Wildfire Ember Exposure & Defensible Space Calculator
Assess your home's vulnerability to wildfire embers and get defensible space recommendations.
Last reviewed: June 2026Structure Materials
Vegetation & Terrain
Additional Risk Factors
Ember Exposure Score
Component Vulnerability Breakdown
| Component | Rating | Score (0-10) | Risk Level |
|---|
Top Mitigation Priorities
Quick Wins
Defensible Space Zones
How the wildfire defensible space score works
The Wildfire Defense Calculator is a preparation checklist and scoring model for common home ignition risks. It focuses on ember exposure because many structures ignite when embers collect in gutters, vents, decks, fencing, mulch, or vegetation near the building. The score combines structure factors such as roof class, siding, deck material, vent screening, windows, gutters, and attached fencing with site factors such as nearby vegetation, fuel density, slope, wind exposure, woodpiles, outbuildings, propane tanks, and overhead power lines.
The output is not a fire-spread forecast and it does not know your address, fire history, evacuation route, insurance rules, or local code. Treat it as a self-audit: a way to identify obvious weak points before you request a local inspection, talk with your fire department, or prioritize weekend mitigation work.
What to do with the results
- Start with Zone 0: The first 0 to 5 feet around the structure is usually the highest-leverage area. Keep it clear of leaves, mulch, firewood, combustible furniture, and stored items.
- Check ember entry points: Vents, gutters, roof edges, deck gaps, and unscreened openings often deserve attention before cosmetic landscaping changes.
- Separate fuels: Move woodpiles, propane exposure, combustible fencing, dense shrubs, and outbuildings away from the structure where practical.
- Account for slope and wind: Steeper slopes and strong prevailing winds increase the need for spacing, pruning, and fuel reduction.
- Repeat seasonally: Leaves, needles, dry grass, and new storage habits can change the score even when the house itself has not changed.
Example interpretation
A home with Class A roofing, metal gutter guards, screened vents, non-combustible siding, and clean Zone 0 may score low even in a moderately vegetated area. The same vegetation next to wood siding, open vents, debris-filled gutters, and a wood fence attached to the house can push the score much higher. The value of the calculator is seeing which individual inputs drive the score so mitigation is specific instead of vague.
During an active wildfire, follow official evacuation orders and emergency instructions. This page is for preparation and maintenance planning, not real-time safety decisions.