Hairpin House

Boston-based architecture firm Studio J.Jih and San Francisco-based studio Figure have transformed a four-story, 15-foot wide historic brick rowhouse in Boston’s South End. Aptly named Hairpin House, the project takes the tight, unpredictable, and ultimately poetic switchback turns of a mountain road as inspiration for the overall renovation—and, in particular, a new unraveling central stair.

The homeowner, a Boston native, engaged the design team to update the rowhouse and expand its usable space. The principal challenge was to reorganize the floorplan; in particular, to remove and re-envision a hefty existing stairwell that consumed an entire third of the small home, bifurcating it down the middle. “It was incredibly inefficient in terms of its barbell plan—an entire third of the footprint was eliminated by this stair,” says Jih.

Through extensive experimentation and fine-tuned calibrations that accommodated Boston’s strict building code, the architects envisioned a more efficient stair that would dynamically reorganize the space and establish its material palette. The result is a custom-built white oak staircase that unspools diagonally through the home, increasing usable square footage by over twenty percent. Significantly, its angled path jettisons the uniformly square rooms of the original floorplan in favor of a more nuanced layout, where primary programs (dining room, living room, primary bedroom) enlarge and supporting programs (foyer, powder room, bathroom) shrink.

“We performed a sort of stair gymnastics where each flight was distinct from the others, because of its necessary interface with the unique programmatic and circulatory conditions on each floor,” says James Leng, partner at Figure. “Like how a mountain road derives its form from the slope it rests on, this central stair was truly shaped contingently through the pressures of its interior context.”

Due its geometric complexity and constraints related to the tight building envelope, the new stair was fabricated off site in one-story segments then set into place on site. Hand-crafted from white oak, it consists of winding stairs, tightly arranged balusters, and a sinuous, rounded handrail that draws a continuous line down through four levels. “As this hairpin stair cascades obliquely through the four-story brownstone, it carves out a connective forty foot atrium within which this misbehaving element continuously reconfigures itself—from straight treads to winders, from solid to open balusters and back again—producing a sculptural figure and vertiginous space within a highly constrained site,” says Jih.

This elemental, organic object exemplifies the home’s neutral material palette, which is meant to evoke an indeterminate era: contemporary but also appropriate to the time of the rowhouse’s original construction in 1892. Floors throughout are white oak and, in select areas like the ground floor and bathrooms, are a softly mottled french limestone. Walls are a rich lime plaster applied directly to brick, allowing for breathability, moisture diffusion, and textural depth. Other defining volumes—a muscular, monolithic stone kitchen island on the ground floor and faceted fireplace on the first floor—are hewn from singular blocks of travertine.

These subtly textured surfaces are activated by natural light that pours through new, enlarged steel french windows and doors across all levels at the South-facing rear of the house. Each was increased in scale by over 200%, creating a rear facade graced with daylight, views, and which elegantly blends into age-old brick of Boston’s historic architecture. A back patio made of bluestone and designed by Pate Landscape Architecture ties the exterior space to the interior palette, while the garden’s perimeter is powder-coated steel edging and encased by cedar walls.

Says Leng of Hairpin House and the collaboration that drove it: “A great deal of the joy we found in this project was in the process of shaping it from so many dizzying constraints, but it also needs to be said that the project could only have been sculpted from the intensely productive collaboration between our two firms. As an emerging generation of architects seeking alternative approaches to authorship, it was so incredibly gratifying to develop a process in which we were able to arrive at something more beautiful because we worked on it together.”