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Vegetation creeps over a shed in the Berkeley Hills. State rules are in development that will take a near-zero tolerance approach to anything combustible in the area closest to homes and structures. The new “Zone 0” regulations are set to take effect for new construction in January 2023, and all other dwellings one year later.  Credit: Ximena Natera, Berkeleyside/CatchLight

Charlie Bowen has a problem. It’s not immediate. She’s not losing sleep over it. But in a little over a year’s time, Bowen knows she’ll need to do something about it. 

If not, she could be breaking the law. 

Part of Bowen’s problem, however, is that the solution could also break a law, or at least require a permit not to do so. Call it the proverbial rock and hard place. Call it a clash of good intentions. 

Bowen, a resident of the Berkeley Hills, has an oak tree growing next to her house – a volunteer oak, sprouting up on its own, perhaps planted by a squirrel or a heavy wind.  

Living in one of Berkeley’s, and the state’s, high fire risk zones near the edge of Tilden Park means Bowen must meet wildland fire prevention defensible space requirements. Her property is subject to regular city inspections, and passed this year.  

A trespassing oak growing 4 feet from Charlie’s Bowen’s Berkeley house in a high fire severity zone requires constant trimming to keep its branches from pushing against the structure, a known fire risk. The tree’s location makes it subject to a new state defensible space law, effective in 2024, but pruning or removing it goes against a city law, effective in 2024, but removing it goes against a city law. Credit: Charlie Bowen

The oak tree in question, the culprit, is legal now. But in a little more than a year’s time, it’s vulnerable to a new state defensible space regulation, called Zone 0, stretching 5 feet from the base of structures in areas prone to fire. Final details for Zone 0, also called the ember-resistant zone, are still being hammered out in Sacramento. But based on preliminary guidelines, any vegetation permitted will likely need to be fire resistant, well-spaced and not too large. Single trees may be OK, if trimmed. Hardscaping — stone, cement, gravel — is preferred.  

Bowen, who strives to be fire compliant, is fine getting rid of the tree. She’s not attached to it and doesn’t like the constant work of cutting it back. But her problem is that to do so is restricted by a city ordinance. Coast live oaks are protected by Berkeley, requiring a special permit to cut down. Her vigilant pruning may also require a permit. 

Bowen’s case is likely not isolated. It’s one example of the challenges that lie ahead with the enforcement of Zone 0, set to take effect for new construction in January 2023, and all other dwellings one year later. 

To wildfire prevention experts, restricting plantings and other combustible material in Zone 0 is a critical measure in trying to prevent buildings from burning. They also know it will take a new way of thinking about landscaping, as well as lots of work.

“This is the big one; Zone 0 is by far the biggest adjustment to defensible space,” said John Morgan, Cal Fire’s deputy chief of wildfire prevention.

When Bowen’s house was inspected by the city fire department earlier this year, she asked about the oak, which she needs to trim regularly to stop it from brushing against her house, a known fire risk.

“The inspector said I should first talk to the city and see if they would agree that it should be removed for fire purposes,” she said, “And then, he said, if the city said no I should quietly contact him and he might be able to write me out a [fire prevention] violation notice or something that would make the city agree that the tree could be cut down.” 

Bowen hasn’t yet taken any additional steps to deal with her predicament. 

Receptive fuel bed

Final details for Zone 0 are still being hammered out in Sacramento. But based on preliminary guidelines, any vegetation permitted will likely need to be small, well-spaced and not too tall. It will mean a major change for most homeowners in the hills. Credit: Ximena Natera, Berkeleyside/ CatchLight

Cal Fire is responsible for regulating wildfire statewide, including determining fire hazard severity zones based on a number of factors such as weather, vegetation, topography, structure  density and fire history. (The fire hazard zones are currently being updated, with draft results expected for public review in the fall.) 

The state fire agency also has jurisdiction over wildfire prevention laws. Local fire agencies such as the Berkeley Fire Department can set regulations that are stricter than the state’s, but not weaker.

Read more about defensible space laws in the Berkeley Wildfire Guide

Defensible space laws, which apply in the state’s two highest fire hazard zones, establish specific prevention requirements for two property zones, Zone 1, extending 30 feet out from structures, and Zone 2, 100 feet out.

Soon, Zone 0 will be added as the law — taking a near-zero tolerance approach to anything combustible in the area closest to homes and structures. “The ember-resistant zone is currently not required by law, but science has proven it to be the most important of all the defensible space zones,” says Cal Fire’s website. 

The CalFire model of defensible space uses three zones, called 0, 1 and 2. Credit: Liz Bradford

State lawmakers added Zone 0 in 2020 Assembly Bill 3074, based on data showing how embers that collect next to buildings during wildfires are a major source of structure fire. The law encourages collaboration between fire agencies and residents to achieve compliance, being mindful of the cost to property owners and with enforcement actions as a last resort.

Morgan described the area near buildings as a “receptive fuel bed.” Embers land with nowhere to go, smoldering and building up heat, which can ignite the structure. Wind makes it worse. 

“Some of these embers are substantial; if the first 5 feet are ember resistant, those homes have a much greater chance of survival,” he said.

During a wildfire, embers can land near structures with nowhere to go, smoldering and building up heat, which can ignite the structure. Credit: Ximena Natera, Berkeleyside/ CatchLight

To help people prepare, Cal Fire is ramping up its education and outreach efforts, with more to come, Morgan said. 

The California Board of Forestry and Fire Protection is charged with writing the final Zone 0 regulations, including what’s allowed and not allowed in the area.

The board has been deep in hearings and information-gathering. A few outcomes are expected, Morgan said, based on these discussions and Cal Fire’s current voluntary guidelines for the area, which advise hardscaping, removing dead or dying plants (including leaves or needles), and no mulch. Zone 0 includes spaces under decks and porches.

The law will also likely forbid wood fences from touching structures, Morgan said, as they’re a great conveyer of fire straight to a building. A 5-foot gap or metal gate can stop a burning fence from reaching a house, Morgan said.

It’s also likely that if any vegetation is allowed in the zone, it must be highly fire-resistant, well spaced out, and not high, he said. Ladder fuels such as Ivy or Bougainville up the sides of buildings may be restricted.

These are educated guesses or speculation until the law’s language is finalized.

Meanwhile, Morgan said, Cal Fire hopes affected property owners will start working now on creating Zone 0s, especially as fire season is here. For some, the task will be time-consuming and expensive.

“Encouraging is a great word,” Morgan said, “We cannot force people [today] but we certainly encourage homeowners to maintain an ember-resistant zone within that first 5 feet.” 

Berkeley watching closely

“This is the big one; Zone 0 is by far the biggest adjustment to defensible space,” says John Morgan, Cal Fire’s deputy chief of wildfire prevention. Credit: Ximena Natera, Berkeleyside/ CatchLight

The Berkeley Fire Department is closely watching the new regulation and providing feedback to the state, said city fire marshal Steven Riggs. 

The city’s defensible space inspection program, which today covers 8,600 properties, works closely with residents to bring compliance, he said. All properties have been inspected this year, with 6,000 passing as of early June.

Several California communities already have some version of Zone 0 on the books. A list provided by John Morgan, Cal Fire’s deputy chief of wildfire prevention, includes: 

 The city’s wildland fire efforts, including inspections, are ramping up  with support from the city’s Measure FF.

State wildfire regulations tend to be based on rural or mountain areas with coniferous forest, which don’t always easily transfer to urban or suburban communities, Riggs said. “The wildfire fuel conditions in our region are going to take some time to mitigate and the science behind defensible space continues to evolve.”

He notes the cost of tree removal, in the thousands of dollars depending on size and location.

When asked about Bowen’s oak dilemma, Riggs and Chris Pinto, a Berkeley Fire assistant chief, said at first glance, they don’t view coast oaks as posing as much of a fire threat as many other species. 

“It’s true that the tree canopies may need to be modified to some extent to limit foliage in Zone 0,” they said in a jointly written email. “We are looking to balance fire safety with other goals including: Heritage trees, energy conservation, water use reduction, and overall climate change resiliency.” 

But they acknowledge Zone 0 base standards will ultimately boil down to what the state decides. 

Under current defensible space law, tree branches aren’t allowed to hang over roofs, and must be kept 10 feet from chimneys, as well as from the branches of other trees. 

Bowen said even if the uninvited oak next to her house is allowed when Zone 0 is effective law, she prefers it gone. It drops tons of prickly dry leaves, spreads acorns that root and need yanking up, and creates poor growing conditions for other plants. 

It’s also becoming large quickly, she said. 

“I’d plant a smaller species of tree much further from the [house] wall. I just haven’t made the effort to find out what I might do to somehow apply/request permission to cut the tree.” 

A possible carrot

Homes, like this one, that are already complying with Zone 0 are rare in the Berkeley Hills. Credit: Ximena Natera, Berkeleyside/CatchLight

If regulations are the stick behind arduous wildfire prevention management, the Insurance Institute for Business & Home Safety hopes it might offer a carrot. And one that is available now.

The South Carolina-based institute, which is a science and data source for the insurance industry, recently unveiled a new Zone 0 voluntary certification program for property owners in high wildfire hazard areas. 

It’s called Wildfire Prepared Home.

To become certified, which costs $125 and requires an inspection, property owners can’t have anything growing in the area extending 5 feet from structures, which the institute calls a near-home noncombustible zone.  

“Our program does go beyond what is currently the guidance,” said Ian Giammanco, senior director of data and analytics at the institute.

“We require no combustibles of any kind. Zero vegetation.” Some potted plants are allowed.

Data from the institute’s studies show that “this is where embers like to accumulate and they like to ignite stuff,” Giammanco said.

In addition to a noncombustible zone, certification requirements include having a Class A fire-resistant rated roof, noncombustible gutters and downspouts, and six inches of noncombustible vertical material from the ground up on all sides of a building — among several other steps.

The program is so far available only in California. It launched a few weeks ago in the town of Paradise, which was nearly decimated in the 2018 Camp Fire, the deadliest and largest in state history. 

The Paradise City Council voted to require all homes in the city to get the institute’s basic certification. It’s also seeking grants and other financial assistance to help homeowners. Since much of the community burned, complying with Zone 0 won’t be as difficult or expensive as in established areas with mature trees and landscaping, such as Berkeley and most of the East Bay hills, Giammanco acknowledged. 

A second level of certification is also offered by the institute that requires more extensive home hardscaping, such as installing fire-resistant siding and windows.

The institute’s hope, Giammanco said, is that insurance companies will be more willing to cover homes in high fire risk areas with just the basic certification, and at lower prices.

“That’s the general goal,” he said, saying the approach has worked in other areas prone to natural disaster. “The hope is the program does provide that pathway to a private insurance market. “We’ve seen the same thing with hurricanes on the gulf coast.”

As many residents painfully know, it’s increasingly difficult to get property coverage in high hazard fire areas, and when it’s available, it’s costly. 

Expanding the insurance market through prevention programs like this one takes time, Giammanco said.

“With the rapid increase of risk, we have to find that path,” he said. “We have the science to bring it to bear; time will tell. This is a marathon – unfortunately.”


The image illustrating defensible space is adapted from the Wildfire Home Retrofit Guide (publication #SP-20-11) with permission from University of Nevada, Reno Extension and the Living With Fire Program.

Freelancer Catherine "Kate" Rauch has been contributing to Berkeleyside for several years, and also happens to live in Berkeley, near downtown. Her work as a journalist has encompassed everything from...