Defensible space

Defensible space is the managed band of vegetation and materials around a structure, described in zones measured from the walls and attached decks. The common shape is three bands: Zone 0 at 0–5 feet, kept largely noncombustible; Zone 1 at 5–30 feet, where fire-resistant plants belong, spaced and free of ladder fuels; and Zone 2 at 30–100 feet, thinned rather than cleared. Names and distances differ by document: Colorado's 2025 CWRC calls them Structure Ignition Zones 1, 2 and 3 at the same distances; Prescott's Appendix B uses Immediate, Intermediate and Expanded; Boise requires at least 30 feet of fuel modification plus a five-foot fuel-free area (zone bands).

Who requires it. In California, Public Resources Code 4291 is the defensible-space law a seller documents under Civil Code 1102.19 (AB 38), and the Board of Forestry voted on statewide Zone 0 rules on 19 August 2026, not yet in force at this site's verification. Oregon's State Fire Marshal publishes a homeowner checklist: 100 feet of defensible space or to the property line, vegetation 5 feet from the structure, limbs up to 6 feet on trees over 18 feet (Oregon checklist). IBHS Wildfire Prepared Home and California Safer from Wildfires credit the five-foot zone as a property measure. Firewise USA is community recognition, not a lot rule.

What it is not. Defensible space is not a building code and not a planting list. A plant this site rates fire-resistant belongs in Zone 1, never Zone 0 (why), and the plant directory rates species by the published evidence for the outer zones. The landscaping hub holds the sourced rules for the first five feet.