From the very inception of Washington, alleys have crisscrossed the city's blocks, invisible passageways etched deep into the urban core. Over the course of generations, they have played host to horse stables, carriage houses, garages, artisans' workshops and slums of such squalor that a 1912 inventory deemed them "evil."

Now, the District's alleys may be the next frontier in the city's red-hot housing market. And across the country, cities including Austin and Denver are also turning to alleys in the hope of tackling unabating crises in housing affordability.

"This is creating new housing opportunities in places that are woven into our neighborhoods and were previously pretty much unavailable to us," said Cheryl Cort, policy director at the Coalition for Smarter Growth. Adding alley-lot dwellings to a neighborhood block, she added, "can substantially increase the housing opportunity on that block . . . and that is a meaningful contribution to the diversity of housing choices and housing type."

Tucked behind block upon block of neat rowhouses in the Capitol Hill neighborhood is an intricate network of alleys. The alleys, which historically served as back entrances or equestrian passageways, and in the city's more recent troubled past as the domain of prostitutes, gangs and drug dealers, are today largely underutilized and underdeveloped. But the city's new zoning code, which went into effect last September after almost a decade in the making, now makes it easier to develop alleys, easing previous restrictions like the minimum width of an alley, height limitations, and its distance to a main street.

One person doing a lot of that developing is Sean Ruppert.

Ruppert, the principal of the development firm OPaL, last month listed his latest completed alley project on the market, on Adolf Cluss Court SE in the Capitol Hill neighborhood: two 2,700-square-foot apartments, built out of a 1920s-era brick garage, for $1.895 million apiece.


Sean Ruppert, principal of developer firm OPaL, outside his newly renovated 1920s three-car garage. D.C.'s alleys may be the next frontier in the city's red-hot housing market. (Keith Lane/For The Washington Post)

Ruppert has done a handful of alley projects in recent years, including the award-winning three-home Naylor Court Stables development in the Shaw neighborhood of Northwest Washington, and has noticed the growing popularity of alley homes among home buyers.

"I think there's more of a willingness to live in alleys," he said. "Now it's seen as a quirky, unique space to live in, especially in a city that is so full of traditional row homes. This is really quite a unique space."

Ruppert is betting on growing demand for alley homes. Just a block and a half away from his Adolf Cluss Court project, he is collaborating with local developer Martin Ditto of Ditto Residential on an alley project that will feature 45 residential units when completed. The project is being billed as "D.C.'s Next Great Alley."

Individual homeowners, too, are increasingly interested in developing alley lots, said Nick Burger, a commissioner with the Advisory Neighborhood Commission on Capitol Hill who has been helping his constituents and other neighborhood residents through the long, complex process of obtaining permission to develop alley lots. In his neighborhood alone, four alleys have been named since last September, all in relation to plans for development, Burger said.

"What we found was that the vast majority of alleys on Capitol Hill . . . didn't have names," he said. "What many of these alley lot owners found was that they couldn't build until they got an address, and they couldn't get an address until the alley had a name."


The exterior of a newly renovated 1920s three-car garage is a visible sign of a new interest in converting old utilitarian buildings into family homes. (Keith Lane/For The Washington Post)

And then there are neighbors to placate.

Gillette Wing, who grew up in the District and now lives in Kingston, N.Y., owns an alley building just five blocks from the Capitol. The former stable used to be her grandmother's, and when she passed away, ownership was transferred to Wing's parents. But the property was left in limbo after Wing's parents divorced, and for years the building was used only for storage, slowly falling into disrepair.

After the new zoning code went into force last year, Wing started thinking about turning the building into a residential space. Because the building didn't fit the exact conditions laid out in the zoning code — for one, the 10-foot-wide alley was less than the required minimum width — Wing had to apply for a special exception, a process that includes input from neighborhood commissions and other D.C. agencies. Initially, some neighbors weren't too pleased.

"Nobody wants construction in their back yard. I understand that," Wing said. "I think there were points when it seemed like, oh, is this going to be so hard and painful?"

Wing ultimately won the support of the neighborhood commission, and a final hearing this week before the Board of Zoning Adjustments also yielded a unanimous vote of approval.

While the rehabilitation of vacant alley buildings into residential homes is not new to the city, the recent flurry of activity involving alleys — both from developers like Ruppert and individuals like Wing — points to a growing public consciousness of all that an alley can hold.

Alley homes, Ruppert said, "are trending, but not trendy." Yet.

The affordable housing crisis afflicting cities nationwide is partly a physics problem: There is only so much space to build on, but an ever-growing population to accommodate. Alley dwellings, experts say, help by creating housing options in existing, underused space.

"You're kind of filling in the cracks and crevices," said Yolanda Cole, the senior principal and owner of Hickok Cole Architects, which is providing architectural services for the 123-unit residential project on Blagden Alley, in the Blagden Alley/Naylor Court Historic District downtown. Construction is expected to begin early next year.

Capitol Hill, the site of many alley buildings, has seen property prices increase by about 30 percent in the past five years, according to the online real estate company Zillow. Alley homes could take some pressure off the housing market, said Cort, of the Coalition for Smarter Growth.

"We think it's great to bring these places back online in order to create more housing opportunities," she said. "A smaller space also costs less to build, so it's naturally less expensive."

Of course, alley homes alone won't solve the housing crunch. High-end homes like Ruppert's Cluss Alley will be out of reach for many, and even non-designer homes may be too expensive for low-income home buyers. But middle-income households are also struggling to find affordable places to live, and alley homes can fill in the "missing middle" of housing, said Lisa Rother, executive director of Urban Land Institute Washington.

"It is not a big deal in and of itself," she said of alley homes. "But I think what's important is we need to use every single way of creating affordability in our toolbox. It's not one-size-fits-all."

Other cities are looking to alleys as a way to increase housing stock.

In Austin, the Alley Flat Initiative has identified a network of vacant and underused alleys in the city's east, and is working to build alley flats in the residential lots facing these alleys. The initiative has built seven such flats and has another 10 in development, according to Nicole Joslin, who heads the program as executive director of the Austin Community Design and Development Center.

And in Denver, the Single Family Plus housing initiative, spearheaded by the city-supported West Denver Renaissance Collaborative, will kick off next spring with the goal of building 250 backyard or alley homes over five years.

Those homes, called accessory dwelling units, are technically different from the alley lot buildings seen in Washington. Instead of a structure on an alley lot unconnected to a street, an ADU is an additional dwelling on a single-family lot, either attached to the main building, say in the basement, or detached as a separate structure at the rear of the property. But while ADUs and alley lot dwellings differ in definition, they serve largely the same purpose: putting free space to use.

"Our goal is to create a pathway to make ADUs accessible to low- and middle-income homeowners," said Renee Martinez-Stone, the collaborative's director. To streamline the process and to reduce building costs, the initiative plans to offer a menu of preapproved ADUs for homeowners to choose from.

And beyond expanding the housing stock, the repurposing of alleys offers a new way to build and engage with the urban environment.

For Rebecca Summer, a PhD candidate in geography at the University of Wisconsin at Madison who has studied alleys in the District, how alleys are regarded in the public's mind offers a clear snapshot of the city. Where alleys used to be treated as breeding grounds for vice, they are now celebrated as edgy and quintessentially urban, she said.

"Now, they're still hidden," Summer said. "But instead of people denigrating them, they're seen as cool spaces."