend to burn intensely in the crowns oftrees. Try to create a mosaic pattern when you thin these trees, with a mixtureof individual trees and clumps of three to five trees. The size of each clump
will depend on the size, health and location of the trees. The minimum
spacing between individual trees should be 10 feet between tree crowns, withincreasing space for larger trees, clumps, and stands on steeper slopes.

Figure 24: Piñon-juniper forests areoften composed of continuous fuels.
Creating clumps of trees with large
spaces in between clumps will break up
the continuity. Photo: CSFS

Tree pruning for defensible space is not as critical in PJ forests as in pine or fir
forests. Instead, it is more important to space the trees so that it is difficult for
the fire to move from one tree clump to the next. Trees should only be pruned
to remove dead branches or branches that are touching the ground. However,
if desired, live branches can be pruned to a height of 3 feet above the ground.
Removing shrubs that are growing beneath PJ canopies is recommended toreduce the overall fuel load that is available to a fire.
It is NOT recommended to prune live branches or remove PJ trees between
April and October, when the piñon ips beetle is active in western Colorado. Any
thinning activity that creates the flow of sap in the summer months can attract
these beetles to healthy trees on your property. However, it is acceptable to remove
dead trees and dead branches during the summer months.
For more information, please refer to the CSFS Piñon-Juniper Management
Quick Guide at www.csfs.colostate.edu.

Figure 25: Gambel oak needs to betreated in a defensible space at least
every 5-7 years because of its vigorous
growing habits. Photo: CSFS

Gambel Oak
Maintaining Gambel oak forests that remain resistant to the spread of wildfire
can be a challenge because of their vigorous growing habits. Gambel oak trees
grow in clumps or groves, and the stems in each clump originate from thesame root system. Most reproduction occurs through vegetative sprouts fromthis deep, extensive root system. You may need to treat Gambel oak near yourhome every five to seven years. Sprouts also should be mowed at least once
every year in Zones 1 and 2. Herbicides can be used to supplement mowing
efforts for controlling regrowth.
For more information, please refer to the CSFS Gambel Oak Management
publication at www.csfs.colostate.edu.
Note: This publication does not address high-elevation spruce-fir forests. For information on
this forest type, please contact your local CSFS district office.

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Maintaining Your Defensible SpaceYour home is located in a dynamic environment that is always changing. Trees, grasses and shrubs continue to grow, die orare damaged, and drop their leaves and needles each season. Just like your home, the defensible space around it requires
regular, ongoing maintenance to be effective. Use the following checklists to build and maintain your defensible space.

Defensible Space: Initial Projects☐☐ Properly thin and prune trees and shrubs within Zones 1 and 2.
☐☐ Dispose of slash from tree/shrub thinning.
☐☐ Screen attic, roof, eaves and foundation vents, and periodically check them to ensurethat they are in good condition.
☐☐ Screen or wall-in stilt foundations and decks; screens should be 1/8-inch or smaller
metal mesh (1/16-inch mesh is best).
☐☐ Post signs at the end of the driveway with your last name and house number that arenoncombustible, reflective and easily visible to emergency responders.

Figure 26: Keeping the forest properly
thinned and pruned in a defensible space will
reduce the chances of a home burning during
a wildfire. Photo: CSFS☐☐ Make sure that the driveway is wide enough for fire trucks to enter and exit, and thattrees and branches are adequately cleared for access by fire and emergency equipment. Contact your local fire department or check
the CSFS website for information specific to access.
☐☐ Take pictures of your completed defensible space for comparison of forest growth over time.

Defensible Space Tasks: Annual Requirements☐☐ Clear roof, deck and gutters of pine needles and other debris. *☐☐ Mow grass and weeds to a height of 6 inches or less. *☐☐ Rake all pine needles and other flammable debris away from the foundation of yourhome and deck. *☐☐ Remove trash and debris accumulations from the defensible space.*☐☐ Check fire extinguishers to ensure that they have not expired and are in good working
condition.
☐☐ Check chimney screens to make sure they are in place and in good condition.
☐☐ Remove branches that overhang the roof and chimney.

Figure 27: Sharing information and working
with your neighbors and community will give
your home and surrounding areas a betterchance of surviving a wildfire. Photo: CSFS☐☐ Check regrowth of trees and shrubs by reviewing photos of your original defensible space; properly thin and prune trees and shrubs
within Zones 1 and 2.
☐☐ Dispose of slash from tree/shrub thinning. **Address more than once per year, as needed.

Be Prepared☐☐ Complete a checklist of fire safety needs inside your home (these should be available at your local fire department). Examples include
having an evacuation plan and maintaining smoke detectors and fire extinguishers.
☐☐ Develop your fire evacuation plan and practice family fire drills. Ensure that all family members are aware of and understand escaperoutes, meeting points and other emergency details.
☐☐ Contact your county sheriff ’s office and ensure that your home telephone number and any other important phone numbers appear in
the county’s Reverse 911 or other emergency notification database.
☐☐ Prepare a “grab and go” disaster supply kit that will last at least three days, containing your family’s and pets’ necessary items, such as
cash, water, clothing, food, first aid and prescription medicines.
☐☐ Ensure that an outdoor water supply is available. If it is safe to do so, make a hose and nozzle available for responding firefighters. The
hose should be long enough to reach all parts of the house.
11Preparing your home and property from wildfire is a necessity if youlive in the wildland-urban interface. It is important to adequately
modify the fuels in your home ignition zone. Remember, every task
you complete around your home and property will make your homemore defensible during a wildfire.
Always remember that creating and maintaining an effective
defensible space in the home ignition zone is not a one-timeendeavor – it requires an ongoing, long-term commitment.
If you have questions, please contact your local CSFS district office.
Contact information can be found at www.csfs.colostate.edu.

List of Additional Resources•

The Colorado State Forest Service, http://www.csfs.colostate.edu•

CSFS wildfire-related publications,
http://csfs.colostate.edu/pages/wf-publications.html•

Community Wildfire Protection Planning,
http://csfs.colostate.edu/pages/community-wf-protection-planning.html•

Colorado’s “Are You FireWise?” information,
http://csfs.colostate.edu/pages/wf-protection.html•

National Fire Protection Association’s Firewise Communities USA,
http://www.firewise.org•

Fire Adapted Communities, http://fireadapted.org/•

Ready, Set, Go!, http://wildlandfirersg.org/

Figure 29: This house survived the Fourmile Canyon Fire in 2010.

Photo: CSFS

Figure 28: This house has a high risk ofburning during an approaching wildfire.
Modifying the fuels around a homeis critical to reduce the risk of losing
structures during a wildfire. Photo: CSFS

Figure 30: Firefighters were able to savethis house during the 2012 Weber Fire
because the homeowners had a good
defensible space. Photo: Dan Bender, La
Plata County

www.csfs.colostate.edu
This quick guide was produced by the Colorado State Forest Service (CSFS). CSFS programs areavailable to all without discrimination. No endorsement of products or services is intended, nor is
criticism implied of products not mentioned.

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