Start with your parcel's fire hazard zone
Whether wildfire construction rules apply to your rebuild depends first on how your lot is mapped. On March 24, 2025, the State Fire Marshal issued updated Fire Hazard Severity Zone maps for the local responsibility areas of Los Angeles County. Earlier local maps showed only Very High zones; the 2025 maps classify land as Moderate, High, or Very High, and in July 2025 the County Fire District asked the Board of Supervisors to bring those maps into the County Fire Code.
Altadena parcels do not all share one designation. Ratings can change from one block to the next, and some lots that burned sit in a lower zone or outside a mapped zone entirely. We look up the designation on the County's fire hazard map during the first site visit, because it changes the roof, siding, window, and landscape plan before any pricing is done.
Which wildfire code applies in 2026
For years, California's wildfire construction rules lived in Chapter 7A of the Building Code and Section R337 of the Residential Code. Starting January 1, 2026, those provisions moved into a standalone document, the 2025 California Wildland-Urban Interface Code. The State Fire Marshal also adopted emergency amendments, effective the same day, making clear that the standards apply in both Very High and High zones in local responsibility areas.
Los Angeles County adopted the 2025 state codes with its own amendments as the 2026 County Building Code, effective January 1, 2026. The County's version applies the wildfire construction chapter to new buildings and to additions, alterations, and repairs within any Fire Hazard Severity Zone or wildland-urban interface area, and it bars wood shingle and wood shake roofs in any of those zones regardless of fire rating. The code edition that governs your project generally follows the date your permit application was filed, so we confirm that with plan check at the start.
Roof, gutters, and attic vents
Embers that land on a roof or slip into an attic are a leading way homes ignite, so the roof gets the most attention. In a mapped zone the County's construction notes call for a Class A roof assembly. Profiles that leave a gap under the covering, such as some tile, need that space fire stopped or a 72 pound mineral surfaced cap sheet over the deck. Valley flashing must be galvanized sheet metal of at least 26 gauge over a 36 inch wide cap sheet, and gutters and downspouts must be noncombustible with a way to keep leaves from collecting.
Attic, eave, and underfloor vents must resist ember and flame intrusion, either through a vent listed to the ASTM E2886 test or through noncombustible, corrosion resistant mesh with openings between 1/16 and 1/8 inch. Vents in the underside of eaves are limited to specific approved conditions. We coordinate vent locations with the framing and the energy design early, since changing a vent strategy after the roof is framed costs time.
Walls, eaves, windows, and doors
Exterior walls in a mapped zone need a qualifying covering or assembly. Options in the County notes include noncombustible siding such as stucco or fiber cement, ignition resistant materials, fire retardant treated wood labeled for exterior use, or an assembly with 5/8 inch Type X gypsum sheathing behind the cladding. Paints and coatings do not count as protection. At least 6 inches of metal flashing or noncombustible material is required where walls meet the ground, decks, and roofs, which is exactly where wind blown debris piles up.
Eaves, porch ceilings, and floor projections have their own lists of approved undersides. Exterior glazing, including skylights and glass doors, must be multi pane with at least one tempered pane, glass block, rated for at least 20 minutes, or tested to the State Fire Marshal standard. Exterior doors must be noncombustible, ignition resistant, solid core wood meeting minimum thicknesses, or rated. Large windows are possible in a hardened home; they simply need the right glass specification from the first window order.
Decks, patio covers, and the ground around the house
Deck walking surfaces must use ignition resistant, noncombustible, or fire retardant treated material, or a product that passes the required State Fire Marshal or ASTM tests. Trellises, patio covers, carports, and similar structures with any part within 50 feet of the house must be noncombustible, ignition resistant, or heavy timber.
The land around the home is part of the plan too. According to the County, a rebuild inside a Fire Hazard Severity Zone requires a fuel modification plan reviewed by the Fire Department, and Very High zone parcels are part of the County Fire defensible space inspection program. In August 2026 the State Board of Forestry approved rules for Zone 0, the first five feet around a structure, for local Very High zones and state responsibility areas; final state filing was still pending when we wrote this, so we check its status for your project and keep that perimeter free of combustible materials in our site plans.
Sprinklers, water, and fire access
Every rebuilt home needs interior fire sprinklers under current code, and the County Fire Department reviews plans for the rebuilding of destroyed buildings. Its rebuild guidance also covers fire flow from nearby hydrants and access for fire apparatus, with a higher flow requirement for homes inside a Fire Hazard Severity Zone. On streets where the water system or the driveway cannot meet those standards, the Fire Marshal can consider appeals, so we gather the hydrant flow form and site measurements before plans are final.
Hardening a home outside a mapped zone
Much of what burned in the Eaton fire sat outside the highest mapped zones, and state maps model fire moving through wildland vegetation rather than from house to house. Los Angeles County encourages owners outside a Fire Hazard Severity Zone to use the wildfire construction standards voluntarily. If your lot is not mapped, we can price the hardening measures as separate line items, such as a Class A roof, ember resistant vents, tempered glazing, and a noncombustible strip at the base of the walls, so you can decide which ones to include with real numbers in front of you.