Wildland Fuel Reduction Area:

Dead vegetation should be removed from the wildland fuel reduction area.

This area usually lies beyond the residential landscape area and is where sagebrush, cheatgrass, pinyon and other wild plants grow. Within this area:

Thin dense trees to create a separation between them.
  • On flat to gently sloping terrain, dense trees should be thinned to provide a separation of 10 feet between braches.
  • Remove all dead vegetation (dead shrubs, dried grass, fallen leaves, etc.).
  • Thin out thick shrubs and trees to create a separation between them.
  • Prevent ladder fuels by removing low tree branches, and removing or pruning any shrubs under the tree.
Ladder fuels allow a ground-level fire to reach the trees

Lean, Clean and Green Area:

This home's lean, clean and green area helped protect it from wildfire.

For a distance of at least 30 feet from the home, there should be a Lean, Clean and Green Area. Lean indicates that only a small amount of flammable vegetation, if any, is present within 30 feet of the house. Clean means there is no accumulation of dead vegetation or flammable debris within the area. Green denotes that plants located within this area are kept healthy, green and irrigated during fire season. For most homeowners, the Lean, Clean and Green Area is the residential landscape. This area often has irrigation, contains ornamental plants and is routinely maintained.

Noncombustible Area:

Rock mulches are a good choice for the noncombustible area.

Create a Noncombustible Area at least 5 feet wide around the base of your home. This area needs to have a very low potential for ignition from flying embers. Use irrigated herbaceous plants (lawn, ground cover and flowers), rock mulches, or hard surfaces (concrete, brick and pavers) in this area. Keep it free of woodpiles, wood mulches, dead plants, dried leaves and needles, flammable shrubs (sagebrush and juniper) and debris.

Defensible Space Calculator:

The recommended distance for an effective defensible space is not the same for every home. It varies depending on the dominant vegetation surrounding the home and steepness of slope. Follow the steps below to determine the recommended distance for your home.


Select the percent slope that best describes your property:
Flat to Gently Sloping 0-20%
Moderately Steep 21-40%
Very Steep +40%

Select the type of vegetation that best describes the wildland plants growing on or near your property:
Wildland grasses, weeds and widely scattered shrubs with grass understory
Shrub-dominant areas (sagebrush, bitterbrush, Manzanita, etc.) and pinyon-juniper
Forest trees (Jeffrey pine, White Fir, etc.) If there's a substantial grass or shrub understory, select the appropriate option above

Click "Calculate" to find the number of recommended feet for your defensible space.

Five Steps to Creating an Effective Defensible Space: Introduction

Make your house safe for firefighters to defend.
A homeowner can have both an effective defensible space and an attractive landscape.

The term defensible space refers to the area between a house and an oncoming wildfire where the vegetation has been managed to reduce the wildfire threat and allow firefighters to safely defend the house. In the event that firefighters are not available, defensible space also improves the likelihood of a home surviving without assistance.

Unfortunately, when some homeowners hear the term defensible space, they envision a large expanse of bare ground surrounding their home. While bare ground is certainly effective at increasing home survivability, it can detract from the home's aesthetics and contribute to soil erosion. It is also unnecessary.

Click on each of the five steps to create an effective defensible space.

Step 1: Know Your Distance

The size of the defensible space is usually expressed as a distance extending outward from the house in all directions. The recommended distance is not the same for every home. It varies depending on the dominant vegetation surrounding the home and steepness of slope. Use the Defensible Space Calculator to determine the right space for your home.

Defensible space distance is measured from the base of the house, extending outward.

Once the recommended distance for defensible space is known, mark it by tying strips of cloth or flagging to shrubs. This becomes the Defensible Space Zone.

If the Defensible Space Zone exceeds your property boundaries, seek permission from adjacent landowners before doing work on their property. It is important to note that the effectiveness of the Defensible Space Zone improves when entire neighborhoods implement defensible space practices.

Step 2: Remove the Dead

Within the recommended Defensible Space Zone, remove:

  • Dead and dying trees.
  • Dead native and ornamental shrubs.
  • Dead branches.
  • Dead leaves, needles and twigs that are still attached to plants, draped on live plants or lying on the ground within 30 feet of the house.
  • Dried grass, weeds and flowers.

Remove all dead trees from within the defensible space area.
Remove all dead ornamental shrubs, especially juniper.
Once wildflowers dry out and turn brown, remove them.

Step 3: Create Separation

Within the Defensible Space Zone, native trees and shrubs, (Jeffrey pine, pinyon, juniper and sagebrush) should not occur in dense stands. Dense stands of trees and shrubs pose a significant wildfire threat. Thin dense tree and shrub stands to create more space between them.

Sagebrush, other Shrubs, Pinyon and Juniper

On flat to gently sloping terrain, individual shrubs or small clumps of shrubs within the Defensible Space Zone should be separated from one another by at least twice the height of the average shrub. For homes located on steeper slopes, the separation distance should be greater.

For example, if the typical shrub height is 2 feet, then there should be a separation between shrub branches of at least 4 feet. Remove shrubs or prune to reduce their height and/or diameter. In most instances, removing big sagebrush is the preferred approach. It is a very flammable plant, is easily removed, does not resprout and is typically abundant.

Jeffrey Pine and White Fir

Dense stands of trees are vulnerable to insects and disease
On flat ground, provide a separation of at least 10 feet between Jeffrey pine and white fir.
On flat to gently sloping terrain, Jeffrey pine and white fir should be thinned to provide an average separation between canopies of at least 10 feet. For homes located on steeper slopes, the separation distance should be greater. When selecting trees for removal, consider cutting unhealthy, damaged or weak trees.

Step 4: No Ladder Fuels

Remove ladder fuels to a height of 10 feet.

Vegetation that can carry a fire from low-growing plants to taller plants is called ladder fuel. Lower tree branches should be removed to a height of at least 10 feet.

Shrubs and trees growing under the drip line should also be removed. Irrigated, well-maintained lawns and flowerbeds, as well as low-growing ground-covers can be present under the tree's drip line as long as they would not allow a fire to ignite the tree.

Removal of tree branches should not exceed one third of the total tree height. Removing more than this can be detrimental to tree health.
A burning juniper ignited the lower branches of this pine.

Step 5: Make it Lean, Clean and Green

There are two goals for the Lean, Clean and Green Area. The first goal is to eliminate easily ignitable fuels, or kindling, near the house. This will help prevent embers from starting a fire in your yard. The second goal is to keep fire intensity low if it does ignite near the house.

By proper management of the fuels near the house, a fire would not be able to generate enough heat to ignite the home.

For most homeowners, the Lean, Clean and Green Area is also the residential landscape. This area often has irrigation, is planted with ornamental vegetation and is regularly maintained.

Lean, Clean and Green Area Tips

Remove most or all flammable wildland plants, including big sagebrush, bitterbrush, rabbitbrush, cheatgrass, pinyon, juniper and manzanita. If you wish to retain a few of these as specimen plants, make sure they are free of dead wood and leaves, pruned to reduce the amount of fuel and separated from adjacent brush fields.

Select less flammable plants for the home landscape. Some rules of thumb in selecting landscape plants for the Lean, Clean and Green Area are:

  • Shorter plants, less than 2-feet tall, are better choices than taller plants.
  • Green, herbaceous plants (grass and non-woody flowers) are better choices than shrubs and trees.
  • Deciduous shrubs and trees are better choices than evergreen types. Avoid planting juniper, mugo pine and arborvitae.

Emphasize the use of hard surfaces (concrete, asphalt and brick). Within 30 feet of the house, do not use wood mulches in a widespread manner, and do not use rubber mulches.

Clear flammable vegetation away from propane tanks.

Clear all flammable vegetation from within 10 feet of the propane tank.

Remove tree limbs that are within 10 feet of the chimney, touching the house or deck, within 6 feet of the roof or encroaching on power lines.

A well maintained lawn is a good choice for the Lean, Clean, and Green Area.

Create a noncombustible area at least 5-feet wide around the base of the house. Emphasize the use of irrigated herbaceous plants, (lawn, ground covers and flowers). Also use rock mulches and hard surfaces.

Maintenance

Maintaining a defensible space is an ongoing activity. Plants grow back and flammable vegetation needs to be routinely removed and disposed of properly. Before each fire season, re-evaluate your property using the previous five steps and implement the necessary defensible space recommendations.

Step 6: Maintain the Defensible Space Zone.

The last step to creating defensible space is maintenance. Maintaining a defensible space is an ongoing activity. Plants grow back and flammable vegetation needs to be routinely removed and disposed of properly. Before each fire season, reevaluate your property using the previous five steps and implement the necessary defensible space recommendations.

The defensible space zone needs to be maintained on a regular basis.