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Day 4: Expand Your Defensible Space

A simple, 7 day guide to improving your home and family's wildfire preparedness with easy, inexpensive tips.

Day 4: Expand Your Defensible Space

Defensible space is essential to improve your home’s chance of surviving a wildfire.  It’s the buffer you create between a building on your property and the grass, trees, shrubs, or any wildland area that surround it.  This space is needed to slow or stop the spread of wildfire and it protects your home from catching fire – either from direct flame contact or radiant heat.  Defensible space is also important for the protection of the firefighters defending your home, and it's required by law!

Creating an area of defensible space does not mean you need a ring of bare dirt around your home.  It does not mean you need to remove all of the trees on your property.  It does, however require some planning and upkeep.  With proper planning, you can have both a beautiful drought resistant, low water landscape and a fire safe home.

The defensible space concept is simple: that trees should be limbed up, spaced out, and kept further from your house; shrubs can be closer, but should be kept low and spaced; bedding plants and lawns may be nearest the house.  The use of "hardscaping" like retaining walls, pathways, and clean space near the home will beautify your property and add the finishing touch on a well planned defensible space.

Plants and Defensible Space

Our goal is to help homeowners protect their homes in an hour or less each day.  One simple way to achieve this, is to add spacing to your landscaping plants by removing a few plants.  Look for hazardous "fire-prone" plants on our list, and start by removing these. Removing half of the plants from an overgrown garden, and covering the space with fire resistant mulch (compost or 1/2" or larger bark works well) can cut your irrigation water use in half, improve the health of remaining plants, and dramatically slow the spread of fire. Do not use combustible bark mulch within 5' of structures. Ensure that remaining plants are on our Marin county specific "fire safe" plants list.  

 A simple drip irrigation system can be added to save even more water, and improve the health of remaining plants.  Careful, water-wise irrigation and mulch will improve water retention in the plants, which makes your remaining landscape even more resistant to fire. Use plants that encourage pollinators and provide habitat, while providing a fire re=silient landscape.

Defensible Space Zones: 0'-100'

These zones make up the required 100 feet of defensible space. Specific recommendations for each zone are described below and pertain to all Marin jurisdictions in the Wildland Urban Interface. Some cities and fire departments may have slightly more stringent requirements - FIRESafe MARIN recommends taking the most comprehensive approach possible, even if your community does not require it.

FIRESafe MARIN defensible space diagram

ZONE 0: 0'-5'

Zone Zero, sometimes referred to as the "Immediate Zone" is the area nearest your house, 0'-5', including the surfaces of the structure itself.  There should be ZERO combustibles in this zone!  Take steps to 'harden" your home with fire and ignition resistant materials and design!

This zone extends 0'-5' from your house.  It's the area closest to your house, including plants, decks, outdoor furniture, and the outside walls and coverings.  This area is most vulnerable and should be more aggressively maintained for fire resistance.

  • Remove combustible outdoor furniture.  Replace with metal or non-combustible varieties.
  • Replace jute or natural fiber doormats with heavy rubber or metal grates.
  • Remove or relocate all combustible materials including garbage and recycling containers, lumber, trash, and patio accessories.
  • Clean all fallen leaves and needles.
  • No vegetation is recommended within 5’ of any structure.
  • Remove tree limbs that extend into this zone.  Fire prone tree varieties should be removed if they extend into this zone.
  • Do not store firewood, lumber, or combustibles here, even (especially) under decks or overhangs.  Move stored combustibles inside or at least 30’ from any structure.
  • Use only inorganic, non-combustible mulches such as stone or gravel.
  • Hardscaping is strongly recommended around the base of structures.

ZONE 1: 5'-30'

Zone 1, sometimes referred to as the "Intermediate Zone" extends from your house's exterior walls to a distance of 30'.  The "Lean, Clean, and Green" zone.

This extends 0'-30' out from buildings, structures, decks, etc, and overlaps the Home Ignition Zone described above.

  • Remove all dead grasses, weeds, plants, & foliage. 
  • Remove all fallen leaves, needles, twigs, bark, cones, and small branches. 
  • Remove “Gorilla Hair” or shredded bark mulch.
  • Use only compost or heavy bark mulch to maintain soil moisture, or for erosion control.
  • Choose only fire resistant plants, and keep them healthy and well irrigated.
  • Remove fire-prone plants.
  • Provide spacing between shrubs, at least 2 times the height of the mature plant. Add space on steeper slopes.
  • Trim trees to remove limbs 6’ to 10’ from the ground.
  • Remove branches that overhang your roof or within 10’ of chimneys. 
  • Move firewood & lumber out of Zone 1, or cover in a fire resistant enclosure.
  • Remove combustibles around and under decks and awnings.
  • Clear vegetation around fences, sheds, outdoor furniture, play structures.
  • Outbuildings and LPG storage tanks should have at least 10’ of clearance.
  • Maintain regularly, focusing on the areas closest to structures.

ZONE 2: 30'-100'

Zone 2, sometimes referred to as the "Extended Zone," extends from 30' to at least 100' - more Defensible Space may be required based on topography, vegetation, or building construction (for example, if you live on a hill, in a drainage, or an area surrounded by unusually dense or flammable vegetation, or have a wood shake roof, 150' or more may be required).  California and local laws usually do not require you to create Defensible Space on property you don't own (check with your local fire agency if you're not sure).  Work with your neighbors to gain permission to clear defensible space on their property if it will help protect your home!

Extending from 30'-100' or to your property line at a minimum (you may be required to provide more clearance due to steep slopes, nearby vegetation conditions, and/or other conditions identified by the fire department).  This zone should include at a minimum:

  • Cut or mow annual grass down to a maximum height of 4 inches.
  • Create horizontal spacing between shrubs and trees. (See diagram)
  • Create vertical spacing between grass, shrubs and trees. (See diagram)
  • Remove fallen leaves, needles, twigs, bark, cones, and small branches. However, they may be permitted to a depth of 3 inches if erosion control is an issue.
  • Remove all piles of dead vegetation.

ZONE 3: ACCESS ZONE: 0'-10'

Zone 3, the "access" zone, extends from 0' to at least 10' horizontally from the edge of roads and driveways, and 14' overhead.

Property owners are responsible for vegetation adjacent to roads and driveways.  Access roads are critical for evacuation and first responder access. Maintenance is required year-round.

  • Property owners are responsible for vegetation adjacent to roads and driveways.
  • Clear vegetation 14’ overhead and 10’ from sides of roads and driveways in the same manner as Defensible Space Zone 1. 
  • Maintain 12’ of unobstructed pavement for passage of vehicles. 
  • Within this zone, plantings shall be fire resistant and must not extend into the roadway.
  • 14’ of clearance is required above the roadway for emergency vehicle access.
  • Address numbers must be clearly visible from the road, with at least 4” numbers on a contrasting background.  Reflective or lighted numbers are best.
  • Create vertical spacing between shrubs, and lower tree limbs.  Cut all grasses.

* Check with your local fire department for any additional defensible space or weed abatement ordinances. 

Fire Safe Landscaping

Defensible Space requires the installation and maintenance of fire resistant landscaping, sometimes referred to as "firescaping."  It is important to remember that a fire safe landscape isn't necessarily the same thing as a well-maintained yard.   A fire safe landscape uses hardscaping features and fire resistant plantings that are strategically placed to resist the spread of fire to your home.

The good news is, you don't need a lot of money to make your landscape fire safe. And you will find that a fire safe landscape can increase your property value and conserve water while beautifying your home.

Learn more about Fire Safe Landscaping practices and materials here...

Hardening Structures Against Wildfire

During a wildfire, tiny burning embers can fly far ahead of the fire, sometimes igniting homes a mile or more away from the fire itself.  A wildfire-safe home must be resistant to ignition from these flying embers, so that even if the flames do not reach your home, it will be able to withstand exposure to embers that may have been blown a mile or more in front of a wildfire. To provide maximum wildfire protection for your home, a combination of near-home vegetation management, appropriate building materials, and related design features must be used.

Learn more about fire resistant construction practices and materials here...

FIRESafe MARIN   |   P.O. Box 2831  |   San Anselmo, CA 94979   |   info@firesafemarin.org

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