Mid-Century Modern Expansion

Mid-Century Modern Expansion

Transitional Project | Oakland, California
Nestled among the California Redwoods with stunning sightlines of San Francisco Bay, this remodeled mid-century modern home features an accessory dwelling unit (ADU) layered above the garage to give the secluded comfort of a treehouse. Ultra Series windows and doors transform the space with a clean aesthetic and the versatility to offer expansive views of nature's beauty.

Nestled into the heart of Oakland’s Redwood Heights neighborhood, this 1950s single-family home was thoughtfully renovated twice over the last two decades; once to reflect a quintessentially Californian, mid-century modern design and another to expand the living space to allow for future flexibility.

Vintage Structure, Mid-Century Modern Design


After purchasing the low-rise/ranch style home, Tiffin Groff, the homeowner, began an extensive do-it-yourself remodel that adjusted the house’s appearance to reflect a more Modern-Contemporary architectural style. Groff entirely self-managed the main home’s renovation, spanning 10 years and progressing as her budget permitted. Delivering on both modern aesthetic and performance goals, Groff replaced all the original windows and several exterior doors with Ultra Series products from Kolbe Windows & Doors.

Every part of the renovation was done with quality top-of-mind.

“I've always loved the clean, refined lines, the connection to the outside and the great central living areas of a split-level mid-century modern home,” said Groff. “Every part of the renovation was done with quality top-of-mind.”

All of the interior window and door framing was painted in bright white for a clean, neutral palette. Understated, yet versatile, the focus remained on framing the views of the outdoor landscape’s hearty succulents, bird of paradise flowers, and mature Redwoods.


Connected, but Independent


Years after the major renovations were completed, Groff found herself contemplating options that would allow the home to grow with her family’s future needs. Uncertain of how to add flexible living space while retaining the essential style and scale of her home, she contacted Norman Sanchez Architecture who suggested an innovative idea: build an attached, yet separate, accessory dwelling unit (ADU).

An ADU, complete with a kitchen, bathroom and laundry facilities, could be the perfect place for Groff’s son to live after high school. Later in life, she imagined the possibility of moving into the self-sufficient ADU herself and renting out the main home for supplemental income. Alternatively, she could consider renting the ADU to someone who works in the area.


In California cities, such as San Francisco and Oakland, affordable housing is in short supply. To combat this issue, the state has mandated the removal of many of the hurdles that previously restricted construction of ADUs. While many ADUs convert an existing storage or garage space, they also may be built as an expansion to an existing structure or as a stand-alone unit.

As with other new construction and alteration plans, San Francisco’s Residential Design Guidelines help ADUs to maintain appropriate architectural expression within and between neighborhoods. The city’s planning department’s website elaborated:

“In order to maintain the visual interest of a neighborhood, it is important that the design of new buildings and renovations to existing buildings be compatible with nearby buildings. A single building out of context with its surroundings can be disruptive to the neighborhood character and, if repeated often enough, to the image of the City as a whole.
The Residential Design Guidelines articulate expectations regarding the character of the built environment and are intended to promote design that will protect neighborhood character, enhancing the attractiveness and quality of life in the City. The Guidelines address basic principles of urban design that will result in residential development that maintains cohesive neighborhood identity, preserve historic resources, and enhances the unique setting and character of the City and its residential neighborhoods. The Guidelines also suggest opportunities for residential designs to further San Francisco’s goal of environmental sustainability.”

The views were a major motivating factor. [ . . .] The house sits on a hillside lot and, on a clear day, you get a wonderful view of San Francisco Bay.”


Treehouse with Bay Views


“The overall design was in my head for a long time. Norman helped me bring it to life, positioning it to layer into the main house nicely and capture just the right bay views,” said Groff.

“The views were a major motivating factor,” Sanchez emphasized. “One of the first things we did was to climb up on the garage roof to see how we could take advantage of them. The house sits on a hillside lot and, on a clear day, you get a wonderful view of San Francisco Bay.”

The architectural team took photos from the rooftop and incorporated them into visual mock-ups of the finished space. Along with gazing out to the Bay, the ADU’s windows are positioned to optimize natural elements – the Oakland Hills, the Redwood treetops and the California skies. “We wanted it to feel a bit like a treehouse,” said Sanchez.


Groff and Sanchez turned again to Kolbe Windows & Doors. Sanchez noted, “First of all, they had been used by the homeowner in her previous remodel, so they provided a perfect match. In addition, they provided the shapes and sizes we were after to allow us to take advantage of the views and achieve the more contemporary aesthetic.”

We wanted it to feel a bit like a treehouse.

Continuing the architectural rhythm of the house, divided lite patterns adorn the ADU’s corner windows – the signature design feature. Inspired by the home’s main bedroom windows, the ADU window configurations are consistent with the bedroom, but in much larger sizes. On an even grander scale and view, clerestory windows span across the ADU’s corner windows, with divided lites on the yard-facing side.


Because of the ADU’s sloped ceiling, the clerestory unit facing the street needed to be triangular to follow the roof line. “We were really happy that Kolbe was able to craft the triangular window ‘slice’ to stretch the full width we wanted with a sharp acute angle. I was impressed at how tight they were able to get the glazing, maximizing the viewing area all the way to the corner,” marveled Sanchez.

We were really happy that Kolbe was able to craft the triangular window ‘slice’ to stretch the full width we wanted with a sharp acute angle.

Next-Level Value


Much to her surprise, soon after construction of the ADU was completed, a dream opportunity presented itself across town. Groff decided to put her beloved 2,394-square-foot, four-bedroom, three-bath home with fully permitted ADU on the market.

Working with Jines Real Estate Group, the property was listed at $1,095,000. Within eight days, there were 39 qualified offers exceeding the asking price. In addition to being a beautiful home in a desirable neighborhood, the ADU definitely helped generate additional interest and investment from prospective buyers. The Oakland property sold for $2,400,000 – more than double the listed price.

Jines Real Estate Group’s lead agent, Nathan Jines explained, “The prospective buyers appreciated the personal, thoughtful and significant investment that Tiffin made in the renovation and the ADU expansion.” Jines observed, “With the pandemic, more people are considering where it is they want to live and work. Those who are able to, are primarily choosing to work from home. Many who looked at the ADU and the layout of the house, saw an amazing space that could fit their work-from-home needs, while being flexible for future changes as either a connected or separated studio.”
Sanchez concluded, “ADUs are a tool to provide affordable housing where nothing else may be available in that neighborhood, while increasing the value of a homeowner’s home. It’s a win-win.”