Case Study: Oak & Alder by Hybrid

New houses are never just about space, or even objects of art on the street. They influence the aesthetic and socioeconomic fabric of their neighborhood, not just in the present but for years to come. Developers, in particular, need to acknowledge the sociological effects of the homes they build. What can they design that is continuous with a community? What does modern living require? And what conditions can make houses affordable to the folks who already live there?

Rob Humble and Alex Herbig mull these questions when they design homes on Seattle’s infill lots. Oak & Alder is one of several compact projects their architecture and development firm Hybrid has built since Seattle passed a rezoning overlay, known as urban villages, to revitalize the city and curb suburban sprawl by concentrating multifamily housing in hubs close to public transit and other amenities.

 In this case, Rob, principal of Hybrid Development and Hybrid Architecture, lives in this Central District neighborhood and landed the project through a friend who runs a local brewpub. The owner had lived in the house for about 15 years before the area was rezoned. Seeking to move, he decided to subdivide the lot before selling his house, and asked Hybrid for help. 

“His corner lot had an undeveloped side yard,” says Alex, the firm’s design director. “We helped him subdivide it and then bought it from him. He retained ownership of the existing house and subsequently sold that.”

The challenge was to build a habitable two-unit structure with three parking spots on the remnant 2,024-square-foot lot. To establish a viable footprint, the firm engaged the city’s streamlined design review process, receiving permission to adjust the requirements for setbacks and façade length. Their massing studies resulted in perpendicular 20-by-20-foot cubes with a 5-foot “gasket” between them. The larger front unit is 1,596 square feet, while the back unit has 1,292 square feet—both stacked three stories high.

The twins’ taut, COR-TEN-clad walls and roof are a modern interpretation of the buildings around them. “The neighbors’ roofs pitch away from the street, similar to ours, and they also have four or five steps to a recessed front porch—things people associate with home; we did the same thing,” Rob says. “The siding pays attention to what’s happening on the other side of the street, where a 100-year-old brick high school building is almost identical in color to our COR-TEN.”

Stack Effect

A hallmark of Hybrid’s multifamily buildings is the inclusion of flexible spaces, some of them rental-ready to help buyers afford a mortgage. For the developers, it is a way to address the rising costs of home ownership, especially in pricey cities like Seattle. Each unit was intended to have a ground-floor studio with a kitchenette; however, during construction the project caught the eye of a family of four moving from Copenhagen. They pre-purchased the smaller unit sight unseen and requested two bedrooms and a bath for their young children on the ground level. The owner of the larger unit rents the bottom floor to a friend.

The other designated flex space is a loft with venting skylights. “We recognize that working from home is a huge thing, and not everyone wants to work in a spare bedroom,” Rob says. “So we created a loft in the gabled volume that looks down to the space below.” In the smaller unit, it serves as an office, while the owner of the larger unit uses it as a music studio. Tucked into the roof volume, those lofts also substitute for the lack of a roof deck, a consequence of building with pitched roofs. “Having a roof deck is nice on a small lot, but in summer they can be hot and windy and exposed, and we saw the lofts as adding more value on a daily basis,” Rob says. “We ganged the four biggest operable skylights we could find in the pitch of the roof to create a solarium, which is nice in the winter.”

If a cube is the most cost-efficient volume to build and operate, the interiors are also clean, durable, and appealing. Above the ground-floor rooms, the entry level contains a bedroom, two baths, and storage, while the living level and loft at the top of the house capture light, breezes, and city views. Baths, closets, and stairways are concentrated in the gasket space, which has a second-level deck belonging to the larger unit. 

“We included decent-sized closets and storage on every level, including under the stairs,” Rob says. A neutral material palette of whites with gray and wood accents keeps the interiors bright in this rainy climate. The front unit has carbonized bamboo floors and a kitchen fitted with white countertops and fir cabinets in keeping with the loft’s exposed structural fir, while the back unit’s owners chose colored kitchen cabinets that harmonize with their collection of furniture and art. 

Outside, a 6-foot rough-sawn, stained tongue-in-groove cedar fence continues the houses’ 6-foot cedar base to the property line, shielding the parking from the street. “We can’t build to the property line here, and you see many houses set in the middle of the lot with cheap cedar fencing that butts into it,” Rob says. “This was a way to extend the boundaries of our buildable area out to the property line.”

On a Continuum

With a sales price of $1 million, it’s hard to say these units are affordable except in the context of other new construction, the partners admit. “We are 20 percent below the cost of median new construction in the city, and a big part of what drives that is the small, efficient size,” Alex says. “We feel like this project doesn’t sacrifice bedroom counts but includes them in the most efficient package possible.”

Of course, operating costs are also part of the affordability equation. Spray foam insulation, heat pump water heating and indoor conditioning, and energy recovery ventilators boost utility performance, as does passive heating and cooling through large windows and operable skylights at the top of the house. The houses are wired for future solar panels, each parking spot has an EV charging station, and there is on-site bike parking, as required.

As it did on this project, the firm tries to partner with existing property owners to develop their lots sensitively rather than create new construction that will alienate people living in the neighborhood. And the architects see Oak & Alder as a sculptural representation of what a historic house would be in Seattle, with materials that will age gracefully and imbue a sense of permanence. “We try to recognize that development is happening in the middle of a neighborhood’s history,” Rob says. “It’s not, ‘I’m a new thing’ that in 10 years can be lost in the fabric of redevelopment. Our homes are intended to be around for the next 100 years and should reflect on the last 100 years.”

Oak & Alder


Project Credits

Architect: Robert Humble; Mike Ennen, Hybrid, Seattle

Builder: Andrew Fawcett, Hybrid Assembly, Seattle

Interior designer: Robert Humble and Alex Herbig, Hybrid

Developer: Robert Humble and Alex Herbig, Hybrid Development

Landscape Architect: Glenn Takagi, Seattle

Engineering: Sazei Design Group, Kirkland, Washington

Project size: Front unit, 1,596 square feet; rear unit, 1,292 square feet

Site size: 0.046 acre

Construction cost: $390 per square foot

Photography: Rafael Soldi

Key Products

Cabinetry: Abodian Cabinet Company

Cabinetry hardware: Berenson Bravo Pulls

Cladding: COR-TEN Box Rib Metal

Cooktop/range: Frigidaire

Countertops: Quartz, Richlite

Dishwasher: Beko

Door hardware: Kwikset

Faucets: Delta, Vigo

Lighting: WAC

Refrigerator: Summit

Sinks: Elkay, Vigo

Skylights: VELUX

Toilets: Signature Hardware