By Kate Talerico | The Mercury News
In 1984, Mike Bradley bought a brown-shingled home on a quiet street in central Berkeley.
Forty years and three generations later, the Bradley family has grown — and so has their home. In 2009, the family built an addition, which Mike got when his son, Michael “Casey” Bradley, moved into the main house with his wife, Daphnée St Pierre, and their two children.
Last year, Mike’s daughter Kelly decided to move from Oakland to Berkeley, seeking to be closer to the rest of the family. After a few weeks of fruitless house-hunting around their neighborhood, Casey had an idea: Why didn’t they construct a house for Kelly on their existing lot?
“We already have this family compound,” Casey said. “Why not build it ourselves?”
Within seven months, Casey — a former planner for the city of Oakland who now works in real estate development — built a 1,000-square-foot, two-story accessory dwelling unit on the back of the lot for about $350,000. That brings the total units on their 8,666-square-foot lot to three (four, if you include the tree house).
In recent years, the state of California has seen an explosion in ADUs, also known as mother-in-law units or backyard cottages. In 2023, one out of every five homes built in the state was an ADU, according to recently released state data. Only three years ago, they represented just one in every 10 new units.
“There’s a generation that has a lot of wealth right now that can build these properties in their backyard and ease the pain of another generation,” said David Gunderman, an Oakland-based real estate agent who helps advise homeowners about building ADUs. “I do think, if anything, we’re on the front end of this wave.”
Since 2017, the California state Legislature has passed several bills lowering the ADU building barriers. Most notably, AB 68, authored by San Francisco Democratic Assemblymember Phil Ting and passed in 2019, sped up the approval process from 120 days to 60 and prohibited local officials from imposing requirements around lot size and parking. AB 881, passed the next year, prevented communities from requiring the owner to live on the property, opening up the possibility for landlords to build ADUs on their rental properties.
To address its decades-long housing shortage, housing advocates say California needs to build all types of housing — more single-family homes, more tall apartment buildings, more affordable houses, more everything. But supply is constrained by the lack of open land close to existing infrastructure and jobs, as well as strict local zoning laws that limit what can be built in infill areas.
“Our biggest challenge in California is that so much of our zoning is for single-family homes, which makes it next to impossible to build any new housing,” Ting said in an interview. “This is the one housing product that you can actually build in these single-family neighborhoods.”
In 2023, California added more ADUs than ever
Last year nearly one in five homes added were an accessory dwelling unit, also known as ADUs or mother-in-law cottages.
Source: California Dept. of Finance
In the five-county Bay Area, ADU construction has more than doubled in the last four years, going from 1,179 new units in 2020 to 2,761 units in 2023. The units are especially popular in places like Berkeley and San Jose, where older homes often come with large lots, well-positioned to accommodate an ADU.
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