The Sonoma residence is a small, minimalist home created in close collaboration between the Architect in Minnesota, and the Owner, Apple’s director of architecture in San Francisco.
The project is composed of two minimalist open-sided boxes set on concrete plinths nestled on the edge of gnarled oaks to the south and an expansive view of the valley to the north. The solid sides of the tubes were designed to focus the views in the two directions only, provide privacy from each other, and establish a strong presence comparable to the landscape.
The two dwellings were designated as a Secondary Dwelling Unit and a Guest Unit, which had maximum sizes of 640 and 400 sf respectively, while leaving open the possibility for a future (larger) Primary Dwelling (which is not planned). The benefit of the size restrictions were that the dwellings could be tucked into the narrow zone between the coastal oaks and the grade drop off to the valley and become part of the landscape in an intimate way.
The house was fabricated off site in three modules that arrived 90% complete. Both structures feature steel frames, 9 ft. tall sliding glass walls that are set into custom corrugated weathering steel boxes, and ipe wrapped interiors with oiled oak cabinetry. Both the steel and the ipe will weather over time to more fully integrate with the landscape.
The 16 ft. x 40 ft., 640 SF primary structure features a whitewashed oak bed box in the middle of the volume, leaving an open kitchen-dining-living room on one side, and a toilet and shower on the other. For shipping logistics, the 10 ft. x 40 ft. porch was bolted on-site, and cantilevers dramatically over the valley.
The accompanying 330 SF guest house is an abridged version of the larger module. It is sited only 8 feet from the primary structure, but raised 30” to respond to the grade, the trees, maintain a sense of the its own space, and play with the scale of the boxes. The Owner specifically did not want a lot of storage in the house, but that which is there is hidden into the kitchen, the floor and thick walls of the bed box, the single wardrobe, and the basements.
Contextual Information
The site is nestled beneath native, coastal oaks overlooking Sonoma Mountain, a valley rich with vineyards, a state and a regional park, and the town of Santa Rosa. The decoration - if it can be called that - are the views themselves.
The board-formed concrete plinths form the base and the entry patios, and separate and connect the dwellings to the site while to playing with the proportions of the boxes, grade, and dramatic trees. The lightweight stair and the railings on the plinths are galvanized steel to match the concrete. The railing that is within the main structure is weathering steel to complement the oxidized steel box.
Resiliency Features
Together, the two structures offer a kitchen, living, dining room, two bedrooms and two bathrooms, and occupy 970 SF. Inspired by the notion that “the greenest square foot is the one you don’t build,” the house is a compact, economic design that celebrates the luxury of less, and makes the most out of a potentially restrictive zoning envelope.
The Sonoma project’s oxidized steel exterior rainscreens involve no maintenance. Water-saving is dictated by strict water-use regulations for the area, and include buried grey water tanks down the grade.
The structures are sited within the shade of long-established oaks which shade the southern glass. The shell uses spray foam insulation to maintain a tight envelope. The glass is specially coated to allow high levels of visibility while eliminating solar heat gain. Motorized shades and window screens allow owners to maximize or minimize sunlight.
Because of the temperate climate, having complete glass walls on both the view and the sun side of the house made sense. Daily breezes that rose either up the hill or down cool the house off easily with the doors open.
The Sonoma Residence sits in an ideal, temperate climate. Overall energy use is low as the small structures can operate on heat pump mini split units hung in the basements with minimal draw. Natural daylight supplemented with all LED spots and strips reduce lighting loads as well.
The sustainable impact of the house derives more from its approach to the program size rather than specific active or passive techniques. Innovative Design and/or Construction Features
Describe innovative design and/or construction features of your project.
Less is more (work).
The design of the Sonoma residence was an exercise in logistics and efficiency paired with a design that maximized that process. To maintain high levels of quality, with cost controls and enable the Owner to fit the build into his restricted schedule, it was built in Oregon and shipped to its Santa Rosa, CA site 90% complete.
Custom steel fabrications were shipped from Minnesota by the Architect to help maintain control and design quality in the finished work. Because the house was prefabricated off-site, dimensional tolerances were critical in fitting in the program within the limitations of modular shipping constraints. The house’s openness belies its small size, with floor to ceiling glass on the view sides evaporating the membrane between house and site.
Much of the detailing work arose from the tight space from which the modules were designed and the need to efficiently connect up the parts on site. Dealing with the pragmatics of a slim envelope as well as the cantilevered steel structure were both challenging in this small of scale. Insect screens and privacy / solar shades were designed to pocket within the ceiling cavity.
The porch beam was pre cambered to allow it to span 40’.
The planning stage lasted 9 months and the actual build was completed in 4 months in factory.
The installation took only one day once the trucks and crane arrived onsite. The glass sliding doors were installed in a mud bed that meant that they were most efficiently installed on site.
The cabinet cores are IKEA customized with custom faces made from refinished engineered flooring
