Zero Zero: The Regulations Being Defined Right Now

Within California’s high fire hazard areas, Zone Zero is defined as the first zero-to-five feet extending away from any structure. In the coming months, the California Board of Forestry will decide what you are allowed to have in this space nearest your home. If you live in Montecito or Santa Barbara between the Santa Ynez Mountains and the sea, odds are this will affect you directly. 

In 2020, California passed legislation to create an “ember-resistant” zone in this zero-to-five feet range. Its purpose is to decrease the risk of structure ignition due to wind-driven embers landing nearby. Until now, however, this legislation has not been put into effect. 

Following January’s Palisades and Eaton fires, California Governor Gavin Newsom signed an executive order mandating the Board of Forestry define these rules for Zone Zero by December 31, 2025. Aspects of the Zone Zero plan are, for all intents and purposes, unanimously agreed upon: the removal of outbuildings as well as wooden gates and fences, and the importance of clearing leaf litter. However, the most recent draft of Zone Zero from August 18 calls for removal of all “grass, ornamental or native plants, shrubs, fallen leaves and tree needles, weeds…” Trees are only allowed if they stand five feet taller than your house and have their branches maintained five feet away from it. Effectively, the only plants you will be allowed to have within five feet of your home are potted plants less than 18 inches tall – and even this allowance is provided you do not place them in front of your windows, and you do bring them inside during a fire event.

If the rules are implemented in their current form, it would mean the clearing of thousands of trees, shrubs, and other plants from our communities. And yet, there is ambiguous scientific evidence at best to suggest that this would actually reduce the risk of a home’s ignition during a fire event. In fact, it is possible that the plants closest to your home may stop embers and flames from reaching it. 

What we know for sure is that home hardening reduces the chances that your home catches on fire. In the cases of the wind-driven fires California has experienced in recent years, homes are ignited primarily in two ways: from structure to structure and from flying embers. Wind carries embers sometimes miles from a blaze to beneath wooden decks or into debris-filled roof gutters or directly into homes through vents. Installing fine mesh screens over vents and double-pane windows greatly reduce the chances a structure will be ignited by embers.

We also know that consistently maintaining one’s yard by removing leaf litter and clearing dead vegetation as well as having defensible space near your home for firefighters to maneuver are both correlated with decreased risk of home loss. There are parts of Zone Zero that should absolutely go into effect. However, to mandate from what we know at this time essentially five feet of empty space around homes seems like a stretch.

What Do the Studies, Experts, and Meetings Say

A recent study using simulation found that home hardening alone could increase the chances of home survival to 25% (without firefighter intervention). Home hardening combined with a clear Zone Zero would jump that up to a 40%. Yet, as it stands, California will be mandating Zone Zero regulations and not home hardening. The study does not consider the effects of a clear zero-to-five feet range alone (without home hardening). Furthermore, this is one study and the first of its kind. There is nearly zero scientific literature on the subject of a clear versus planted Zone Zero. 

Another preliminary study yielded an opposite result: homes with high moisture content trees within 30 feet and at least 20% of the bare ground covered within Zone Zero were more likely to survive. 

“From the plant flammability side of things, removing all the vegetation isn’t well founded in science,” said University of California Santa Barbara Professor Max Moritz. He explained that while plants like juniper, Italian cypress, and palm trees have been noted to ignite quickly, potentially assisting in the spread of fire, others – like high-moisture, drought resistant natives – may have a protective effect. Very few studies have considered the role of vegetation on ignition. “Home hardening is by far the most effective way to reduce home loss,” Moritz said. 

In the last week, the Board of Forestry hosted one town hall in Ventura and another in Pasadena, both open to public comment, listening to questions at the latter for nearly five and a half hours. 

In Ventura, concerns were raised over the increases in urban heat and energy costs that would follow mass tree removal. Greg Rubin of Native Landscape Design, Inc. explained how some native plants can hold onto moisture for long periods of time and are needed to interrupt ember flows. 

The Pasadena meeting opened with a presentation of one man’s successful defense of his and his neighbor’s homes during the January fire in Altadena. He described the flaming crown of a palm tree acting as a source of embers dispersed to ignite multiple homes both near and far. Penny Sylvester, the Mayor of Agoura Hills, called for the Board of Forestry to give local officials the power to determine for their regions which vegetation is a threat, and which is not. She expressed concerns over the question of enforcement. 

At both meetings, the Board of Forestry showed a slide with the logos and names of their partners in forming their Zone Zero rules. In Pasadena, Dave Lefkowith, vice-president of the Mandeville Canyon Association, pointed out that the list consisted solely of fire departments and insurance companies: until now, it seems few if any scientists or academic institutions have been brought to the table in a meaningful way.

The presence of insurance companies is concerning, to say the least. If the rules are implemented in their current form, firefighters will be responsible for walking homeowners’ properties and providing information on how they can comply with the regulations. Homeowners will be responsible for modifying their landscaping. It will be almost impossible for everyone to keep the outer edges of their ever-expanding shrubs back exactly five feet. At the same time, insurance companies could fly drones over large swaths of homes at a time and judge five feet from aerial photography. Zone Zero presents a case where it is much easier to judge compliance than to comply. Imagine the worst-case scenario where a homeowner is trying to follow the rules but misses a tree branch by a couple inches and is then denied coverage by their insurance when their house burns down (possibly for a completely different collection of reasons). 

Summing Up Zone Zero

The Zone Zero rules are not built with the goal of decreasing home loss in wildland-urban conflagrations. If the goal was fire prevention and suppression, wouldn’t the science of firefighting be among the largest influences on how the rules are written? 

California must get more serious about addressing its wildfire problem. Let’s not worry about nitpicking the growth of our vegetation. Priorities should be based on what we know for sure, not on an arbitrary space limitation without significant scientific basis. 

Here is what the state should be prioritizing based on the science: demands for home hardening, building new homes and developments more responsibly (with respect to very high fire risk zones), removing specific highly flammable vegetation, and emphasizing the importance of yard maintenance. This means clearing dead and dying branches from trees and consistently removing accumulated leaf litter, which is dry and highly flammable. “If you keep [your yard] open enough and well-maintained enough [vegetation-wise] the plants there won’t ignite and burn your own house down,” Max Moritz said.

An important note is that maintenance is an ongoing practice and not so easy. A recent study explored how in most cases people do not keep up with their yard maintenance. Zone Zero seems like the ultimate reaction: if homeowners aren’t good at maintaining their vegetation, just mandate they remove it. This is an overstep in control, but there is something to be learned. The study’s authors suggest we “mitigate the need to mitigate.” It is time we renovate with fire-resistant materials and landscape with plants that are fire and drought-resistant and that require less maintenance. 

Montecito is particularly vulnerable to wildland-urban fires. The Local Responsibility Area for Very High Fire Hazard ranges from East Valley/Sycamore Canyon south to Coast Village. Everything north into the Santa Ynez Mountains is contained by the State Responsibility Area for Very High Fire Hazard. Zone Zero will affect both areas. If you live in Montecito, whatever is decided in the next three months will affect you, whether you like it or not. The Board of Forestry heard additional comments from the public on September 22 in Sacramento. Zone Zero rules will be revised through October with the formal rule-making process beginning in November. Whatever is decided will affect new construction immediately and existing homes within one-to-three years.  

Sources

California Assembly Bill No. 3074, Chapter 259, Statutes of 2020. “Fire prevention: wildfire risk: defensible space: ember-resistant zones.” Bill Text: CA AB3074, 2019-20 Regular Session, LegiScan, 29 Sept. 2020, https://legiscan.com/CA/text/AB3074/id/2210565

California Board of Forestry and Fire Protection. Draft Zone 0 Rules, 18 Aug. 2025, Board of Forestry website, https://bof.fire.ca.gov/projects-and-programs/defensible-space-zones-0-1-and-2

California. Executive Order N-18-25: Urban Conflagration. By Gavin Newsom, Governor of California, 6 Feb. 2025. State of California – Executive Department, https://www.gov.ca.gov/wp-content/uploads/2025/02/2025-2-6.Urban-Conflagration-EO-ATTESTED.pdf

Escobedo, Francisco J., Kamini Yadav, Onofrio Cappelluti, and Nels Johnson. “Exploring Urban Vegetation Type and Defensible Space’s Role in Building Loss during Wildfire-Driven Events in California.” Landscape and Urban Planning, vol. 262, 2025, article 105421. https://doi.org/10.1016/j.landurbplan.2025.105421

“Hardening Your Home.” Prepare for Wildfire: Hardening Your Home, CAL FIRE, 2025, https://www.fire.ca.gov/home-hardening

Keeley, Jon E., and Alexandra D. Syphard. “Twenty-First Century California, USA, Wildfires: Fuel-Dominated vs. Wind-Dominated Fires.” Fire Ecology, vol. 15, no. 24, 2019. https://doi.org/10.1186/s42408-019-0041-0

Knapp, Eric E., Yana S. Valachovic, Stephen L. Quarles, et al. “Housing Arrangement and Vegetation Factors Associated with Single-Family Home Survival in the 2018 Camp Fire, California.” Fire Ecology, vol. 17, no. 25, 2021. https://doi.org/10.1186/s42408-021-00117-0

Longcore, Travis. Re: Defensible Space Zone 0 and Vegetation/Trees. Email to Zone Zero Regulatory Advisory Committee, California Board of Forestry and Fire Protection, 26 Apr. 2025.

Marantos, Jeanette. “Proposed ‘Zone Zero’ Rules Would Remove All Plants Within Five Feet of Homes in Fire Areas.” Los Angeles Times, 15 Sept. 2025, https://www.latimes.com/lifestyle/story/2025-09-15/proposed-zone-zero-rules-would-remove-all-plants-within-five-feet-homes-fire-areas

Moritz, Max. Interview. Conducted by Asher Radziner, 19 Sept. 2025, via Zoom.

Zamanialaei, M., San Martin, D., Theodori, M. et al. Fire risk to structures in California’s Wildland-Urban Interface. Nat Commun 16, 8041 (2025). https://doi.org/10.1038/s41467-025-63386-2

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Zone 0

Zone 0 (0-5 feet) reduces the likelihood of structure ignition by reducing the potential for direct ignition of the structure from flame contact, by embers that accumulate at the base of a wall, and/or indirect ignitions when embers ignite vegetation, vegetative debris ,or other combustible materials located close to the structure that result in either a radiant heat and/or a direct flame contact exposure to the structure.

Zone 0 is the horizontal area within the first five feet around the structure and any outbuildings, attached decks, and stairs. The zone also includes the area under attached decks and stair landings. Zone 0 should incorporate a 6-inch vertical area between the ground and the start of the building’s exterior siding to be most effective.

Zone 0 is a critical component of structure defense and, when coupled with Zone 1 and Zone 2, is essential to providing effective defensible space.

Zone 1 

Zone 1 extends from Zone 0 (first 5 feet around a structure) to 30 feet around a structure and deck or to the property line if less than 30 feet. Zone 1 is designed to reduce wildfire risk by minimizing flammable materials and maintaining vegetation in a way that slows fire spread.

Requirements:

–Remove dead leaves, pine needles, and debris from your yard, roof, and gutters.

–Trim overhanging branches to at least 10 feet away from chimneys.

–Keep trees pruned to maintain spacing.

–Clear flammable vegetation and items from under decks, balconies, and stairs.

–Maintain space between trees and shrubs.

–Ensure outbuildings and propane tanks have 10 feet of clearance with no flammable vegetation nearby.

Creating and maintaining defensible space is crucial for wildfire safety, helping protect homes and firefighters.

Zone 2

Zone 2 extends 30 to 100 feet around a structure or to the property line if less than 100 feet. Zone 2 is designed to slow the spread of wildfire by reducing the amount of vegetation that could fuel flames.

Requirements:

–Mow grass to a maximum height of 4 inches.

–Create horizontal spacing between shrubs and trees.

–Remove dead vegetation and fallen leaves.

–Prune lower branches of trees.

–Ensure outbuildings and propane tanks have 10 feet of clearance with no flammable vegetation nearby.

This zone helps create a buffer that reduces fire intensity before it reaches a structure.

(Source: bof.fire.ca.gov)