At first appearance, with its modest windows and great expanse of brick, a renovated four-story home dating to the 1920s in the Rock Creek neighborhood of Washington, D.C., looks conservative and polite, like the houses nearby. It does not scream. But in the rear, the house opens up. The southern facade is lined with windows, concealed from passersby and motorists, and the southeast corner is a series of glass boxes that jut out a few inches from the main house. From the top floor, there is a view of the Washington Monument and the great swath of the Mall. The front of the house is discreet; the rear is not. It is nearly transparent.

“The house is hybridized,” says architect Nader Tehrani, who designed the renovation. Principal of the Boston and New York–based firm NADAAA, Tehrani is also dean of the Cooper Union Irwin S. Chanin School of Architecture in New York City. “There are cellular rooms on the north side, which is private,” he says. “The windows are classically organized. On the southern side, there’s a new regime—each window establishes a direct relationship with a room.”

The architect’s renovation also formally demonstrates, with rigor, the distinctions between traditional load-bearing wall construction—expressed on the street-facing brick facade—and modern curtain-wall, open-plan construction, as expressed on the home’s rear expanse of glass. “The house demonstrates both traits,” he says.

The house not only has dual identities; it also has twice as much living space as it did prior to the renovation. Originally comprising 5,000 square feet, it now spans 10,000. Along with the landscaping, most of the work was completed last year.

Recessed Element lights by Tech Lighting provide a minimalist touch." layout="wide" credit="Photo by John Horner" photoUserId="6133436791803105280"/>

The owners of the house, a businessman, his wife, and their three children, asked Tehrani, a family friend, to update and enlarge the home. They wanted to expand their family, have live-in help, and entertain in a more comfortable way.

Doubling the size of the house was simple, the architect said. “This was due to the basement being on the garden level, with excellent light and exposure on the south side, and the attic space being already accessible.” The top and bottom floors could thus be enlarged without expanding the footprint.

To open up the rear facade of the house and make it so transparent, Tehrani removed bricks to allow for larger windows. He then used the same bricks to fill in areas of expansion on the attic-level walls.

Inside, the architect worked extensively with plywood, to exceptional, sensual effect, so that the wood seems just slightly curved, from the stair railing to the panels that accent and line the walls. “I like plywood because it is a raw part of industrial manufacturing today,” the architect says. “It’s generic, and standard. We reveal its edges; we take the conventional and try to do extraordinary things to it.” The subtly curvaceous wood “is not bent,” he notes. “It is routed to produce slightly attenuated figures.”

Organic, undulating forms frame the stairwell that connects the first floor and garden floor. Though they give the appearance of bent plywood, each curved layer of the ribbed corridor was constructed with flat, laminated cutouts, including the rounded hand rail. " layout="" credit="Photo by John Horner" photoUserId="6133436791803105280"/>

He designed a central staircase of slatted-wood panels that unites the upper three floors. The tops of the panels form the railing, which curves slightly. To walk from the first floor to the garden floor, which leads directly to the swimming pool and garden, he inserted a second staircase that is framed by a series of undulating wood panels that increase gradually in size. On the first floor, the staircase is glimpsed through a tiny, curvy, somewhat oval-shaped cutout. Tehrani describes the effect as akin to peeking through an opening into a cave.

Sited along a north-south axis, it’s a house in which no one can get lost: The dazzling light from the exposed southern side of the house is the visual, sensual, ever-changing anchor. When the residence is lit from within, the transparent southern facade reveals the function of every room, each of which has its own single or double aperture.

In Tehrani’s residential designs, doorknobs and drawer handles are sometimes absent. “We absorb the hardware into the architecture,” he says. Some doors have recessed indentations for opening and closing. When hardware does not protrude, the architecture is singularly uncluttered.

A view of the central staircase from the entry-level floor emphasizes vertical, tapering forms, a motif found throughout the home." layout="" credit="Photo by John Horner" photoUserId="6133436791803105280"/>

The main common areas are on the ground floor. The husband’s office is tucked into the east-facing corner, with windows looking out on the garden and the pool; next to his office is a seasonal living room, used in winter, when the family can enjoy the fireplace. (A summer living room is downstairs.) “The couple discovered their needs through the design process,” says Tehrani. “The idea to have two living rooms was not a requirement but a discovery of the difference between summer and winter activities—around the pool versus around the fireplace.”

On the western side of the floor there is a white kitchen next to a casual dining area, and the family room, which is also informal. Much of the furniture throughout the home is midcentury modern, including pieces by Finn Juhl, Hans Wegner, and Alvar Aalto. There are also Italian designs by Antonio Citterio, Rodolfo Dordoni, and Piero Lissoni.

The central staircase, lit by a skylight, climbs to the second floor, where the master suite is on the eastern side and the children’s rooms are on the northern, western, and southern sides.

“The parents didn’t want anything extravagant,” notes Tehrani. “They said, ‘We like our rooms small.’” On the stair landing of that floor is a pentagon-shaped table, called the Pentavola, which the architect designed so that there is one side for each member of the close-knit family. “They eat together, they do homework together,” he explains, all at this communal table.

On the garden level, the wife has an office in the southeast corner, adjacent to the summer living room, with its access to the pool and garden. A dining table for 12 and a catering kitchen with warming drawers, a dumbwaiter, an ice maker, and wine storage are nearby.

What dominates the garden level, however, is a striking piano—the PH Grand, a 1931 creation by legendary Danish designer Poul Henningsen—featuring a metal-framed celluloid top that appears not unlike a windowpane or perhaps the sail of a boat. When someone plays the piano, the motion of the felt hammers is visible. You hear the music, and you see it being made, from the fingers to the hammers. Like the house itself, and the shaping of the plywood throughout, the piano is altogether not ordinary.