Defensible Space

Defensible space is essential to improve your home’s chance of surviving a wildfire.

In UC ANR Publication 8695, Valachovic, Quarles and Swaim describe Defensible space as a “term used to describe actions to take in zones around a home that involve careful selection, location and maintenance of vegetation and other combustible materials on a property. The goal of defensible space is to

  • eliminate pathways for a wildfire to burn directly to the home
  • reduce radiant heat exposures
  • reduce the potential for embers to ignite vegetation and other combustible materials adjacent to the home
  • provide a safe place for fire personnel to defend the home and allow safe routes for evacuation.”

Defensible space is the buffer you create between a building on your property and the grass, trees, shrubs, or any wildland area that surround it.  Defensible space will help slow or stop the spread of wildfire and protect your home from catching fire – either from direct flame contact or radiant heat. Defensible space is also important to help protect firefighters when they are defending your home. 

Your home may be the most valuable investment you ever make. If you live in a high-risk fire hazard area, protect against the chance of losing that investment by creating defensible space and hardening your home with fire-resistant construction materials and design.  

Creating defensible space does not mean you need a ring of bare dirt around your home! Through proper planning, you can have both a beautiful landscape and a fire safe home.

Valachovic, Quarles and Swaim further state that “implementing an effective defensible space strategy requires that overgrown, dense, or unmaintained vegetation creates significant vulnerabilities and that it can enable fire to burn to the home through several fire-spread scenarios, including ember ignition of vegetative debris on the ground and ember ignition of vegetative debris on roofs. Ignition of outbuildings can also occur due to emergency ignition of nearby combustibles. These fire=spread scenarios can also result in radiant heat or flame contact exposures to the home. Additional fuel reduction strategies, such as reducing vegetation along access routes or limbing trees to allow for easier passage of fire equipment, should be implemented to create safe routes for evacuation.”

Defensible Space Zones

Fire Safe Marin recommends homeowners utilize the “Home Ignition Zone” concept to make up the required 100 feet of defensible space. 

Three zones make up the required 100 feet of defensible space:

  • Zone Zero extends zero to five feet from structures, including the building itself, and should be completely free of combustibles. 
  • Zone 1 begins five feet from your house and extends 30 feet away. The most aggressive clearance is required closest to the structure.
  • Zone 2 lies beyond the home defense zone, extending at least 100 feet from the house or to your property line. Greater defense zone widths may be necessary if your home is on a steep slope or in a windswept exposure.

The Access Zone, Zone 3, is adjacent to roads and driveways, fourteen feet overhead and ten feet from the edge of the roadway. 

Specific recommended actions for each zone are described here.

The Law

Defensible space is required by law! Check with your local fire department for any additional defensible space or weed abatement ordinances.

FAQ

Our property line is 10 feet from our home and there are several properties adjoining, all with overgrown vegetation.  Do our neighbors have a responsibility to maintain defensible space on their land adjoining us?

Some Marin fire agencies have adopted fire code language that may require neighboring properties to provide some vegetation clearance to protect their neighbor’s home.  State law does not necessarily require this.  Fire Safe Marin encourages neighbors to work together and to grant permission to their neighbors to work on adjoining properties to gain defensible space.  Contact your local fire department for an interpretation of the fire code that applies to your neighborhood.

You can find more information about codes and regulations related to tree hazards and the responsibility of neighbors to maintain their property here.

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The information contained on this page is derived from several print and online sources:

  • University of California Publication No. 8695, Reducing the Vulnerability of Buildings to Wildfire Vegetation and Landscaping Guidance, 2021 (UC Agriculture and Natural Resources)
  • University of California Publication No. 8228, Home Landscaping for Fire,  2007 (University of California, Davis)
  • Website http://www.readyforwildfire.org, Wildfire is Coming: Are You Ready , 2012 (California Department of Forestry and Fire Protection (CAL FIRE)) 
  • Urban Forestry Associates, Ray Moritz, Urban Forester and Fire Ecologist