An accessory dwelling unit built behind a home in Berkeley. Credit: Courtesy Dan McDunn

Local regulations limiting the number of backyard cottages and in-law units that can be built in the Berkeley Hills violate state housing law and must be changed, California regulators told the city this month.

The City Council adopted the restrictions in January over the objections of opponents who said they conflicted with a 2019 state law for accessory dwelling units, as the homes are called. Now the council will have to decide whether to amend Berkeley’s ADU regulations to comply with the law or challenge California’s Department of Housing and Community Development over the restrictions.

Berkeley’s regulations allow accessory units to be built throughout the city. But whereas homeowners in the flatlands can build two such units on the same property — both a detached cottage and a “junior ADU,” such as a basement apartment — they are only allowed one accessory unit on properties that lie in areas Berkeley classifies as Very High Fire Hazard Severity Zones. Units in the hillside fire zones are also subject to tighter square footage and height limits than those elsewhere in the city.

The state’s ADU law requires cities to let homeowners build two accessory units on the same property. However, Councilmember Susan Wengraf, who represents much of the Berkeley Hills, contended the city could limit them to one because of a separate provision of the law allowing local governments to consider traffic and safety when setting their rules.

The city classifies neighborhoods throughout the Berkeley Hills as Very High Fire Hazard Severity Zones, and limits efforts to build ADUs in those areas. Credit: City of Berkeley

Wengraf pushed for the limits out of concern that allowing more homes to be built in the hills would add to the difficulty of evacuating residents along the area’s narrow, winding roads during a wildfire, citing the deadly traffic jams that trapped victims of the 2018 Camp Fire and 1991 Oakland-Berkeley Firestorm.

David Zisser, an assistant deputy director for local government relations and accountability at the Department of Housing and Community Development, struck down that reasoning in an Oct. 17 letter to Berkeley Planning Director Jordan Klein. The city had justified the limits by citing a 2021 UC Berkeley simulation of a wildfire evacuation in the hills, but Zisser wrote the study did not specifically analyze how new accessory units might affect evacuations.

“While HCD is sympathetic to concerns about fire safety and the need to ensure adequate evacuation in the event of a fire, the city has not adequately demonstrated that new ADUs will actually impact public safety,” he wrote.

Zisser added that Berkeley “must amend this prohibition to explicitly permit applications” for two units on the same property.

Klein acknowledged that the city had received a letter but declined to comment Wednesday.

Wengraf said in an interview that state regulators are being too inflexible with the ADU law and should have provided more leeway for cities that are at risk from wildfire to limit construction.

“My sense from HCD is that they are making these decisions not based on actual knowledge of the area — they’re making it just based on the way they wrote their [laws],” Wengraf said. “They’re not on the ground, in reality, looking at the situation, which is very frustrating.”

Cities across California are grappling with how to balance requirements that they produce more housing with calls to limit the number of people living in areas that are most at risk from the state’s increasingly destructive wildfires. Wengraf said she hopes to work with other California cities to lobby for changes at the state level that would restore some of their authority to limit density in fire zones.

Critics view some of those efforts with skepticism, though, charging that they look like the latest justification for blocking housing in wealthy and exclusive communities that have long resisted it. Those concerns were raised when the Berkeley City Council adopted the ADU regulations for the hills, which include several wealthy neighborhoods.

Pro-density advocates and some councilmembers argued it didn’t make sense to tighten limits on ADUs — and risk a conflict with the state — when those units would add relatively few homes and the city still allowed other forms of development in the hills, like new single-family houses. Councilmember Lori Droste cited planning department data that showed only one homeowner in the hills had sought approval for two accessory units on the same parcel in two years.

At the January meeting where the regulations were adopted, Droste and three other council members supported a motion to allow two ADUs on each property. It fell one vote short of passing, and the council approved the one-unit limit.

“Nobody is trying to spur massive development in fire-prone areas of the hills,” Droste said. “I just think that we need to write consistent, clear and objectively applied standards that comply with state law.”

The Department of Housing and Community Development has stepped up efforts to enforce housing laws as Sacramento produces a flurry of legislation prompted by the housing crisis that requires cities to plan for more homes and restricts their authority to reject projects. Zisser’s letter warned Berkeley that the housing agency would inform Attorney General Rob Bonta — who formed a “strike force” last year to investigate potential violations of housing laws — if the city didn’t bring its ADU ordinance into compliance.

Berkeley has until Nov. 17 to respond to Zisser’s letter.

Wengraf said she wants to discuss the issue more with Klein and the city attorney’s office before deciding whether to adopt the state’s two-unit limit, or try to challenge the housing agency over the regulations. Droste said she did not believe such a challenge would succeed.

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,...