Assessment · Cal Wildfire Defense
Structure Hardening Assessment
From $499
Your defensible space matters. So does what it’s protecting.
The Structure Hardening Assessment evaluates your home or building against the six primary ways fire enters and ignites a structure. Because cleared land and a fire-resistant structure are not the same thing — and you need both.
What it is
Defensible space buys time. A hardened structure uses it.
Most wildfire preparation focuses on the land around the structure — clearing vegetation, managing fuel loads, establishing zone boundaries. That work is essential. But research consistently shows that the majority of homes lost in wildfires don’t ignite from direct flame contact. They ignite from embers.
Embers travel ahead of the fire front — sometimes miles ahead under Santa Ana conditions — and they look for places to land and find something to burn. An unscreened attic vent. A combustible deck with debris underneath. A wood fence connected directly to the house wall. A gap in the siding. These are the entry points that matter, and they’re what the Structure Hardening Assessment is designed to find.
A cleared property with an ember-vulnerable structure can still burn.
The Structure Hardening Assessment evaluates the structure as the fire target it is — identifying every vulnerability before fire season gives them a chance to matter.
This is a professional evaluation, not a building inspection. CWD does not certify structural compliance or issue building code determinations. What we provide is a fire-informed assessment of your structure’s ignition vulnerabilities and a prioritized list of what to address.
Who it’s for
A natural next step after your Risk Walk — or a standalone service.
The Structure Hardening Assessment is the right choice if:
- You’ve completed a Property Fire Risk Walk and want a complete picture — vegetation management and structure vulnerability addressed together.
- Your insurance carrier is asking specific questions about your home’s construction, materials, or vent screens.
- You’re planning renovation or construction work and want to incorporate fire-resistant materials and decisions from the start rather than retrofit later.
- You’ve done defensible space work and want to know what the next layer of protection looks like.
- You’re in a high fire hazard severity zone and want to understand the full picture of your property’s exposure — land and structure together.
What happens
Six ignition pathways. Evaluated in priority order.
Fire research has identified six primary pathways through which structures ignite during wildfires. The Structure Hardening Assessment evaluates each one systematically, in the order that matters most — starting with the pathways responsible for the highest proportion of structure losses.
1. Vents and openings — highest priority
Attic vents, crawlspace vents, and soffit vents are the most common ember entry point. We evaluate screen mesh size (the standard is 1/16 to 1/8 inch corrosion-resistant metal — not plastic, which melts), any openings greater than 1/8 inch, and whether any CAL FIRE-listed ember-resistant vents are installed. A single unscreened vent is sufficient for an ember to enter and ignite the interior.
2. Deck and attached structures
Combustible decks trap embers underneath and radiate heat to the structure wall. We evaluate deck surface material, what’s under the deck and whether it’s enclosed, whether a 5-foot non-combustible perimeter exists, and the deck-to-wall junction. A wood deck fire is often the mechanism by which an ember ignition becomes a full structure loss.
3. Fence connections to the structure
A wood fence connected directly to the house is a fire pathway from the wildland to the structure wall. We document all fence connections within 5 feet of the structure and whether a non-combustible break exists. This is one of the most common and most easily remedied vulnerabilities we find.
4. Windows and glazing
Single-pane windows can fail from radiant heat before the fire front arrives, opening the structure to ember entry. We document glazing type, frame material, and the condition of any exterior shutters or screens — particularly on elevations facing the primary fire approach direction.
5. Exterior siding and wall assemblies
Gaps in siding greater than 1/8 inch allow flame and ember entry. We evaluate siding material and condition, the lowest course from grade, and base flashing. Fiber cement, stucco, and masonry are meaningfully more resistant than wood siding — this section identifies where the gap matters most.
6. Roofing system
Roofing material class, eave condition, ridge and hip flashing, and debris accumulation in valleys are all evaluated. Class A roofing — tile, metal, or fiberglass shingles — with enclosed eaves is the standard. This is the most expensive system to address, which is why it appears last in the priority order.
What you get
A prioritized report you can act on.
The Structure Hardening Report
A written document covering current condition and vulnerabilities across all six ignition pathways, prioritized by fire risk. For each identified vulnerability: what we found, why it matters, and what to do about it — with specific material and upgrade recommendations. Also includes a summary of how the structure’s current hardening level interacts with the property’s defensible space work, because the two are a system. If you’ve had a Risk Walk, the report connects directly to your Walk Summary. Produced within 48 hours of the assessment.
The report is written to be useful — not just to understand the problem, but to brief a contractor, support an insurance conversation, or make informed decisions about renovation priorities.
What comes next
Structure hardening is a spectrum, not a switch.
Not every vulnerability identified in the assessment requires immediate action or full replacement. The report prioritizes by impact — the changes that most reduce your risk of structure ignition, starting with the least expensive and most effective. Many of the highest-priority items (vent screens, fence breaks, Zone 0 debris clearance) are low-cost fixes with significant impact.
For customers ready to go further:
Want to know what your structure’s exposure looks like?
Call CWD to schedule a Structure Hardening Assessment — standalone or paired with a Property Fire Risk Walk for a complete picture of your property’s fire exposure.
Call CWD to Schedule → 619-949-3814 Not ready to call? Reach us by email or through our contact page → Want to understand the terminology first? Visit our Wildfire Education site →