WILDFIRE HOME TOOL · GEOMETRY + MATERIALS
Wildfire Zone 0 Calculator
Measure the immediate band around a building. Calculate gross and net area, inner and outer perimeter, then translate the geometry into gravel or paver planning quantities.
01 · MEASUREMENT SYSTEM
02 · FOOTPRINT METHOD
03 · OUTPUT
A = (L + 2D)(W + 2D) − LWRectangular outer footprint minus building footprint.CALCULATED ZONE
74.3 m² gross band area
ORDERING ESTIMATE · INCLUDES 10% ALLOWANCE
WHAT THE NUMBER REPRESENTS
Geometry first. Materials second.
The result is a planning quantity for the selected footprint. It does not identify utilities, drainage, access, property boundaries, decks, fences, combustible attachments or local construction requirements.
Zone 0 is not a universal legal term. California uses it for the first five feet around a structure and attachments. Other jurisdictions use different distances, terminology and requirements.
TRANSPARENT METHOD
Every assumption stays visible.
Change band depth, adjustments, layer thickness, material density, paver dimensions and ordering allowance. The calculator does not hide regional prices or contractor assumptions.
(L + 2D)(W + 2D) − LWIncludes the square corner areas of the outer rectangle.
P × D + adjustmentA planning approximation. Measure or add irregular corners and projections separately.
net area × layer depthMass uses your editable bulk-density assumption.
net area ÷ paver areaThe selected waste allowance is added before rounding up.
Use the result responsibly
CAL FIRE describes Zone 0 as the first 0–5 feet around structures and attachments and recommends ember-resistant treatment. Material selection, installation details and applicable requirements still need site-specific review.
This calculator does not certify compliance, predict structure survival or establish a safe distance.
California Board of Forestry: Zones 0, 1 and 2 · CAL FIRE: Home hardening · NIST: WUI building and fire codes
Quick answers
Why can I change the five-foot depth?
Five feet reflects California’s Zone 0 terminology. Editable depth makes the geometry useful in jurisdictions or project specifications that use a different immediate band.
Why is measured-perimeter mode approximate?
A perimeter alone does not describe corners, recesses, decks or projections. Use the area-adjustment field for measured additions or exclusions.
Is gravel density always 1.6 t/m³?
No. It is only a starting assumption. Aggregate density varies with material, grading, moisture and compaction; use a supplier value when available.