Welcome back to The Architect's City, a monthly series inviting an emerging architect to reimagine an existing structure in his or her city, submitting a speculative proposal for Curbed readers. This month, we visit Baltimore.

Vacant and abandoned homes dot Baltimore's landscape, and they "do not bode well for a neighborhood," says Jim Shetler of Baltimore-based Trace Architects. "There are more opportunities for mischief and there's increased flight. As soon as blocks start being vacated, people want to get out of there." The U.S. Census Bureau counts 48,600 vacant buildings in the city; of those, the city itself estimates that 16,000 are uninhabitable. Shetler has a plan to stem the tide of flight, while making existing rowhouses accessible to senior residents.

Shetler, who previously spent a decade running programs and design for the Patterson Park Community Development Corporation, founded Trace Architects in 2007. The PPCDC, which had been founded to decrease area vacancies in a neighborhood rife with boarded-up buildings and urban blight, provided free design services for area residents and bought, renovated, and resold hundreds of rowhouses in the neighborhood.

But by the mid-aughts, Shetler says, "we were having fewer and fewer projects, which was a good thing. We wanted to do the same thing, renovating homes, but in different areas." Which is what Trace has done: primarily residential renovations across various Baltimore neighborhoods, plus a handful of commercial projects, new builds, and a school.

Nearly all of the city's rowhouses consist of a uniform layout: 800 to 1,200 square feet over two or three stories, living areas and kitchen on the main floor, two bedrooms and a bathroom upstairs. In Shetler's time with the PPCDC, he says, he came to understand how Baltimore residents use their rowhouses.

The current layout presents problems for two very different demographics of residents. In many instances, older residents with decreased mobility wind up living on the ground floor, with beds in dining rooms and chair toilets to make do. Many don't want to leave the neighborhood—many of Baltimore's communities, Shetler says, are deeply rooted, with homeowners who still reside in the houses in which they were born, and many seniors prefer to remain in mixed-age neighborhoods. And if or when staying becomes physically untenable, seniors often lack the resources to move.

Younger residents also have trouble with the layout of existing rowhouses. With small bathrooms, pass-through bedrooms, and little to no parking, they're often unfriendly to families with multiple children.

Trace's proposal, produced by Shetler with associates Heather Hairston and Matthew Campbell, begins with a very simple fact: "It makes a neighborhood more interesting to have people of different ages in it," says Shetler. "How can you preserve that with these narrow rowhouses? You look at the rowhouse block as a whole and then manipulate it as you want to."

His plan hinges on the acquisition of an entire city block's worth of rowhomes—easier than it sounds, he says. PPCDC acquired the specific block he presents here, which consists of 19 contiguous two- and three-story rowhomes that the nonprofit developed and sold between 2006 and 2009.

For Shetler's proposal, the townhomes become horizontally organized modules, rather than vertical units. Lower floors are converted to handicapped-accessible, single-story living spaces, with ramps to doors and recessed entries that offer outdoor space and eyes on the street for the homebound. Family units are split between lower and upper floors: slim, open-plan living and dining areas remain on the ground floor, while a spacious upstairs includes three bedrooms and two bathrooms.

"If you look at them as modules," he says, "a senior flat is two modules, and upstairs is three modules."

Within the block, the mix of ages would ensure activity and habitation; Shetler imagines commercial spaces on corners, to further increase community access to goods and services. The proposal hinges, he says, on increasing accessibility while making a neighborhood more desirable for residents of all ages.

"The traditional rowhouses are fine in wealthy neighborhoods because they're desirable. 'I can't park, but who cares, I can walk everywhere I need to be.' Or, 'There's a lot of noise, but I can walk to bars,'" Shetler says. "Here, I wanted to create a whole block of flats that would organize horizontally rather than vertically, a new way of looking at the rowhouse block to make it more desirable."

The problem of Baltimore's empty rowhouses won't be fixed overnight, central though it is: When protests raged earlier this year over Freddie Gray's death, they were concentrated in the areas of the city with the highest rates of vacancies. Plans and proposals for the abandoned buildings in such neighborhoods have included mass demolition and rehabilitation and use as low-income and homeless housing. In Shetler's experience, if a neighborhood shares borders on two sides with densely-populated, strong communities, it has a higher chance of becoming more stable.

Retrofits that would allow elderly residents to remain in their homes, and surrounded by neighbors of all ages, might be a step toward community strength, Shetler says: "By doing this, you may keep people in a city or make the neighborhood a little more stable."

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· Baltimore coverage [Curbed]