In 2019, Susan and Chuck Webb relocated from Bowling Green, Kentucky, to Berkeley, California, to be closer to their daughter and grandson. The retired couple soon realized they’d need more space than their century-old, 1,300-square-foot craftsman bungalow could provide in order to spread out, host out-of-town visitors and, perhaps eventually, accommodate a live-in caretaker.

Around the corner, a young professional couple likewise needed more space than their own similar-sized craftsman offered. Anticipating having children of their own, Julie and Joe wanted to be able to provide seasonal lodging for Julie’s retired parents, who live most of the year in in Hawaii.

Both couples decided to supplement their homes with backyard ADUs designed and built, incidentally, by the same local company: Type Five. The new structures are situated within 100 feet of each other—and although they vary in design, cost, and square footage, they both signify the growing embrace of ADUs as practicable multifamily housing solutions.

Susan and Chuck’s Studio

Back in Bowling Green, where housing costs 28 percent less than the national average, Susan and Chuck were used to living in a home twice the size of their new digs; and with Berkeley’s median home sale price at around $1.4 million, the new neighborhood was a big change, too.

“Almost every house on the block has two bedrooms and one bath,” says Susan, a retired art teacher. “And there are lots of shared units to help cover costs and meet the need for housing.”

The couple had work done on their new home, including a bathroom remodel, before moving in. Once settled, they considered extending the house or annexing the original detached garage, which Susan says “was never used much, and was literally falling apart.”

$5,277 General Construction Fees	$7,400 Demolition & Rubbish Removal	$24,000 Concrete
$45,250 Wood, Plastics, & Composites	$12,700 Thermal & Moisture Protection	$15,209 Windows & Doors
$15,800 Finishes	$5,039 Kitchen & Laundry Appliances	$12,000 Casework
$17,000 Plumbing	$11,000 HVAC	$19,000 Electrical
$6,595 Building Permits
Grand Total: $196,270

But after consulting a couple of architects, they learned the cost of a garage renovation would far exceed their budget—as would an addition to the house itself. One suggested looking at prefab ADUs—and during the pandemic, as Susan was researching online, she came across a local ADU design-build firm that combines prefab with basic on-site construction.

Type Five uses what cofounder Aleksis Bertoni calls a “site-build modular” design and construction system that lets clients participate in their projects through a streamlined process with a transparent budget.

“As both architect and general contractor, we’ve honed a system that easily allows for changes to everything from the building footprint and layout to room shapes, colors, and many other design features,” says Bertoni.

For Susan and Chuck, that system helped produce an all-electric 300-square-foot studio with an integrated folding wall bed; a minimalist kitchenette with a two-burner induction stovetop, built-in concealed range hood, and under-counter refrigerator; and a compact bathroom with marble sink and walk-in shower.

The ADU is connected to the home’s rooftop photovoltaic panels to help minimize costs. In fact, the ADU’s total cost of $196,270 was less than the couple’s bathroom remodel—and the unit regularly proves its utility.

“I use it as an art studio when I’m working on a project, and with the Murphy bed, it’s really easy to set up my table and get to work,” says Susan. “Our friends can visit and stay here comfortably and see the sights. Our eight-year-old grandson has a place to retreat when he comes over, and his mom stayed here while having work done at her place.”

The only hiccup in the process was getting the windows, which took about three months because of supply-chain disruption issues. But the end result was clearly worth the wait.

“Even compared to the old garage, it feels so much bigger with these big windows,” says Susan.

Julie and Joe’s One-Bedroom

The windows are actually what convinced Julie and Joe, who were themselves considering cheaper prefab options, to contact Type Five. “We saw this beautiful unit in the neighborhood during an open house event, and even though we were in this very small space, the windows made it feel really open,” says Julie.

Their project was the product of a long-planned partnership with Julie’s parents. “We bought the property, and they would pay for the ADU, which made it possible,” says Julie. “But there would be joint decisions.”

The unit had to match the house and blend with the neighborhood, and they wanted it to have high ceilings and large windows. “But we thought the windows shouldn’t look onto the main house, so that the unit would feel more separate,” says Joe.

$15,400 Demolition & Rubbish Removal	$25,000 Concrete	$34,000 Wood, Plastics, & Composites
$13,000 Thermal & Moisture Protection	$19,449 Windows & Doors	$30,000 Finishes
$6,561 Kitchen & Laundry Appliances	$10,000 Casework	$33,200 Plumbing
$10,800 HVAC	$22,320 Electrical	$9,000 Building Permits
Grand Total: $228,730

These considerations, among others, guided plans for an all-electric 400-square-foot, one-bedroom, one-bathroom ADU clad in soft blue plank siding with white window trim (to match the main house) and a red roof.

“My mom really leaned into it,” says Julie. “She wanted French doors for the front door, which was a game-changer in terms of making it feel like you’re really in the garden.”

Indeed, the double doors open to a living space furnished with a sofa and dining table—and a fully functional contemporary home.

“My parents actually don’t like modern style at all, and at first, they were like ‘why are there no baseboards?’ but then they spent time in it and saw how it made sense for the small unit,” says Julie. “What we really love is that it feels very contemporary, but also like it’s a garden cottage.”

The bedroom features two large windows on opposing walls and abundant closet and storage space and the bathroom includes a large walk-in shower and a washer and dryer. Because Julie’s mom is a big cook, the family selected a fully equipped kitchen with a full-size built-in refrigerator, four-burner induction stovetop, concealed range hood, and integrated wall oven.

A Building Movement

Managing both projects from start to finish, Bertoni and Type Five design principal Ian Miley adhered to the relatively modest budgets they first outlined for their clients—no small feat given the vagaries of the industry and the pricy market.

“Obviously in the Bay area, there’s a different baseline cost for construction than elsewhere,” says Bertoni.

For larger projects in the area, Type Five builds at a rate of around $500 per square foot, considerably less than the $800-per-square-foot average for local home sales. “And we generally encourage clients to think bigger, when possible, simply because foundations and things like that are where costs add up,” Bertoni says.

On yet a larger scale, budgets aside, Bertoni says the company tries to help clients balance their attachment to a backyard with the idea of creating housing.

“We hope they see the space as a possibility for a home, rather than a ‘tiny house,’” he says. “And we’re definitely seeing more people move past the nuclear family concept of a single-family suburban home with a lawn and white picket fence…and reframe the picture toward something more dense, more social, and more sustainable.”

The two new ADUs are among some 700 others built in Berkeley since the state relaxed permitting restrictions in 2016.

More Budget Breakdown stories:

An LA Garage Is Transformed Into a Vaulted ADU for $230K

A Family Builds a Tiny ADU for $46K—and You Can Purchase the Plans

They Built a Minimalist $437K ADU—to Live and Work Out of Themselves

Project Credits:

Architect of Record: Type Five / @typefivehomes

Builder/General Contractor: Type Five

Structural Engineer: Verdant Engineering

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Budget Breakdown: Here’s What It Cost to Build Two ADUs on the Same Bay Area Block