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 theyâ€™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 Julieâ€™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 otherâ€”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 Chuckâ€™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 Berkeleyâ€™s median home sale price at around $1.4 million, the new neighborhood was a big change, too.

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

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 Julie says â€œwas never used much, and was literally falling apart.â€

$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 budgetâ€”as would an addition to the house itself. One suggested looking at prefab ADUsâ€”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 â€œsite-build modularâ€ design and construction system that lets clients participate in their projects through a streamlined process with a transparent budget.

â€œAs both architect and general contractor, weâ€™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,â€ 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 homeâ€™s rooftop photovoltaic panels to help minimize costs. In fact, the ADUâ€™s total cost of $196,270 was less than the coupleâ€™s bathroom remodelâ€”and the unit regularly proves its utility.

â€œI use it as an art studio when Iâ€™m working on a project, and with the Murphy bed, itâ€™s really easy to set up my table and get to work,â€ says Susan. â€œOur 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.â€

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.

â€œEven compared to the old garage, it feels so much bigger with these big windows,â€ says Susan.

Julie and Joeâ€™s One-Bedroom

The windows are actually what convinced Julie and Joe, who were themselves considering cheaper prefab options, to contact Type Five. â€œWe 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,â€ says Julie.

Their project was the product of a long-planned partnership with Julieâ€™s parents. â€œWe bought the property, and they would pay for the ADU, which made it possible,â€ says Julie. â€œBut there would be joint decisions.â€

The unit had to match the house and blend with the neighborhood, and they wanted it to have high ceilings and large windows. â€œBut we thought the windows shouldnâ€™t look onto the main house, so that the unit would feel more separate,â€ 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.

â€œMy mom really leaned into it,â€ says Julie. â€œShe wanted French doors for the front door, which was a game-changer in terms of making it feel like youâ€™re really in the garden.â€

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

â€œMy parents actually donâ€™t like modern style at all, and at first, they were like â€˜why are there no baseboards?â€™ but then they spent time in it and saw how it made sense for the small unit,â€ says Julie. â€œWhat we really love is that it feels very contemporary, but also like itâ€™s a garden cottage.â€

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 Julieâ€™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 clientsâ€”no small feat given the vagaries of the industry and the pricy market.

â€œObviously in the Bay area, thereâ€™s a different baseline cost for construction than elsewhere,â€ 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. â€œAnd we generally encourage clients to think bigger, when possible, simply because foundations and things like that are where costs add up,â€ 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.

â€œWe hope they see the space as a possibility for a home, rather than a â€˜tiny house,â€™â€ he says. â€œAnd weâ€™re definitely seeing more people move past the nuclear family concept of a single-family suburban home with a lawn and white picket fenceâ€¦and reframe the picture toward something more dense, more social, and more sustainable.â€

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 $46Kâ€”and You Can Purchase the Plans

They Built a Minimalist $437K ADUâ€”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: Hereâ€™s What It Cost to Build Two ADUs on the Same Bay Area Block