Part 1: Understand fire · Chapter 2

The zones

Defensible space is the cleared and thinned ground around a house. Fire agencies split it into zones by distance from the house.

Zone numbering differs by source. NFPA describes three bands: 0 to 5 feet, 5 to 30 feet, and 30 to 100 feet, with the last one running out to 200 feet ¹. LA County's pages number theirs from the house as Zones 1, 2 and 3, ending at 30, 100 and 200 feet ². This guide calls the first five feet Zone 0, as IBHS does ³, and uses Zone 1 and Zone 2 for NFPA's next two bands.

Zone 0: 0 to 5 feet

This is the house itself and the five feet around it. NFPA calls it the immediate zone and defines it as a noncombustible area ¹. IBHS research found that removing everything that burns from these five feet is the most effective defensible space action a homeowner can take ³. Plants here are a problem whatever the species or how wet they are ⁴.

What goes in it:

• Clean roofs and gutters, with 1/8-inch metal mesh over eave and attic vents ¹.
• Nothing against the walls that can burn: mulch, flammable plants, firewood, wood fences, outdoor furniture ¹³.
• Nothing stored under decks or porches ¹.

California's Board of Forestry is writing its own Zone 0 rules under Executive Order N-18-25. For where they stand, see the Board's Zone 0 FAQ, linked from LA County's fuel modification page ⁵. This guide gives no effective date until the rules are final.

Zone 1: 5 to 30 feet

NFPA calls this the intermediate zone. Careful landscaping and breaks in the fuel can decrease fire behavior here ¹.

• Use driveways, walkways and patios as fuel breaks ¹.
• Keep lawns and native grasses mowed to four inches ¹. LA County asks for annual grass at three inches or less in its Zone 1 ².
• Remove vegetation under trees and prune branches up to six to ten feet from the ground ¹.
• Remove woodpiles and debris, and clear vegetation from under large propane tanks ¹².

Zone 2: 30 to 100 feet

NFPA calls this the extended zone. The aim here is to break up the fuel so flames stay smaller and on the ground ¹.

• Remove dead plant and tree material and heavy ground litter ¹.
• Clear vegetation next to sheds and outbuildings ¹.
• In LA County's Zone 2, leave space between trees and shrubs both vertically and horizontally ². Its Zone 3, out to 200 feet, calls for thinning native plants by 30 to 50 percent ².

What LA County requires

The county says 200 feet of defensible space is required ². Its Defensible Space Program declares properties a public nuisance and, where necessary, requires clearance of hazardous vegetation ⁶. The county points to the CAL FIRE viewer for checking whether a parcel is in a Fire Hazard Severity Zone ⁶.

Sources

1. NFPA, "Preparing homes for wildfire." https://www.nfpa.org/education-and-research/wildfire/preparing-homes-for-wildfire (read 2026-11-09)

2. County of Los Angeles Emergency Management, "Preparing for Wildfires." https://ready.lacounty.gov/fire (read 2026-11-09)

3. IBHS, "Noncombustible Zone 0: Minimizing Pathways to Home Ignition." https://ibhs.org/wildfire/noncombustible-zone0-minimizing-pathways-to-home-ignition/ (read 2026-11-09)

4. IBHS, "Vegetation in Zone 0: Amplifying Damage to Structures." https://ibhs.org/wildfire/vegetationinzone0/ (read 2026-11-09)

5. County of Los Angeles Fire Department, "Forestry Fuel Modification." https://fire.lacounty.gov/forestry-fuel-modification/ (read 2026-11-09)

6. County of Los Angeles Fire Department, "Defensible Space Inspection Program." https://fire.lacounty.gov/fire-hazard-reduction-programs/ (read 2026-11-09)