ADUs Leading to Intergenerational Bay Area Living

Homeowners are building in their homes and backyards for aging parents and grown kids.


Larson Shores Architecture and Interiors dubbed this demonstration unit “The Bungalow.” It got rave reviews at West Coast Green, the San Francisco trade show for sustainable building. It’s small and cozy at 500 square feet.

Photo by Mark Luthringer

When Mella Trier’s husband died in 2015, her son and daughter urged her to move to Berkeley, where they live with their children. After pondering the options, including renting, Trier, 84, is leaving her three-bedroom home in suburban Belmont for a 597-square-foot accessory dwelling unit being built in her daughter’s backyard.

The arrangement is a time-honored one. Long known as “granny flats” or “backyard cottages,” accessory dwelling units are small, self-contained units with their own entrances, cooking, and bathing facilities on the site of larger, single-unit dwellings. In the face of the East Bay’s housing crisis, the option is becoming more popular as one way to cope.

Size requirements vary, but “we have done two-bedrooms from 650 to 1,200 square feet, and the current state law allows you to go up to both of those sizes,” said Kevin Casey, founder of Berkeley’s New Avenue Homes, which has built hundreds of accessory dwelling units in the state and the country.

Photo by Mark Luthringer

The units can be simple or elaborate and vary in size. Room & Board chose furnishings that fit the demonstration unit space without overwhelming.

At first Trier considered renting a house in Berkeley near her daughter and son, who live about 2½ miles apart. The family is close, and she enjoys spending time with her daughter, son-in-law, and granddaughter, as well as her son, daughter-in-law, and their son.

“I knew I didn’t want to own a home again, because it’s been work” keeping up her Belmont home, Trier said.

“But then, we heard about ADUs,” she said. “Our architect had an open house of a smaller unit than I have. Mine will be about 600 square feet, but this one was about 425 square feet. I was impressed with how efficient it was.”

Living right in her daughter’s backyard will make it “more easeful” for Trier to spend time with her granddaughter baking chocolate chip cookies and passing on Trier’s mother’s banana bread recipe. She’ll be able to lend a hand to her daughter and son-in-law with child care, and as she ages and needs more help, her family will be right on the spot, she said.

“When I thought about it, if I rented my own house now, maybe as I get older I might need more care and need to be even closer, so I thought, ‘Well, why not now? Why make two moves?’ ” Trier said.

When Trier moves into the unit — scheduled to be completed in August — she’ll be steps away from her daughter, Naomi Fair, son-in-law, 9-year-old granddaughter, and their 1,100-square-foot, two-bath home.

“This makes it so my mom can live independently on our property. We’re looking for both intimacy and privacy,” Fair said. “Even if we had an extra bedroom, which we don’t, we would be living on top of each other.”

Trier said she’s looking forward to living in her daughter’s neighborhood, explaining, “Where I live now is a suburb. When I walk out the door, I’m always getting into my car, whereas there will be things I can walk to in Berkeley.”

Not all accessory dwelling units are in backyards. They can be built within the main house — but the same person owns them. More Californians are building these units, thanks to state laws that make it easier in response to the ongoing housing crisis locally and statewide. Across the state, cities saw a marked increase in backyard cottage applications and issued permits in 2017, according to the Terner Center for Housing Innovation at the University of California, Berkeley. In 2015, there were just 33 permit applications in Oakland. By Nov. 1, 2017, the city had received 247 applications in that year alone — more than seven times the volume from two years prior. In San Francisco, 41 such units were permitted in 2015, zooming to 593 in 2017.

Photo by Mark Luthringer

Carrie Shores of Oakland’s Larson Shores Architecture and Interiors designed Mella Trier’s backyard unit. The firm got interested in accessory dwelling units eight or nine years ago, one of the first to take an interest in the tiny dwelling spaces.

“We started this as a passion long ago when the process was much harder. We did it in our spare time,” Shores said. Now the firm regularly designs such units. Shores worked closely with both Trier and her daughter to design the backyard unit.

“I had input about what was important to me. I wanted a fully functional kitchen. I do like to cook and socialize over food,” Trier said.

Accessory dwelling units can be simple or elaborate. Trier’s is L-shaped with an open kitchen/living/dining area in the longer part of the L, and a laundry area, bathroom, and bedroom in the shorter part. Homey touches include hardwood floors, quartzite countertops, a kitchen peninsula, and a large dining table with built-in benches with storage.

Across the state, accessory dwelling units cost an average of $156,000 to construct, according to the Terner Center. In comparison, the average cost per unit of affordable housing statewide is $332,000, and even higher in major metropolitan areas: The cost is $591,000 per unit in San Francisco. In Shores’ experience, the cost of building an accessory dwelling unit is around $500 a square foot for constructing a free-standing backyard unit or about $250,000 for a 500-square-foot house.

“If you are building a one-bedroom and you can rent it out for $2,500 a month, the return is great,” she said.

There’s another increasingly popular approach, she said: “A lot of people will take out a home equity line of credit on a home they have owned a long time and fund the in-law [unit], and the parent or adult child moving in pays off the equity line. This is a lot lower than what they would pay for a market rate rental.”

Bringing an older family member closer is just one of many reasons to add an accessory dwelling unit. Now some parents are building them as homes for grown children who can’t afford to pay astronomical rental prices.

Nick Wolf, 28, is an example of this practice. He has a successful company, Nick Wolf Photography, in the East Bay, but the 5-year-old business doesn’t pay enough for him to afford to rent here. In March, the median rent was $3,600 in Berkeley and $2,800 in Oakland, according to Zillow. Five or six years ago, he moved in with his parents, who remodeled a basement room in their home in Oakland’s Temescal district into a studio for him.

“The long-term goal was for me to save enough money to invest in buying a property, but eventually I realized I would never be able to buy a house” because of the skyrocketing home prices, Wolf said. The median price of a home in Oakland is $760,157 as of March, according to Zillow.

Then, “I realized I could invest in a small ADU and live there and that would only raise the property value of my parents’ home,” Wolf said.

At 700 square feet, the under-construction unit will seem spacious, with four rooms, an open living room/kitchen space, a bedroom, a bathroom, and a small office with pullout guest bed.

“My parents were able to refinance their mortgage and bundle in a loan” to build the unit, he said. He will make the monthly payments on the loan, which are far cheaper than the price of renting a house in Oakland, he said.

“I feel very lucky to get along with my family so well. We are very close. I feel blessed that I am able to stay living close to them,” Wolf said. “This housing crisis is crazy, and it’s not going to get any better. I saw an opportunity and I took it.”

Photo by Mark Luthringer

To make building an accessory dwelling unit easier, new state laws regarding the units were approved in 2016, going into effect Jan. 1, 2017. Local municipalities had 60 days to comply or state law would take over.

“The cities could put in additional elements or limit the square footage, but there were additional things the cities couldn’t mess with,” Shores said. For example, if the interior of the main dwelling unit was not equipped with sprinklers for fire prevention, cities couldn’t mandate that the accessory unit be sprinklered, she said. The changes streamlined planning permits to over-the-counter approval, avoiding lengthy and costly hearings, and eased parking requirements. For units within a half mile of a major transit line, parking requirements were eliminated. The changes shave off about four months from the permitting process and about $4,000 in fees, Shores said.

“Before proceeding, you need to check with your local municipality,” Shores said, because different cities have different rules.

To begin the design process, a homeowner first hires a designer — an architect or a contractor, “someone to develop the drawings with you,” Shores said. “Then you have to get your over-the-counter planning approval. Your drawings are reviewed by the building department. The building department approves the drawings and issues a permit.”

While Shores is constructing an accessory dwelling unit within a house in Oakland, she said more people opt for backyard units. “If you build something in the main home, you might trigger seismic upgrades in the main structure. You also have requirements such as fire separations between floors that might add another level of expense.”

Other than that, if you have the space and the house has the legal height limit, you’re good to go. Shores’ firm converts garages or encloses rooms within homes to create such units, which must have their own entrance, cooking, and bathing facilities.

Both an independent unit within a home and freestanding units are energy-efficient, Shores said. “It’s a more green way of growing. It’s using existing land, existing infrastructure, police, schools. Instead of building large high-rises, you’re filling in existing land,” she said.

“I like the idea of having a smaller footprint and also having less maintenance to do,” said Trier. “It’s such a nice way of keeping family together, three generations. I feel a little bit like, ‘Gee, I’m in on the beginning of a trend.’ ”

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