Defensible Space Matters

What Is Defensible Space?

Defensible space is the area between a house and an oncoming wildfire where the vegetation has been modified to reduce the threat of fire. The aim is to reduce the intensity of the wildfire as it nears a home. This is better referred to as the home ignition zone because the home must be prepared to stand on its own if firefighters are overwhelmed and unable to defend it.

What Defensible Space Can Do For You

A retired firefighter created an extensive area of defensible space around his rebuilt home near the epicenter of the 1991 Oaklanf firestorm.

A retired firefighter created an extensive area of defensible space around his rebuilt home near the epicenter of the 1991 Oakland firestorm.

Defensible space can:

  • Give you time to evacuate safely
  • Provide firefighters the opportunity to effectively defend your house
  • Encourage firefighters to consider your house salvageable
  • Increase the odds your home may survive on its own when firefighting sources are overwhelmed

Seven Steps to Create Defensible Space

You can create defensible space in seven easy steps.

1. Determine your effective defensible space

Consider property lines, slope, wind direction, existing features and vegetation

2. Provide for driveway clearance

Create 10 feet of horizontal clearance on both sides of the driveway and 15 feet of vertical clearance.

3. Make it lean, clean and green

Create a lean, clean, and green area extending 5-30 feet from the house. Eliminate kindling near the house to protect against embers. Manage vegetation so that a fire in this zone won’t be able to generate enough heat to set your home on fire by conduction.

4. Remove dead vegetation

Dead vegetation is particularly dangerous and includes dead and dying standing trees, recently fallen trees, dead native and ornamental shrubs, dead branches; and dried grass, weeds and flowers.

laddering of trees creates a buffer zone

An example of defensible space at the top of a steep slope where erosion is a concern. Note the separation between groups of tree crowns that soften the rain and provide fog drip. Ladder fuels were removed but their roots left intact. A mixture of naturally occurring native plants serving as ground cover has been preserved.

5. Remove ladder fuels

Pay particular attention to flammable ground fuels under bushes and trees. Irrigated, well- maintained lawn and flower beds, as well as low-growing native ground covers, can be kept under a tree’s drip-line.

6. Create a separation between trees and shrubs

Thin stands of grasses, brush and trees to create a mosaic with spaces between them to break up the continuity of fuels. Options vary greatly depending on the steepness of the slope, the frequency of fog drip, and whether the slope is northeast or southwest facing.

7. Maintain your defensible space

Maintaining the defensible space is an ongoing, year-round activity that will vary significantly from year to year depending on the weather. Plants grow, and flammable vegetation needs to be routinely removed and disposed of properly. Be the steward of your own property.