10 min read · Fire-Resistant
The first five feet around a California home are becoming regulated space. AB 3074, signed in 2020, ordered the creation of an 'ember-resistant zone' — Zone 0 — in the area within five feet of structures in the state's highest-hazard areas, and the Board of Forestry and Fire Protection has spent the years since writing the rules that define it. As of this writing in mid-2026, those rules are still a draft — the statutory deadline came and went, and an updated draft went to public workshop in April 2026 — but the direction is unambiguous, and the physics behind it don't wait for rulemaking. This guide covers what Zone 0 is, exactly where the regulation stands (date-stamped, because it's moving), and the part most Zone 0 coverage skips: the wall itself, where your siding meets the fuel the rule is trying to remove.
What Zone 0 is and where it came from
Zone 0 is the ember-resistant zone covering the first **0–5 feet** out from a structure — the strip where wind-driven embers land, lodge, and start the ignitions that burn homes down long before any flame front arrives. It was created by AB 3074 (2020), which amended California's defensible-space statute (Public Resources Code §4291) to add a third, most-intense tier to the familiar 30-foot and 100-foot defensible-space framework, and directed the Board of Forestry and Fire Protection to write the regulations defining what the zone requires. The target population is the state's highest-exposure homes: parcels in the State Responsibility Area and in Very High Fire Hazard Severity Zones within local responsibility areas. The science behind the five-foot figure is the same research base behind the IBHS and CAL FIRE hardening programs — post-fire investigation consistently shows embers igniting mulch, vegetation, fences, and stored combustibles against the wall, then the wall itself. Zone 0 is the regulatory version of a conclusion fire researchers reached years ago: the material touching your house is part of your house.
Where the rules stand — a date-stamped status check
Here is the honest status, stamped **as of mid-2026**, because this is a moving regulation and undated claims about it age badly. AB 3074 contemplated regulations by January 1, 2023; that date passed. Governor Newsom's Executive Order N-18-25 then directed the Board of Forestry to complete Zone 0 rulemaking by December 31, 2025; that deadline also passed without adoption. The Board's Zone 0 committee resumed work in 2026 and released an **updated draft on April 17, 2026**, taken to public workshop on April 23, 2026 — a draft that, notably, emphasizes education and phased outreach over immediate penalties, responding to affordability and feasibility comments gathered through 2025. As of this writing the regulation **remains a draft: it has not been adopted, and no compliance clock is running yet**. The statute itself fixes the sequencing whenever adoption comes: Zone 0 applies to **new structures first** (upon the regulations taking effect) and to **existing structures one year after** the new-structure requirements commence, and the draft materials layer a multi-year phase-in over that — with the earliest phase for existing homes focused on removing loose combustibles (mulch, firewood, dead vegetation) from the five-foot strip. Check the Board of Forestry's defensible-space page for the current text before making decisions on dates; anything more specific than the above is speculation, and we won't print speculation as compliance advice.
What the draft expects in the first five feet
The draft rules and the Board's published FAQ sketch a consistent picture of what an ember-resistant zone means in practice, even while details are finalized. Out: **combustible mulch** (bark, wood chips) against the structure; **combustible vegetation** in the strip, including dead material and most live plants; **stored combustibles** — firewood stacks, lumber, furniture cushions, trash and recycling bins — parked against the wall; and **combustible fencing and gates** attached to the structure, which act as fuses that carry fire straight to the siding. In: **noncombustible hardscape** — gravel, pavers, concrete, stone — bare soil, and noncombustible fencing sections where a fence must meet the wall. If that list sounds familiar, it should: it's substantively the same 0–5 ft standard the IBHS Wildfire Prepared Home program already requires at both tiers, and the same guidance CAL FIRE has published for years on readyforwildfire.org. The regulation's job is to turn best practice into a baseline. The open questions in the rulemaking are mostly about edges — mature trees, phased timelines, enforcement posture — not about whether bark mulch belongs against a wall in a Very High zone. It doesn't, and every serious source has said so for years.
The siding angle: where the wall meets the fuel
Most Zone 0 coverage treats it as a landscaping rule. We'd point you at the vertical surface bounding the zone: the wall. Zone 0 exists because embers ignite what's against the house and the fire climbs — so the zone and the cladding are two halves of one system. Three wall details do most of the work. First, **cladding-to-grade clearance**: siding that runs down into soil or mulch wicks moisture in normal years and meets ground fire directly in bad ones; manufacturer specs require ground clearance for exactly this reason, and our cladding-to-grade guide covers the detail in depth. Second, the **base of wall**: the bottom 6+ inches of the wall is the surface radiant heat and surface flame reach first, which is why both the IBHS standard and California's Safer from Wildfires framework single out a noncombustible wall base — exposed concrete, fiber cement, stone, or metal flashing — as its own line item. Third, **attachments**: a combustible fence or gate tied into the wall defeats both the zone and the cladding, which is why the drafts and the IBHS checklist require noncombustible transitions where fences meet structures. A wall that is noncombustible from grade up, with a compliant zone in front of it, removes the ignition sequence Zone 0 targets. Neither half makes a home fireproof — nothing does — but together they take away the most common way homes ignite.
How a re-side coordinates with Zone 0 compliance
If you're re-siding a home in a Very High severity zone or the SRA in the next few years, the smart move is to fold Zone 0 into the project rather than retrofitting around finished work. In practice that means: setting the new cladding's bottom edge at proper clearance over what the zone will become (gravel or hardscape, not the lawn or bark that's there today); building the **noncombustible base-of-wall detail** into the scope now, since it's cheap during a re-side and awkward afterward; specifying fiber cement or another noncombustible cladding so the wall side of the equation is settled — our fire-resistant siding guide compares the options; replacing the first section of any attached fence with a noncombustible panel while the wall is open; and detailing vents, gutters, and downspout terminations so the finished assembly doesn't collect ember-catching debris at the wall base. Where the WUI building code already applies to your parcel, much of this is required anyway — our siding code and fire-zone reference maps those triggers — and the same scope positions you for the IBHS designation if you want a named standard out of the work. Honest boundary, as always: the landscaping, the trees, and most of the zone itself are outside a siding contract. We handle the wall and its immediate details, and we'll tell you plainly which Zone 0 items a re-side does and doesn't cover.
Why acting before adoption still makes sense
It would be easy to read 'still a draft' as 'wait and see,' so here's the honest counterargument. The physics are not in draft: embers ignite the five-foot strip today, whether or not a regulation says so, and CAL FIRE and the UC ANR Fire Network have recommended an ember-resistant zone and noncombustible wall materials for years on the strength of post-fire evidence alone. The insurance system isn't waiting either: California's Safer from Wildfires framework already recognizes the 5-foot ember-resistant zone and the noncombustible wall base as discount-eligible mitigation — carrier-dependent, never guaranteed, but recognized now — and if you've been non-renewed, documented Zone 0-style work belongs in the requote file our non-renewal playbook describes. And the direction of the rule is settled even where its dates aren't: no plausible final text puts bark mulch back against the wall. Doing the work now means doing it on your schedule, folded into projects you're doing anyway, instead of on a compliance deadline alongside every other homeowner in your severity zone. Just date-check anything you read about Zone 0 — including this page — against the Board of Forestry's current materials before treating it as final.
Zone 0 draft requirements vs. what a re-side project can address (as of mid-2026 draft materials)
| Zone 0 item (draft) | In a siding contract? | How a re-side addresses it |
|---|---|---|
| Combustible mulch/vegetation in 0–5 ft | No — landscaping scope | Coordinate finished grade and cladding clearance over future hardscape |
| Noncombustible base of wall | Yes | Fiber cement, metal flashing, or exposed concrete at the bottom 6+ inches |
| Cladding-to-grade clearance | Yes | Set bottom edge per manufacturer spec above soil/hardscape |
| Combustible fence/gate attached to wall | Partially | Noncombustible transition panel where fence meets structure |
| Stored combustibles against wall | No — homeowner maintenance | N/A — but a clean wall base makes violations obvious |
| Ember-resistant vents at wall | Yes | Upgrade vents and seal ember entry points during the re-side |
Key takeaways
- Zone 0 is the 0–5 ft ember-resistant zone created by AB 3074 (2020) for homes in the State Responsibility Area and Very High Fire Hazard Severity Zones — the most intense tier of California's defensible-space framework.
- As of mid-2026 the regulation is still a DRAFT: the December 31, 2025 deadline passed without adoption, an updated draft went to workshop in April 2026, and no compliance clock is running — verify current status with the Board of Forestry before acting on dates.
- The statute sequences compliance: new structures first when regulations take effect, existing structures one year later, with draft materials adding a multi-year phase-in that starts with removing loose combustibles like mulch and firewood.
- The wall is half the system: cladding-to-grade clearance, a noncombustible base of wall, and noncombustible fence transitions are where a re-side directly serves Zone 0 — and they're far cheaper to build in during the project than to retrofit.
- The five-foot strip's requirements already exist in practice — IBHS requires it, Safer from Wildfires recognizes it for carrier discounts — so hardening now runs on your schedule instead of a future compliance deadline; and noncombustible never means fireproof.
FAQ
Quick Answers
Not yet, as of mid-2026. AB 3074 created the requirement in statute, but it only takes effect once the Board of Forestry and Fire Protection adopts implementing regulations — and those are still in draft, with an updated version released in April 2026 after the December 31, 2025 deadline passed without adoption. When adoption comes, the statute applies the rules to new structures first and to existing structures one year after that, and the draft materials describe a phased, education-first rollout beyond that. Check the Board of Forestry's defensible-space page for the current status before relying on any date, including anything on this page.
Based on the draft rules and the Board's published materials: combustible mulch such as bark and wood chips, combustible vegetation including dead material and most plants, stored combustibles like firewood and lumber against the wall, and combustible fencing or gates attached to the structure. Noncombustible hardscape — gravel, pavers, concrete, stone — and bare soil are the compliant surfaces. Details are still being finalized (mature trees and phase-in timing have been the contested edges), but the core list has been consistent across drafts and matches what IBHS and CAL FIRE already recommend.
No — Zone 0 regulates the ground and attachments in the five-foot strip, not the wall covering itself. But the two work as one system: the zone removes fuel at the base of the wall, and noncombustible cladding removes the wall as the next link in the ignition chain. If your parcel is in a Very High severity zone, the WUI building code may separately govern your siding materials when you re-side, and a re-side is the cheapest moment to add the noncombustible base-of-wall and fence-transition details that Zone 0 thinking calls for. We'll tell you which applies to your address rather than treating every home as the worst case.
We'd argue no, for three honest reasons. The ember physics the rule addresses operate today regardless of rulemaking status — CAL FIRE has recommended an ember-resistant zone for years. California's Safer from Wildfires insurance framework already recognizes the 5-foot zone and noncombustible wall base as discount-eligible mitigation (amounts are carrier-dependent and never guaranteed). And no realistic final rule reverses direction and permits combustible mulch against walls in Very High zones. Waiting mainly means doing the same work later, on a deadline, in a busier market. The one thing worth waiting on is anything that depends on exact compliance dates — verify those against the Board of Forestry's current text.
Sources
Authoritative references
- California Board of Forestry & Fire Protection — Defensible Space Zones 0, 1, and 2 (Zone 0 rulemaking)
- Board of Forestry — Frequently Asked Questions about Zone 0 (September 17, 2025)
- AB 3074 (2020) — bill text creating the ember-resistant zone (amending PRC §4291)
- CAL FIRE Ready for Wildfire — defensible space & the 0–5 ft ember-resistant zone
- UC ANR Fire Network — Siding (vinyl combustibility & sheathing dependence; noncombustible options)
External links to government, code, and manufacturer sources. Sierra Siding is not affiliated with these organizations; references are provided for verification.