If you own a home in Northern California — or you're about to build one — 2025 is the year the rules changed under your feet. The maps that decide which properties carry fire risk have been redrawn. The codes that govern how a house must be built are about to get stricter statewide. And the gap between a home that survives a wildfire and one that doesn't has never come down to luck less than it does right now. It comes down to how the house was built.
I've been building fire-hardened homes across San Francisco, Marin, and Napa Valley for years — long before the state required it. So let me walk you through what's actually happening, where the risk really lives, and what you should be doing about it.
Why 2025 is a genuine turning point
Three things are converging at once. First, CAL FIRE updated its hazard maps in 2024, expanding the zones across the Bay Area to include neighborhoods that weren't flagged a decade ago. Then, in February and March of 2025, the state released new Fire Hazard Severity Zone maps for Local Responsibility Areas — the cities and towns themselves — and they widened the requirements considerably. Properties that never had to think about fire-resistant construction suddenly do.
Second, and bigger: California Title 24, Part 7 takes effect January 1, 2026, with stricter statewide fire-resistant standards. If you're planning a build or major remodel, this is no longer a future concern — it's the code your permit will be reviewed against.
Third, the technical backbone of all of this is CBC Chapter 7A, which governs the parts of the house that matter most in a wildfire: roofing, siding, exterior walls, windows, decks, soffits, and vents. These are not abstract regulations. They are a checklist of exactly where a home is vulnerable.
This is a whole-region risk, not a Napa problem
People assume wildfire is something that happens "up in wine country." It isn't. The Oakland Hills Fire of 1991 burned 1,520 acres, destroyed 3,354 homes, and killed 25 people — in the heart of the East Bay. Marin County carries multiple Very High Fire Hazard Severity Zones today, including Mill Valley and Tiburon. Even San Francisco has Wildland-Urban Interface zones — Twin Peaks, Bernal Heights, Glen Canyon — where the city meets open hillside and embers can travel.
And then there's Napa Valley, which has lived this repeatedly. The 2017 Atlas, Tubbs, and Nuns fires. The 2020 LNU Complex, which burned across roughly one-third of Napa County. The 2020 Glass Fire, which destroyed 1,555 structures and stands as the most destructive fire in Napa Valley history. If you build or own here, fire isn't a possibility you plan around once — it's a recurring fact of the landscape.
The point is simple: from a remodel in San Francisco to an estate in the hills above Calistoga, fire-resistant construction is now a Northern California standard, not a regional specialty.
What's actually required — and what you should do
Here's the part homeowners ask us about most. Under Chapter 7A and the standards taking hold in 2026, a properly fire-hardened home addresses each vulnerable surface deliberately. The essentials we build to:
- A Class A roof assembly — tested to ASTM E108 / UL 790. The roof is the single largest ember-catcher on the house, and a Class A assembly is the floor, not the ceiling, of what's required.
- Ember-resistant vents — fine mesh and baffled designs that keep wind-driven embers out of attics and crawlspaces, where most homes quietly ignite from the inside.
- Non-combustible or ignition-resistant siding and decks — fiber cement, stucco, mineral systems, and rated decking instead of materials that feed a fire.
- Tempered or multi-pane glazing — windows that don't shatter from radiant heat and let flames into the structure.
- Defensible space — Zone 0 (0–5 ft) kept clear and non-combustible, Zone 1 (5–30 ft) lean and managed, and Zone 2 (30–100 ft) thinned to slow an approaching fire.
Defensible space deserves emphasis. Zone 0 — that first five feet against the house — is where a single wood mulch bed or stack of firewood can undo every dollar you spent on the structure. The building and the landscape have to be designed as one system.
The real threat isn't the wall of flame
This is the thing most people get wrong, and it changes how you should think about the whole project.
Most homes don't burn because the fire front reaches them. They burn because wind-driven embers — blown a mile or more ahead of the fire — land in a vent, on a deck, in a gutter, or against a wood fence, and find one weak point. Harden against embers and you've defended against the way the vast majority of homes are actually lost.
Once you understand that, the priorities reorder themselves. The dramatic stuff — the flames you see on the news — is rarely what takes the house. It's the small, unglamorous details: the vent that wasn't ember-rated, the gap under the deck, the combustible trim at a roofline. Get those right and you've done most of the work.
Why an experienced builder matters now
Fire-resistant construction is not a product you bolt on. It's a discipline that lives in the detailing — the transitions, the assemblies, the dozens of small decisions a crew makes that no inspector will ever see once the walls are closed. A builder who has only just started meeting these codes because 2026 forced them to is learning on your house.
I'm not. I built to these standards for years before they were required, on the same hillsides the new maps now cover, because it was obviously the right way to build in this region. That experience is the difference between a home that technically passes plan check and a home that's genuinely ready for the next fire season.
If you're building, remodeling, or simply trying to understand where your property now stands on the new maps, that's exactly the conversation I'm glad to have. The codes have finally caught up to how Northern California homes should have been built all along — and the homeowners who move early are the ones who sleep well in October.
Work With Robin
Ready to talk through a fire-resistant build or remodel?
Robin will walk your site, read your property against the new hazard maps, and lay out what's required — no pressure, no obligation.