Vintage row houses, those quintessentially Washington dwellings, can hide all manner of surprises. Case in point: a circa-1900 dwelling near Dupont Circle whose classic, red-brick façade conceals streamlined interiors ingeniously reimagined by modernist architect Robert Gurney.

The homeowner, a longtime client who works in finance, first considered the four-story, 2,332-square-foot house as an investment opportunity. However, she changed her mind on seeing it. “I grew up in New York,” she says, “so it was always sort of a fantasy to own a brownstone. I figure this is the closest I’m going to get to that in DC!” But as a fan of modern architecture, her fantasy brownstone veered contemporary on the inside. “I called Bob as I was walking out the door after touring the house,” she recalls, “and said ‘I have a project for you.’”

When the time came, Gurney enlisted a team that included colleague Kara McHone, designer Therese Baron Gurney (his wife and frequent collaborator) and builder Peterson+Collins. They had their work cut out for them, as the building was dilapidated—to say the least. “It had been a sort of rooming house, with a kitchen on each floor,” recounts the architect.

Working with McHone, he devised a plan that would gut the dingy interior spaces and create a 300-square-foot, glassed-in addition at the back of the basement and ground floor (zoning prohibited extending the upper floors). The main level became a single, open-plan room with the front living area flowing back to the kitchen and the dining area in the addition at the rear. The second floor encompasses the primary suite, which boasts a back patio, and the third holds two spare bedrooms. The basement includes a playroom and a home office.

In the revamped layout, the main level feels more spacious than its 20-foot width would indicate. “It’s a nice homage to the original space,” comments principal Ted Peterson, who spearheaded construction. “The rear addition was critical to the project’s success, as it elongates the room and makes it feel wider.”

The front door opens to an airy, floating stair that was relocated to its current spot along the wall. “The whole concept is organized around the stairwell, which cuts through the ceiling to a skylight at the top,” Gurney explains. “We came up with this system of a welded-wire fabric wall instead of a glass railing; reclaimed-white oak slats are layered over it on the main floor to add more texture.”

Beyond the stair, a functional core opposite the sleek kitchen holds a powder room and pantry; it extends to the second and third floors, where it houses the laundry room and a bathroom respectively. Also part of this core: an elevator that runs from the basement to the third floor, enabling the owner to age in place.

With visiting grandchildren in mind, robust, durable materials were specified—a mandate that inspired the architects’ palette of reclaimed-white oak surfaces, hot-rolled-steel accents, Italian stone-look porcelain flooring and dark-stained white oak on cabinets and upstairs walls. “I wanted a sophisticated look with some different materials,” notes the client, “and nothing too delicate.”

Those materials create continuity among spaces and delineate rooms in lieu of drywall—particularly the reclaimed white oak, which appears on floors, stair treads, walls and built-ins throughout the house. “With the home’s width, I thought all the wood might be overwhelming, but it makes the walls that much more special,” observes Peterson. “The door hinges are concealed and all the wood is matched. That kind of detail defines Bob’s projects.” To address the wood’s natural expansion and contraction, Peterson’s team fabricated the walls with quarter-inch reveals between panels that allow for movement; these echo the reveals typically found in modern architectural spaces—including this home—where moldings are eschewed.

Gurney and McHone also orchestrated finishes in the kitchen and bathrooms. The former combines custom, dark-stained oak cabinetry by Affinity Woodworking with terrazzo countertops; the nearby powder room sports the same surface. Frosted-glass walls define the minimalist primary bath on the second floor.

The cellar floor was lowered 16 inches to provide additional ceiling height and covered in polished concrete. A home office, tucked into the rear addition, is brightened by a spacious light-well-cum-patio visible through a wall of windows and accessible via a glass door. A quartet of young grandchildren enjoys time in the adjacent playroom.

Therese Baron Gurney’s interiors “support and blend the furnishings with the finishes,” she explains, adding that her involvement with the client carried over from a prior project. “We reconfigured many items from her previous house, adding new pieces to make them work specifically within the new environment.”

The owner is thrilled with her vintage row house and its elegant yet livable modern interiors. “I love it here, I love how it feels,” she enthuses. “It really works perfectly for me.”