Correction: An earlier version of this article incorrectly said that the newly approved rules became effective immediately. The rules will go into effect in one to two weeks.

A line of rowhouses on the eastern side of the Capitol Hill neighborhood. ( Amanda Abrams/For The Washington Post)

The District’s Zoning Commission gave final approval Monday night to new regulations governing the “pop-up” homes sprouting up in some of the city’s gentrifying neighborhoods, reducing the maximum height of single-family rowhouses to 35 feet from 40 feet.

In a surprising reversal from a preliminary vote in late March, the commission also voted to limit developers to building two “by-right” condo units in a pop-up, a renovated rowhouse with an added story or added stories often towering over neighboring homes. A third or fourth unit would require a special exception from the city.

Monday night’s vote ends more than a year of impassioned debate across the District over its historic rowhouse aesthetic. Critics of pop-ups argue that the looming structures block views, sunlight and even neighbors’ chimneys while crowding neighborhoods and increasing competition for parking.

Pop-up supporters contend that to accommodate growth, the District needs to enable homeowners and developers to expand the city’s limited housing inventory in one of the few ways it can — upward.

The five-member commission spent most of its time Monday night debating whether to cap the number of by-right condo units at two, rather than four. At one point, the debate got testy after Marcie Cohen, the vice chair, expressed support for developers and homeowners who want to retain as much of their property rights as possible.

“We’re a growing city,” Cohen said. “We need to have the flexibility to enable other households to come into neighborhoods, and we need the flexibility [for owners] to expand within their own space.”

Cohen was echoing many pop-up supporters who maintain that a few pop-ups have given the extended rowhouses a bad reputation and that many families need the extra room if they are to stay in the city, rather than move to the suburbs.

But Anthony J. Hood, the commission’s chairman, wasn’t buying Cohen’s argument.

“I know we need to put in some controls,” Hood said. “Is this going to be the ‘fix-all’? No, but right now we have to do something. . . . Let’s keep it real.”

The new regulations affect only neighborhoods in the city’s “R-4” zone — which includes some of the city’s most vibrant residential areas, such as Capitol Hill, Adams Morgan and Columbia Heights. The regulations go into effect in one to two weeks.

Some developers with pop-ups already in progress are protected from the new rules. They include: pop-ups with three or more units whose applications had been “accepted as complete” by the city’s Department of Consumer and Regulatory Affairs by July 17, 2014; pop-ups of three or more units that have received approvals from or had hearings before the Board of Zoning Adjustment, the Commission of Fine Arts or the Historic Preservation Review Board before Feb. 1; and pop-ups with only two units whose applications by the DCRA had been accepted as recently as Feb. 1.