Home Hardening for Wildfire in Napa, Sonoma and Marin

Home hardening means upgrading the parts of a house that wildfire embers, flames and radiant heat attack first: the roof, vents, gutters, eaves, windows, siding, decks and the first five feet around the walls. In Napa, Sonoma and Marin it also matters for insurance, because California requires insurers to give discounts for listed mitigation steps. Marin homeowners can also draw on county-wide programs funded by Measure C.

This post sets out the upgrades in a sensible order, what the state’s insurance framework rewards, where the new Zone 0 rules stand as of October 2026, what local help exists, and how to document the work when you sell. It doesn’t quote costs, which vary by house and contractor.

Why hardening matters

CAL FIRE’s guidance names three ways wildfire reaches a house: direct flames, radiant heat and flying embers. It warns that embers can be particularly destructive and can ignite homes up to a mile from the fire. That is why most hardening work is about closing the gaps and removing the fuel that embers find: vents, gutters full of leaves, wood mulch against the wall, a stack of firewood under the deck.

Hardening and defensible space work together. Hardening is the building; defensible space is the land around it. Neither replaces the other, and insurers and the state ask about both.

The upgrades, in a practical order

Start with the cheapest fixes that close the biggest openings, then plan the larger projects. The specifications below are from CAL FIRE’s Ready for Wildfire guidance unless noted.

CAL FIRE calls the roof the most vulnerable part of a home, so a wood shake roof belongs at the top of the list even though it is the most expensive item. Ember-resistant vents can reduce attic and underfloor airflow, so check ventilation requirements with your building official and use a licensed contractor. Diamond may refer you to partners we work with; you’re free to choose any provider.

What earns an insurance discount

Safer from Wildfires is the California Department of Insurance’s list of mitigation steps that insurers must recognize in their rates. According to the Department, each item on the list earns a discount, and completing more items can add to the savings. At the property level, the list is:

• a Class A fire-rated roof (most roofs qualify; wood shake shingles don’t);
• a five-foot ember-resistant zone, including replacing wood fencing attached to the house with metal;
• ember- and fire-resistant vents with noncombustible metal mesh;
• six inches of noncombustible material at the bottom of exterior walls, measured from the ground and from any attached horizontal surface such as a deck;
• enclosed eaves;
• multi-pane windows or shutters;
• cleared vegetation and debris under decks;
• combustible outbuildings, such as sheds, gazebos and ADUs, at least 30 feet from the home;
• compliance with state and local defensible space rules.

At the community level, Firewise USA sites and the Board of Forestry’s Fire Risk Reduction Communities also count. When the Department announced the regulation on October 17, 2022, it said insurers must also give consumers their property’s wildfire risk score and a right to appeal it.

How much you save depends on your insurer’s approved rates, and a discount is not a guarantee of coverage. If you are on the California FAIR Plan, ask about its own hardening discounts. Our guides to the FAIR Plan and insuring a high-value home go further.

IBHS Wildfire Prepared Home

Wildfire Prepared Home is a voluntary mitigation and assessment program run by the Insurance Institute for Business & Home Safety (IBHS). It is offered in California and 13 other western and southern states, and its site compares two levels, Essential and Enhanced. The process has three steps:

1. The homeowner completes the work on the program’s preparation checklist, which puts heavy weight on the five feet around the house.
2. The homeowner pays a nonrefundable application fee and submits eligibility photos.
3. A third-party evaluator inspects the work in person. If anything is left, the owner has 60 days to finish it and send photos.

A designation is a documented, third-party record of the work, which is useful both with an insurer and with a buyer. Ask your insurer how it treats the designation before you apply.

Zone 0 and defensible space in October 2026

Zone 0 is the ember-resistant zone within five feet of the house. As of October 2026 the rules are adopted but not in effect. The Board of Forestry’s Zone 0 page posts an August 19, 2026 decision memo, and when we checked it on October 24, 2026 it said staff were still working with the Office of Administrative Law on a final review and would update the page once the Secretary of State publishes the final regulation. Our post on Zone 0 rules and home sales tracks each step.

Even before Zone 0 takes effect, the first five feet are on the insurance list above, and existing defensible space law still applies. In High and Very High Fire Hazard Severity Zones, many sales need a defensible space inspection; see our guide to AB 38 inspections, and check your parcel’s zone with our guide to North Bay fire hazard severity zones.

Building codes for new work

For years, California’s wildfire building standards sat in Chapter 7A of the Building Code. The International Code Council reports that the state adopted a stand-alone California Wildland-Urban Interface Code, Title 24 Part 7, on February 26, 2025, and that Part 7 replaces Chapter 7A.

The Building Standards Commission lists the 2025 California Building Standards Code, which includes Part 7, as effective January 1, 2026. A home permitted in a mapped zone before 2026 may have been reviewed under Chapter 7A; permits issued from 2026 on fall under Part 7.

Which standards govern a particular project is up to your local building department, and some agencies adopt local amendments. If you are replacing a roof, siding or windows, ask at the permit counter which wildfire standards apply, so the work counts both for the code and for your insurer.

Local help in Marin, Sonoma and Napa

Marin County

The Marin Wildfire Prevention Authority coordinates a county-wide wildfire program funded by Measure C, a special tax on Marin’s 2020 primary ballot that passed with 70.8% of the vote, according to the Authority and a 2021 Western City magazine article. Its programs include defensible space and home hardening evaluations, grant programs, including a home hardening matching grant, and chipper days run with FIRESafe MARIN. The Authority’s September 2026 executive officer’s report also mentions new wildfire resilience loans for home hardening and Zone 0 work.

The Authority’s resident grant page, written for the 2024-25 program year, describes grants of up to $2,500 per parcel with no resident match, a $15,000 lifetime cap across its programs, and eligibility tied to a hazard identified in the owner’s Wildfire Risk Report from an evaluation. Eligible work includes:

• metal gutters and gutter guards;
• fire-resistant vents, with screening of 1/8 inch or finer;
• a noncombustible gate or fence section attached to the house;
• clearing hazardous vegetation in the first 30 feet, where the report lists it.

The page said applications stay open until funds run out. Its dates are from 2024, so confirm the current terms with the Authority before you budget around a grant.

Sonoma and Napa counties

In Sonoma County, Permit Sonoma’s Wildfire Adapted program, branded SoCo Adapts, offers free home hardening and defensible space assessments in its project area. They are guidance, not code inspections. When the Board of Supervisors approved the assessment contract on September 13, 2022, the county described the program as part of $2.6 million in FEMA Hazard Mitigation Grant Program funding. The Sonoma County Fire District’s SoCo Adapts page says owners in the project area may be eligible in 2026 for a rebate of about $10,000 per parcel for priority wildfire resilience work, and that owners who complete a full home hardening assessment can apply it to hardening projects. The page gives no opening date, so check with the program at (707) 565-8575 before planning around it.

In Napa County, United Policyholders’ Napa resource page (last updated November 2024) lists a Napa Firewise defensible space cost-share program reimbursing 50% of qualifying new projects up to $3,500 per property, defensible space consulting inspections from the Napa County Fire Marshal’s Office, and a free chipper program for residents in designated fire hazard zones. We didn’t find a county-run grant for structural hardening in Napa; ask the Napa Communities Firewise Foundation what is currently funded.

Selling or buying a hardened home

For sellers, documented hardening work answers a buyer’s first insurance questions. California also requires a specific disclosure for many older homes in high-hazard areas: under Civil Code section 1102.6f, the seller of a home built before January 1, 2010, in a High or Very High Fire Hazard Severity Zone must give the buyer a notice that the home was built before the wildland-urban interface building codes and may need improvements. The seller must also disclose features the seller is aware of that make the home vulnerable, such as open vents, an untreated wood shake roof, single-pane windows or uncovered gutters. Since July 1, 2025, the seller must also give a list of the state’s low-cost retrofits and say which were completed during the seller’s ownership.

• Keep the paperwork. Permits, contractor invoices, product specifications for vents and windows, photos and any IBHS designation.
• Put it in the property file. Share it with buyers early, alongside the defensible space inspection and any insurance quotes; our guide to pre-listing inspections covers what else goes in.
• Describe it accurately. State what was done and when, not what it achieves. A disclosure that overstates fire resistance invites a dispute later; see California seller disclosures.

For buyers, the hardening list doubles as a due diligence checklist. Ask for the seller’s records, check the roof and vents during the inspection, and get insurance quotes before you remove contingencies; our guide to homeowners insurance during escrow explains the timing. If you plan upgrades after closing, price them before you settle on an offer. Hardening is one of several improvements worth weighing; see our post on renovations that pay back at resale.

This is general information, not legal or insurance advice. For coverage questions, talk to a licensed California insurance broker, and ask a California real estate attorney about disclosure duties on your sale.

Questions people ask

What is home hardening?

Upgrading a home’s roof, vents, gutters, eaves, windows, siding, decks and the area right around the walls so that embers, flames and radiant heat are less likely to ignite it.

Does home hardening lower insurance premiums in California?

It can. The Department of Insurance says every action on its Safer from Wildfires list qualifies for a discount, with more savings for doing more. The size of the discount depends on your insurer’s approved rates.

What are the most important home hardening upgrades?

CAL FIRE calls the roof the most vulnerable part of a home. Vents with fine metal mesh, clean gutters and a clear five-foot zone around the house are smaller jobs that close common ember entry points.

Are there home hardening grants in Marin County?

The Marin Wildfire Prevention Authority lists home hardening and defensible space grant programs, including a matching grant, funded by Measure C. Check its resident grants page for current terms and availability.

Is Zone 0 required now?

Not as of October 2026. The Board of Forestry adopted the rules in August 2026, but on October 24, 2026 its page said they were still in final review with the Office of Administrative Law. Existing defensible space law still applies.

What is a Wildfire Prepared Home?

A voluntary designation from the Insurance Institute for Business & Home Safety, issued after a third-party evaluator confirms the home meets the program’s requirements. It is available in California.

Do I have to disclose home hardening when I sell?

For a home built before 2010 in a High or Very High Fire Hazard Severity Zone, Civil Code 1102.6f requires a home hardening notice, disclosure of known vulnerable features and, since July 1, 2025, a list of low-cost retrofits showing which were done. Other disclosure rules apply to every sale.

If you are getting a home ready to sell in fire country, we can help you decide which upgrades and records are worth doing first. See how we prepare a home for sale, or browse our luxury and estate property services.

Sources & notes

• CAL FIRE Ready for Wildfire: Hardening your home
• California Department of Insurance: Safer from Wildfires
• California Department of Insurance: Safer from Wildfires regulation announcement (Oct. 17, 2022)
• Insurance Institute for Business & Home Safety: Wildfire Prepared Home
• Marin Wildfire Prevention Authority: home page and programs
• Marin Wildfire Prevention Authority: Resident grant program
• Western City (League of California Cities): How Marin County is changing the wildfire prevention paradigm (Sept. 1, 2021)
• Sonoma County Fire District: SoCo Adapts free home hardening and defensible space assessments
• Permit Sonoma: Board approves contract for wildfire structural hardening assessments (Sept. 13, 2022)
• United Policyholders: Wildfire resources for Napa County
• Justia: California Civil Code section 1102.6f (home hardening disclosure)
• California Building Standards Commission: California Building Standards Codes
• International Code Council: California adopts 2024 International Wildland-Urban Interface Code
• California Board of Forestry and Fire Protection: Defensible space Zones 0, 1 and 2

Last reviewed October 2026 by Matthew Martinez.