On February 26, 2025, California became the first state in the country to adopt the 2024 International Wildland-Urban Interface Code as the basis for its own WUI code, per the International Code Council. The adoption created a new Title 24 Part 7 — the 2025 California Wildland-Urban Interface Code — and consolidated requirements that had previously lived scattered across Chapter 7A of the Building Code and adjacent sections. The effective date is January 1, 2026. For any Palisades or Eaton rebuild reaching permit in the first half of 2026, Part 7 is the framework the plans must answer to.
The California Building Standards Commission has been explicit about the relocation: Chapter 7A's material and assembly requirements have been moved into the unified Part 7 WUI Code. The substance carries forward — Class A roof coverings, ignition-resistant exterior walls, and ember-resistant vents tested to ASTM E2886 remain the regulatory core, now alongside the 2024 IWUIC's cleaner administration of defensible-space and access provisions. And the underlying Chapter 7A text remains the reference the plan-checker will pull on.
The three pillars — roof, walls, vents
Title 24 Part 7's technical core is narrower than the code volume suggests. A Class A roof covering. Non-combustible exterior walls, or walls of ignition-resistant assembly. Ember-resistant vents on every opening that penetrates the building envelope. Those three items do most of the work, and it is on those three items that the Mediterranean villa typology arrives already compliant.
The roof is the clearest case. NIST Technical Note 1794, Manzello's 2013 experimental study, exposed concrete and terracotta tile assemblies to wind-driven firebrand showers at 9 m/s wind and 10 g/m²·s firebrand generation. Flat interlocking terracotta tile performed best of the assemblies tested — its interlocking geometry trapped firebrands in the joints before they could reach underlayment, preventing the sub-tile ignitions that destroy otherwise-intact Class A roofs. Terracotta is not merely Class A on the certificate; under the test conditions that actually reproduce an urban wildfire, it is the tile that performs.
The wall is the second pillar. The 2025 FSRI/UL study by Gorham, Willi and Horn quantified what the code has long implied: noncombustible fiber cement required a closer 6-foot proximity to an ignition source to ignite, while combustible alternatives — including EIFS, which the study showed melts and pools to burn at the wall base — ignited at greater distances. Stucco over concrete or masonry moves that envelope-to-envelope proximity line even further out. The vent is the third pillar, and ASTM E2886-compliant ember-resistant vents are now the code floor — not a discretionary upgrade.
Zone 0 — the regulatory line that moved, then paused
California's statutory basis for the 0–5 foot non-combustible ember-resistant zone is AB 3074 (2020). In December 2025, per Wildfire Los Angeles, the State Board of Forestry paused Zone 0 rulemaking past the December 31, 2025 deadline set by Executive Order N-18-25 — deferring regulatory finalization to March 2026. The statutory requirement did not go away; the regulation to operationalize it was simply pushed. For a 2026 custom build, the correct posture is to design to AB 3074's intent at day one, regardless of when the final rule lands.
The IBHS Wildfire Prepared Home standard, updated June 17, 2025, does not wait for the Board of Forestry. It already treats the 0–5 ft non-combustible zone as essential for halting ember and flame ignition at the foundation line, and it is the non-negotiable prerequisite for IBHS certification. A Mediterranean villa oriented around a paved inner courtyard and a stone or gravel perimeter delivers Zone 0 by geometry — the defensible perimeter is a design move, not an appended strip.
What the IBHS Palisades/Eaton field data actually showed
In December 2025, IBHS published its field study of 250+ properties in the Palisades and Eaton fires. The headline number: homes with four hardening features — Class A roof, non-combustible siding, double-pane windows, and enclosed eaves — survived at a 54 percent rate, versus 36 percent for homes that had adopted only one measure. That is an 18-point survival spread for what is, in 2026 code terms, an already-required specification package. The corollary is sharper. Where Zone 0 fuel coverage exceeded 25 percent, post-fire structure-loss risk approached 90 percent regardless of what the structure itself was made of. The non-combustible perimeter is not an accessory to the envelope; it is the envelope's first line.
The Mediterranean villa as ready-made compliant typology
Read Part 7 through its three pillars and the IBHS field data together, and the building the code is asking for is recognizable. A terracotta roof on a Class A assembly. Non-combustible walls — stucco over reinforced concrete or masonry — meeting the FSRI proximity thresholds by material, not by separation distance. ASTM E2886 ember-resistant vents. A 5-foot non-combustible Zone 0 delivered by a paved courtyard or stone perimeter. That is not a retrofit specification; that is the typology Palladio drew for Villa La Rotonda in 1566 and that has shaped the Italian villa since antiquity.
For the Los Angeles rebuild brief in 2026, this matters less as a piece of architectural theory and more as a permit-path outcome. A plan set that begins with the Mediterranean villa typology reaches Title 24 Part 7 compliance on the first pass, not on the third review. The code language and the typology converge — and the villa that was built for sun, stone, and mistral wind happens to be the building the California WUI Code is now asking for.