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.
Defensible space will 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 using fire-resistant construction materials and techniques. Creating an area of 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.
Defensible Space Zones
Three "Home Ignition Zones" make up the required 100 feet of defensible space. The Immediate Zone begins on the outside of your house and extends about 5-6 feet away. The Intermediate Zone is within 30 feet of the house. The Extended Zone 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. Specific recommendations for each zone are described below.
Note that Cal Fire and many local fire agencies use a simplified zone concept where "Zone 1" would include the Immediate and Intermedaite Zones, and "Zone 2" equates tot he Extended Zone. All recommendations within these zones are identical. FIRESafe MARIN and the NFPA Firewise USA Program break the zones down further to provide added detail.
Zone 1 (Immediate)
The Immediate 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 most aggressively maintained for fire resistance.
- Remove any combustible outdoor furniture.
- Replace jute or fiber door mats with fire resistant materials.
- Clean all fallen leaves and needles regularly. Repeat often during fire season.
- Remove ALL fire-prone plants, and choose only fire-resistant varieties. Irrigate regularly.
- Remove tree limbs that extend into this zone. Fire-prone trees should be aggressively pruned or ideally, removed.
- Provide adequate spacing between all plants.
- Do not store firewood, lumber, or combustibles here, even (especially) under decks or overhangs. Move stored combustibles inside, or at least 30' away from structures.
- Use only fire resistant mulches. 'Gorilla Hair" or similar shredded bark should be removed in this zone. Composted mulch and large bark and chips may be OK.
Zone 1 (Intermediate)
The Intermediate Zone from 5' to 30' out from buildings, structures, decks, etc.
- Remove all dead plants, grass, and weeds (vegetation).
- Remove dead or dry leaves and pine needles from your yard, roof and rain gutters.
- Trim trees regularly to keep branches a minimum of 10 feet from other trees.
- Remove branches that hang over your roof and keep dead branches 10 feet away from your chimney.
- Relocate wood piles into Zone 2.
- Remove or prune flammable plants and shrubs near windows.
- Remove vegetation and items that could catch fire from around and under decks.
- Create additional separation between trees, shrubs and items that could catch fire, such as patio furniture, wood piles, swing sets, etc.
Zone 2 (Extended)
Extending from 30' to 100' (or more, if required due to steep slopes, nearby vegetation conditions, and/or your local 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.
Check with your local fire department for any additional defensible space or weed abatement ordinances.
The information contained on this page is derived from several print and online sources:
- University of California Publication 8228. Home Landscaping for Fire. 2007. University of California, Davis.
- http://www.readyforwildfire.org/ Wildfire is Coming: Are You Ready. CAL FIRE. 2012.
- Urban Forestry Associates. Ray Moritz, Urban Forester and Fire Ecologist.