In an unusual curbside debate in Park Slope, angry residents and a developer volunteered their time to argue informally over plans for a controversial Carroll Street apartment complex.

The developer, Ashwin Verma, of Black House Development, appeared voluntarily before his unfinished 580 Carroll Street building, off of Fourth Avenue, to address community concerns about the project.

He was met by a few dozen residents who gathered to protest Verma’s application to the Board of Standards and Appeals (BSA) for a variance request to build additional townhouses on the property.

Verma’s original plans called for a 17-unit, five-story building.

The developer recently requested a variance (which, if approved, would be his second for the project) to build an extra four, three-unit brownstones on the site. The added units would increase the site’s floor area ration (FAR) by 33 percent.

Verma and his business partner, Sean Ludwick, are proposing to build the houses on a patch of land on the property setback from Carroll Street that they first promised to set aside for a garden.

(The current, under-construction building sits behind the open land, on the site’s south side, which faces Garfield Place).

The site appears large enough to accommodate the additional buildings, though residents and community activists contend the variance would break existing zoning laws.

“The community fought for those zoning laws,” said Brad Lander, the chair of Community Board 6’s Housing and Community Development Committee and a candidate for City Council. “For these guys to want to [ignore the zoning rules] solely to get a higher return isn’t right.”

In a letter to the BSA protesting the variance request, Lander pointed out that it would violate existing R6B zoning in the area, which was put in place to preserve the character of the surrounding blocks of largely two- and three-story family homes.

Josh Skaller, who is running against Lander in the 39th Council District race, said the divisive debate over the project proves “the need for a real community-oriented development process in Brooklyn.”

“At this point the community is completely within its rights to” demand that the BSA reject the variance request, Skaller said.

Verma defended the application. He said the additional units would help pay for the additional construction expenses incurred when he discovered a below ground electrical substation on the site that need to be removed.

He said he has tried reaching out to the community, as in the case of the sidewalk debate, to ask “what can we do so that everybody comes out a winner.”

“I’m not Mr. Perfect Developer. I’m trying to do the best I can,” Verma said. “We’re investing a lot of money in this neighborhood.”

He declined to say how much. He said construction on the project is scheduled to be finished by November of this year.

Lisa Fane, a Park Slope resident who lives a few blocks from the site, said the building would be out-of-context in the neighborhood.

“Every time you put up [a building] that is just too big you take something out of the community,” Fane said.

She said zoning laws, created to protect the aesthetic and community spirit of a neighborhood, must be preserved.

“We really have to draw the line,” Fane said. “This is a really good example.”