Defensible Space Zone 0 Calculator
The 0–5 ft band right against your house — Zone 0 — is where embers do the most damage, so it should be noncombustible: gravel, rock, or hardscape, not bark mulch or plants. Enter your home footprint to size that ember zone and get the gravel quantity and cost, plus what belongs in each defensible-space zone. It's a planning estimate — confirm the rules that apply to you with your local fire authority.
638sq ft ember zone
Bags or bulk for the gravel?
For this size, bulk usually wins. Gravel is heavy — a half-ton pickup carries only ~1 cu yd safely.
In the 0–5 ft zone, use noncombustible cover:
✓ Gravel, crushed rock, decomposed granite, pavers, concrete, or bare mineral soil.
✗ No bark/wood mulch, rubber mulch, or plants/grass against the wall — and no wood fence or gate touching the house in the first 5 ft.
- Zone 0 (0–5 ft) is coming, not law yet. California approved the ember-zone rule in 2026; it's in final state review and phases in over the next few years for existing homes (some local rules, e.g. San Diego, may already apply). Get ahead of it — but check your local fire authority for what applies to you now.
- This is a materials planning estimate — gravel tonnage varies with rock size, compaction, and base prep. Confirm with a supplier or landscape pro; the tool doesn't measure your actual lot.
- It doesn't make a home "compliant" or guarantee any insurance outcome. Compliance is set by your local fire authority and the CAL FIRE Fire Hazard Severity Zone map (PRC 4291 = 100 ft in high-hazard areas).
Planning the fire-smart yard?
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Building a fire-smart, low-water yard? Price gravel, mulch, and more in the Material Calculator, plan the planting in the Lawn-Conversion Planner, or see the whole picture on the Resilient California Yard hub.
The three defensible-space zones
In California's high fire-hazard areas, PRC 4291 requires 100 feet of defensible space. It's worked in three zones, innermost first: Zone 0 (0–5 ft) — the ember-resistant band this calculator sizes, kept noncombustible; Zone 1 (5–30 ft) — lean, clean, and green, with spaced plants, no dead vegetation, and combustible mulch kept shallow and broken up; and Zone 2 (30–100 ft) — reduced fuel, mowed grass, and spaced tree canopies. Zones 1 and 2 are mostly spacing and clearing (labor), which is why the materials estimate here focuses on the Zone 0 ground cover.
Defensible space & Zone 0 — FAQs
What is Zone 0 and what can I put there?
Zone 0 is the ember-resistant band from 0 to 5 feet around your home — the highest-priority defensible-space zone, because wind-blown embers pile against the wall. California fire guidance calls for noncombustible ground cover here: gravel, crushed rock, decomposed granite, pavers, concrete, or bare mineral soil. Keep out bark and wood mulch, rubber mulch, plants and grass against the wall, stored firewood or furniture, and wood fences or gates that touch the house within the first 5 feet.
Is the Zone 0 rule law yet?
Not statewide, yet. California's Board of Forestry approved the Zone 0 (0–5 ft ember-resistant) regulation in 2026; it's in final state review and will phase in over the next few years for existing homes, with new construction first. Some local jurisdictions (San Diego, for example) already apply it to new permits, and it's smart to get ahead of it regardless. Check your local fire authority for what applies to your property now — this tool helps you plan, it doesn't determine compliance.
How much gravel do I need for the 0–5 ft zone?
Multiply your home's perimeter by 5 feet to get the band area, subtract doorways, driveways, and anything already hardscaped, then apply a depth of about 2–3 inches of gravel or rock over non-woven landscape fabric. The calculator does this for you and converts the area into cubic yards, tons, and bags — and compares buying it in bags versus bulk delivered. It's a materials planning estimate; confirm quantities with a stone supplier, since tonnage varies with rock size and compaction.
Do I need defensible space, and how far out?
If your home is in a State Responsibility Area or a High or Very High Fire Hazard Severity Zone, California's PRC 4291 requires 100 feet of defensible space (or to your property line). Zone 0 is the innermost 0–5 ft, Zone 1 is 5–30 ft (lean, clean, green), and Zone 2 is 30–100 ft (reduced, spaced fuel). Look up your address on the CAL FIRE Fire Hazard Severity Zone map, and confirm the specifics with your local fire authority.
Are drought-tolerant plants fire-safe near the house?
Not automatically — and it's the catch most low-water plant lists skip. Fire-resistant is not fireproof, and several classic drought-tolerant plants (juniper, rosemary, eucalyptus, pampas grass) are actually highly flammable. Nothing combustible belongs in the 0–5 ft zone regardless of how little water it needs. Save the low-water plants for Zone 1 and beyond, spaced and maintained.