Rod Davis, left, and Mark Manivong discuss an upcoming neighborhood meeting to organize opposition to a five-story “pop-up” on A Street. (J. Lawler Duggan/For The Washington Post)

The two sides of the 1500 block of A Street NE look very similar. Both are lined with idyllic two-story, single-family homes. Most of the houses have stoops and small front yards.

The north side is likely to stay that way; it’s off-limits to developers and businesses. But on the south side, there may soon be a five-story condominium looming over the neighbors.

That’s because under the District’s zoning code, the property at 1511 A St. has few restrictions on what can be built there, beyond limiting the height to 50 feet. And the new owner, developer Taiwo Demuren, wants to “bring to the neighborhood condominiums that will not be pricing out those who want to live in Capitol Hill,” he said.

Residents opposed to Demuren’s plans say the development would not fit in with the neighborhood.

“We’ve had these 100-year-old homes here forever, and nobody ever thought this was zoned commercial,” said neighbor Brian Weeks.

The house at 1511 A St. was left abandoned when its occupants died in 2004. The garage units behind it fell into disrepair and became home to drug dealers and high school students looking for a place to hang out, according to neighbors, who have erected flood lights and cameras to deter vandals.

Eight years later, Demuren bought the 90-year-old house for $1.5 million. He wants to replace it with an 18-unit condominium development. And despite growing opposition from neighbors, it is very possible he will be able to do so.

Residential neighborhoods that stretch from Union Station to the D.C. Armory include pockets that have been zoned for commercial use. Neighbors think their block’s zoning dates to the 1890s, when the nearby Car Barn condominium complex was used to store and repair streetcars. D.C. Office of Zoning Director Sara Bardin said the zoning hasn’t changed since at least 1958.

“It’s just something that’s been overlooked over the years,” said Mark Manivong, who lives across the street from the proposed condominium.

Manivong and his husband, Sam, moved into their home in the Capitol Hill neighborhood 11 years ago. The daily commute to the Library of Congress and the affordability of the house made it an easy choice. Since then, they said they have come to love the friendly nature of the neighborhood. They appreciate every sound, from the barking dogs to the band at Eastern High School occasionally marching down the street.

They don’t want the condo, but they know this fight is one occurring throughout the city.

“We’ve seen these buildings going up all over the place, and they’re destroying the character of the neighborhoods,” Manivong said.

Residents have been pursuing zoning ­changes to the block. They have also applied to the D.C. Historic Preservation Office for special historical designation for the neighborhood, located near Pierre L’Enfant’s original border of the city.

And they’ve enlisted the help of their local Advisory Neighborhood Commission, which supports rezoning and has sent a letter to Zoning Administrator Matthew LeGrant to “investigate the proposed construction at this address and determine whether any zoning relief is required.”

“Can they really reasonably put 18 units in there?” ANC 6A Chairman Nicholas Alberti said in an interview. “It’s a good question. It’s hard to believe.”

Neighbors said they had trouble reaching Demuren to discuss their concerns. They met him and the project’s consultant, Toye Bello of Bello, Bello and Associates, on April 10 at an ANC meeting — after Demuren learned of the meeting during an interview with The Washington Post.

“We didn’t know they were looking for us,” Demuren said.

Neighbors, developers and city officials are scheduled to meet again Thursday at the home of neighbor Rodney Davis.

Demuren and Bello said they are not seeking a change to city regulations, which would then give weight to community input on the project.

“It’s really not a project that is subject to public scrutiny,” Bello said.

Demuren added: “I can’t stop the development being there. If we don’t do it, somebody else will.”

Demuren doesn’t have permission to build yet. The D.C. Department of Transportation still has to approve his plan. In addition, District regulations mandate the final property include a parking spot for every other unit, totaling nine spaces. The D.C. Department of Housing and Community Development also has to accept the proposal, which must include some affordable housing to qualify for additional floor area.

But residents say they know that stopping the project is a long shot.

“I’m not optimistic we’ll be successful,” said Davis, “and it’s certainly a cautionary tale to people to see how their neighborhoods are zoned.”