Berkeley’s City Council voted to limit efforts to build accessory dwelling units in the Berkeley Hills, citing wildfire risk in the area. Credit: Clara Mokri Credit: Clara Mokri

Driven by the fear that allowing even slightly more dense new housing in the Berkeley Hills could make it harder to safely evacuate residents during a wildfire, the City Council has approved new regulations limiting construction of accessory dwelling units in those neighborhoods.

The new policy was adopted early Wednesday morning following hours of discussion over the objections of critics who charged that it will have the effect of blocking new housing in many of Berkeley’s wealthiest neighborhoods while doing little to reduce fire danger.

The regulations don’t ban backyard cottages in the Berkeley Hills altogether. Instead, they limit homeowners to building just one accessory unit — either a detached cottage or an internal “junior ADU,” such as a basement apartment — while also setting the lowest size limits for the units allowed under state housing laws. Cottages can have no more than 800 square feet of space, and internal units can’t be more than 500 square feet.

The rules will apply in the areas Berkeley classifies as its Very High Fire Hazard Severity Zones. Homeowners outside of those zones can build both types of ADUs on the same parcel under a separate set of regulations the council approved last week, which also allow for bigger cottages.

“Limiting the number of ADUs, and restricting the size of ADUs, in the very high hazard zone is one step in the right direction,” Councilmember Susan Wengraf, who represents much of the hills and co-authored the regulations with Councilmember Sophie Hahn, told her colleagues during the meeting that began Tuesday evening. “I’m asking for your help to try to figure out how to keep the residents of Berkeley safe.”

Berkeley’s limits on new ADUs will apply in Fire Zones 2 and 3 on this map. The rest of the city is subject to less-restrictive ADU regulations that were approved last week. Credit: City of Berkeley

Berkeley officials have been working for months to develop new regulations for accessory units in the wake of state laws that require cities to streamline their approval and limit local authority to reject cottages.

As California’s wildfires grow more destructive — in part because of both climate change and sprawling development that has put more people and homes in fire-prone areas — Wengraf and others contend cities should be able to limit attempts to build in places that are most likely to burn.

Officials worry the East Bay Hills’ maze of narrow, winding streets will quickly become gridlocked if residents need to flee from a fast-advancing wildfire. Some speakers at the council meeting referenced the traffic that trapped many victims of the 2018 Camp Fire in Paradise, and Wengraf played dramatic footage from the 1991 Oakland-Berkeley Firestorm of people being forced to flee on foot because their cars were backed up on the hilly roads.

“There’s no such thing as an orderly, peaceful, choreographed evacuation – it’s chaotic, it’s driven by fear and panic, and everybody is racing for their lives,” Wengraf said. “That’s what we’re facing in Berkeley.”

Wengraf described allowing one ADU as a “compromise” that could let hills residents who have already built basement units or cottages without permits to bring them up to code. Permitting two new units on each parcel, she said, would add too many more people and cars to a wildfire evacuation.

Oakland’s City Council in December adopted slightly less-restrictive ADU rules for its hills, limiting only homeowners who live on narrow roads in the fire risk zone to one accessory unit. Residents in those areas who live on streets that are at least 26 feet wide can build up to two new units.

But with thousands of people living in the hills already, some Berkeley City Council members doubted that allowing more accessory units would really ratchet up the danger. Councilmembers Rashi Kesarwani and Lori Droste cited data from city staff that only one homeowner in the area, subject to the new regulations, had sought a permit to build two accessory units on the same parcel over the past two years.

“I just don’t think this is a direct and clear way to actually address fire risk,” Kesarwani said.

During public comments on the proposal, several speakers noted Berkeley is not similarly restricting other projects that add new homes and people in the hills.

“If we allow the development of brand-new single-family homes and the expansion of wealthy people’s hillside residences, but we don’t allow more-affordable ADU development, then that is not fire safety – that is NIMBYism,” resident Sarah Bell said. “Let’s not unfairly target ADUs.”

Dozens of other members of the public spoke in favor of tighter limits, and rejected the idea that they were seeking to block housing under the guise of fire risk.

“This isn’t a NIMBY or YIMBY issue,” speaker Harald Leventhal said. “This is, put simply, a life safety issue.”

As the clock ticked toward 1 a.m. Wednesday, the council voted to approve the new regulations in a harried sequence. Hahn motioned first to approve her and Wengraf’s proposal — then Kesarwani responded with a motion of her own for a less-restrictive policy that would allow homeowners throughout the hills to build two ADUs on the same parcel.

Advocates for looser restrictions on new housing warn the regulations written by Hahn and Wengraf could be challenged in a lawsuit, because the state’s ADU law requires cities to let homeowners build both an internal and external unit on the same parcel. Wengraf and Hahn say their regulations will stand up to such a challenge, because of a separate provision in the same law allowing cities to consider “the impacts of traffic flow and public safety” when regulating ADUs.

After a flurry of questions about Kesarwani’s proposal, the council initially voted to approve it by a 5-4 margin, with Councilmember Kate Harrison and Mayor Jesse Arreguín joining Hahn and Wengraf in opposition. Moments later, though, Councilmember Ben Bartlett said he had cast his “yes” vote erroneously — amid the confusion over the dueling proposals, he’d mixed up which of the resolutions was before the council.

The members took another vote, and a “no” from Bartlett flipped the result. With Kesarwani’s proposal rejected, the council then approved the regulations written by Hahn and Wengraf, along with a referral from Droste for city staff to study other efforts to reduce wildfire risk, such as improving vegetation management and restricting parking on certain narrow streets.

In an interview Wednesday, Kesarwani said she was disappointed the council “could not agree to do the bare minimum when it comes to complying with state ADU laws in the high-opportunity neighborhoods in the hills.”

Bartlett, whose swing vote on the regulations proved pivotal, described thinking through the issue by asking what the consequences would be if the council’s choice was the wrong one. If the policy was too restrictive, he reasoned, the low demand for building ADUs in the hills would mean losing out on a relatively small number of new homes.

On the other hand, Bartlett said, “If we’re wrong about fire (risk), we lose more than a few apartments – we lose lives.”

“I’m not prepared to say no to someone’s request for safety,” he added.

Nico Savidge joined Berkeleyside in 2021 as a senior reporter covering city hall. Born and raised in Berkeley, he got his start in journalism at Youth Radio as a high-schooler in the mid-2000s. Since then,...