Bruce Johnston adores his residence in Berkeley, California—a Modernist masterpiece designed by architect William Wurster that he has possessed since 1977. As a retired physician and art enthusiast, Johnston joyfully cared for the four-bedroom, 2,929-square-foot dwelling along with the plants and flowers spread across its sloping ⅓-acre property over many years.
As I reached my mid-70s, I genuinely didn’t feel like doing that anymore,” stated Johnston, now 83. “Yet, I considered, ‘What options do I have?’ I adore the community—and leaving this home wasn’t an option since I’ve been living here for such a long time.
Therefore, he opted to relocate uphill.
Perched approximately 60 feet higher than his previous home, Johnston’s new abode isn’t exactly a traditional house; instead, it’s an 849-square-foot accessory dwelling unit—commonly known as an ADU. Nestled within the hillside and built upon a concrete slab foundation, this compact retreat features a floating roof held up by earthquake-resistant steel pillars. Designed by architect Matthew Peek, the structure was finished in 2022 at a price tag of around $1.2 million. The interior feels like a spacious treehouse thanks to its lofty sloped ceilings and clerestory windows that showcase panoramic vistas of the surrounding hills and open skies.
The moment I saw the house rising out of the earth, I became incredibly excited—a blend of awe and incredulity at the fact that this would be my new home,” shared Johnston, who lives in the ADU with his spouse, Tom Noll, aged 65, along with over 200 pieces from their art collection. “It feels like I’m residing in someone else’s luxurious rooftop apartment.”
The newest trend in luxurious homes doesn’t involve features such as a cold-plunge pool, a wine cellar, or a personal spa area. Instead, it’s all about adding a small cottage that enhances your main residence. Think of something similar to the Petit Triancon at Versailles where Marie Antoinette sought refuge—an elegantly compact yet refined abode separate from your primary dwelling, providing an escape from the burdensome tasks associated with owning a large property, including constant maintenance and hosting visitors over weekends.
Many homeowners opt to construct additional living spaces for various pragmatic purposes; these can serve as accommodations for elderly family members or grown children, or they may be rented out for extra income. However, others are planning these additions solely for their own benefit.
Many individuals informed me that despite renting out their accessory dwelling units (ADUs), they planned to incorporate upscale finishing touches,” stated Sheri Koones, author of twelve home design books emphasizing energy efficiency and sustainability. Her most recent publication, “ADUs: The Ideal Housing Solution,” released in March, emerged due to significant public interest. She mentioned, “Whenever I gave talks at libraries, attendees exclusively wished to discuss ADUs.”
An ADU should not be mistaken for a tiny house, which is a movable domicile placed on a platform and could feature elements such as a composting toilet along with various unconventional off-the-grid solutions. Although some tiny houses can indeed be small—in one example from Koons’ book an A-frame ADU spans only 350 square feet—an accessory dwelling unit adheres to building codes and sits firmly on a stable base. It includes designated areas for both living and sleeping, comes equipped with a full plumbing system including a bathroom and kitchen, and often has amenities like a washing machine and dryer.
It isn’t just a pool house,” Koones stated. “It’s meant to be a space where people can truly reside.
The trend of Accessory Dwelling Units (ADUs) began on the West Coast and is still gaining momentum there. To facilitate this, states such as California, Oregon, and Washington have simplified procedures for adding secondary living spaces by eliminating hurdles like compulsory review stages and demands for separate parking areas or garages. In metropolitan areas like Seattle and San Francisco, which face a shortage of available residences, ADUs are viewed as an economical solution to increase housing options without promoting further city expansion.
Despite limited national data on accessory dwelling unit (ADU) construction, California homeowners filed more than 31,000 ADU permit applications last year, up significantly from around 7,000 in 2018, reports the California Department of Housing and Community Development. An examination conducted by John Burns Real Estate Consulting in 2023 revealed that this pattern is moving eastwards, with urban areas like Denver and Miami implementing supportive regulations for ADUs.
In Berkeley, every residential plot that already features a home qualifies for an ADU. Even though homeowners planning to construct an ADU have to inform their neighbors, they do not need the neighbors’ approval.
With an area of 849 square feet, Johnston and Noll’s accessory dwelling unit (ADU) falls slightly short of the largest permissible size in Berkeley for a single-bedroom residence; however, this limitation is offset by an additional 1,300 square feet of exterior space provided through a patio and observation deck. The kitchen transitions into the living area via a flat quartzite counter, while a standalone fireplace delineates the boundary between the living room and the bedroom.
The high-placed windows admit indirect northwestern light, which is kind to the artworks and textiles. Ample eaves extending from the pitched roof provide shady spots and help maintain a cooler interior during summertime. The cabinets in the kitchen and bathroom, bespoke creations made in Italy, boast integrated handles and concealed hinges, offering a seamless appearance.
The Wurster house is currently inhabited by Johnston’s daughter, Katherine Johnston, a 49-year-old pediatrician, who relocated there with her partner about a year ago. (“I told him, ‘Do you want the house? You’re bound to have it eventually,'” her father remembered). The younger Johnston mentioned that her dad’s new residence is “a masterpiece,” adding that they haven’t had issues with privacy due to strategically placed greenery. She explained, “We cannot see into their space, nor can they peek into ours.”
The same can’t be said about life inside Johnston and Noll’s ADU. The open-plan design doesn’t afford much privacy. Soon after they moved in, the couple applied for a permit to build a second accessory unit directly behind it: a 120-square-foot library with a 10-foot ceiling, also designed by Peek, which was completed last year at a total cost of about $76,000. Although Johnston and Noll envisioned the library as an escape hatch—from one another—they usually spend time there together, reading or listening to music.
Leesa Wright, aged 58, who works as a biologist, shares a 1906 Craftsman home measuring just 940 square feet with her spouse, Ben McAllister, 52, in Seattle’s Ballard district. To accommodate visitors and potentially generate additional revenue through rental, they opted to construct a small dwelling within their garden.
Prentis Hale and Rebecca Marsh from SHED Architecture & Design created a 775-square-foot DADU—a term favored in Seattle referring to a detached accessory dwelling unit—positioned roughly 12 feet behind the Craftsman-style home. The structure features metal cladding and boasts double-height ceilings along with a row of four skylights that allow abundant daylight into the space. Upon completion in 2018, which came at an approximate expense of $300,000, Wright and McAllister grew fond of their small abode, affectionately naming it the Alley Cat due to its lopsided, compact appearance.
“We initially believed we would be living in the front house, but then we ultimately stepped into this one,” Wright stated.
The ample ceiling height lends an air of openness, and the secluded position of the DADU ensures privacy. Wright enjoys listening to the patter of Seattle rain against its metallic roofing and appreciates the comfortable heat provided by the radiant concrete floor slabs. The highlight for her is undoubtedly the bathroom, equipped with both a wet-room style shower and a sizable bathtub perfect for relaxation post-gardening activities. “Since this serves as my sole restroom,” she explained, “I made sure to include premium tiles, top-tier fixtures, and excellent windows.”
The pair reversed their plans and settled into their DADU instead. Whenever visitors come over, they use the Craftsman, which mainly functions as an office for McAllister, the director of engineering at an environmental commodities firm.
Lindal Cedar Homes, known for crafting high-end prefab houses along with supplying their construction components, has experienced an increase in orders of their ADU post-and-beam kits over the past ten years, as mentioned by the company’s marketing director, Josefin Kannin. “An increasing number of municipalities are now permitting residents to construct such units,” she noted.
Hy Conrad, an author known for both mysteries and TV production with works like “Monk,” divides his time between two residences—one being a three-bedroom house in Key West, Florida, and another being a sprawling 1910 stone hunting lodge located near the Massachusetts-Vermont boundary line. He shares this second residence with his partner, Jeff Johnson. In 2015, they chose to develop a secluded space atop their Vermont land specifically designed as a quiet workspace for Hy, far removed from the bustling presence of their energetic schnauzers.
I enjoy complete privacy,” stated Conrad, who is 74 years old. “I follow routines closely and don’t engage in any hobbies, so taking time to write fills that void for me.
Collaborating with Lindal Cedar Homes, the pair invested approximately $425,000 to create two 275-square-foot cottages linked by a patio. These structures divide the typical amenities of an accessory dwelling unit into separate spaces. One cottage offers a tranquil bedroom, a bathroom, and a writing desk positioned next to a full-height window that frames views of the forest canopy and surrounding mountains—an ideal setting for composing. Below this space, slightly angled, lies another cottage featuring a vivid red kitchen and a snug living area intended more for relaxation than work.
There’s too great an allure when your kitchen is situated so close by. For instance, ‘I’ll brew some coffee’ or ‘I’ll grab a bite,’” explained Johnson, aged 72, formerly in advertising, who currently dedicates significant effort to the Williamstown Theater Festival as a long-standing board member. Here, he justified the separation for this very reason.
Following the addition of an office to their primary residence in 2019, the couple chose to let visiting Williamstown playwrights use their cottages during the summertime. “Among playwrights, there’s a saying—you must stay at these cottages when you’re in town,” Conrad mentioned, noting that both Tony Award and Pulitzer Prize laureates were among their visitors. “This has turned into quite a mark of prestige.”
Not surprisingly, numerous people are hesitant about leaving.
We’ve had playwrights come in on a Sunday and do their grocery shopping, after which we won’t spot them leaving these two cottages all week,” Johnson stated. “I really hope they venture out and take walks in the woods.
