Seattle recently jumped into the rankings of the 10 densest big cities in America—a phenomenon that makes Alloy Design Group’s design for 2800 West Boston Street and its neighbor an object lesson in how to do what’s likely to become more common in the future.

"Density is really important,” Alloy principal Mark Haizlip says, noting that maximizing land use through infill is an important development tool to create vibrant urban environments. The site’s previous single-family house was spread over two lots—an unusual configuration for the neighborhood, which consists of closely bunched single-family homes. Its form might best be described as “bungalowy,” Haizlip says. “It was kind of nondescript with a lot of roof.”

The first order of business was to split the property into two lots and develop two individual residences that better fit the neighborhood’s predominant scale, even as their modern, boxy forms deviate from the more common pitched-roof Craftsman style. Since the lot size was typical for the neighborhood, there weren’t many difficulties with permitting or construction, but the team did have to submit a lot boundary adjustment to the city since the plot was originally split into two unequal parcels. But as far as paperwork goes, the process was simple—an application showing the previous lot configuration and the proposed one was taken care of by a three-sheet submittal by the surveyor.

Located near the top of a hill, the new, 3,134-square-foot, four-bedroom home has two primary living levels stacked above a ground-floor garage, all topped by an expansive roof deck. A guest suite and family room are located behind the two-car garage on the first floor, which was depressed into the side of the hill to allow for maximum ceiling heights on the levels above. Concrete retaining walls provide a monumental stair that defines the corner of the block, a nice touch that sets up an open series of formal living spaces on the second and third floors.

The small entry area, which is open to the full height of the house, welcomes visitors to the open-plan public spaces on the second floor of the 24-foot-wide home. Collapsible glass doors open the space to a small balcony, which makes maximum use of a small exterior space by framing views of Puget Sound in the near distance.

A master bedroom suite occupies the front of the house on the third floor with two additional bedrooms, a laundry room, and a bath toward the rear. The stair continues up to the roof deck, which has panoramic views of downtown.

Material contrasts break down the massing of the house to provide a sense of scale. On the exterior, horizontal cedar siding denotes circulation spaces, with white and black fiber cement on the majority of the other surfaces. White panels clad the living spaces, and black panels clad the stairs.

Haizlip developed the design with an eye toward function, emphasizing open living spaces that maximize views and maintain privacy. The aesthetic may be unusual in the Magnolia neighborhood, but the designer is comfortable, if some find the look jarring. “The scale is similar,” Haizlip says. “It looks different in large part because of the flat roof.” He maintains that the house doesn’t have a particular style, preferring simply to say: “It’s modern."