Establish defensible-space vegetation management around the home
FEMA P-2325 §Wildland-Urban Interface (WUI)Description
Around homes in wildfire-prone areas, vegetation should be managed in concentric defensible-space zones: 0-5 ft 'ember-resistant' (no combustibles, no mulch), 5-30 ft 'lean and green' (low-density, irrigated, fire-resistant plantings), and 30-100 ft 'reduced fuel' (thinned, limbed-up trees). Access routes need separate clearance for emergency response.
Why this exists
Defensible space reduces flame contact, radiant heat, and ember-load on the structure. NFPA + IBHS research underpins the concentric-zone approach; the 0-5 ft zone is the highest-value zone to maintain.
Measurements
| Property | Operator | Value | Unit | Note |
|---|---|---|---|---|
zone1Distance | exact | 5 | ft from structure | Ember-resistant zone (no combustibles) |
zone2Distance | exact | 30 | ft from structure | Lean-and-green zone |
zone3Distance | exact | 100 | ft from structure | Reduced-fuel zone |
Categories
Source
Solver enforcement
Browsable only — the solver does not currently enforce this directive (no spec-level data to check against). This entry exists so the architect personas can cite it in conversation and the user can read what the rule says.
Related directives
- Continuous load path from roof to foundation · HUD RSDG §2.4
- Residential structural reliability targets 1-in-100 to 1-in-1000 annual probability of failure · HUD RSDG §2.5
- Residential floor live load: 40 psf minimum (30 psf sleeping rooms) · HUD RSDG §3.4
- Wind load design uses ASCE 7 basic wind speed for the locality · HUD RSDG §3.6
- Ground snow load for Virginia: 25 psf eastern, up to 40 psf western mountains · HUD RSDG §3.7
Last reviewed 2026-05-11.