A widely maligned plan for a 32-story residential tower on the Upper East Side that has been dubbed the “building on stilts” has been halted for fire safety concerns, offering a potential victory to community opponents who have fought the design.

In a March 4th letter addressed to four elected officials and Friends of the Upper East Side Historic Districts, Thomas Fariello, the acting Department of Buildings commissioner, wrote that the city is asking the developers of 249 East 62nd Street, Real Estate Inverlad and Third Palm Capital, to submit written approval from the FDNY “concerning the proposed conditions at the intermediate level outdoor space, including but not limited to FDNY emergency access and safety operations.”

The “outdoor space” refers to the central design feature of the building — an exposed gap surrounded with pillars between the 13th and 16th floors that would effectively raise the upper half of the 510-foot building — that was widely seen by real estate observers as a mechanical void, a space meant to house mechanical equipment, but which are now being enlarged by luxury developers to maximize building heights.

The DOB has to date refrained from calling the section at the Rafael Viñoly-designed project a void. That, along with limiting its objection to fire safety, leaves open the question over whether the city intends to curb the much-criticized design element.

The answer, according to some, rests on a set of new zoning rules that is currently undergoing the public review process. In January, City Planning issued a zoning amendment proposal which, among other requirements, would make voids taller than 25 feet would count toward the residential project’s permitted floor area. The planned changes were spurred by criticism of 249 East 62nd Street, which last year led to Mayor Bill de Blasio asking the Department of City Planning to examine the issue of mechanical voids.

Shortly after the announced zoning amendment, the DOB told Gothamist that the plan for 249 East 62nd Street would not be affected by the proposed regulations because the project did not include a mechanical void. Instead, a DOB spokesman said the feature was considered “outdoor space” and that the design had precedent in other buildings across the city.

The statement by the DOB at the time caught local residents and elected officials by surprise, especially since the department had in January issued a threat to revoke the permit for a 775-foot condominium tower on the Upper West Side, citing both its unusual use of a 160-foot mechanical void in a residential building and fire safety concerns.

On February 15th, state Senator Liz Krueger, Manhattan Borough President Gayle Brewer, Council members Keith Powers and Ben Kallos, wrote a letter to the DOB citing its actions on the Upper West Side project. “Regardless of whether the void in the building proposed at 249 East 62nd Street is enclosed or open air as described to the press, we believe you must also refer this building to the FDNY.”

On Thursday, Kallos said the letter was intended to "call attention to the disparate treatment by the DOB between East Side and West Side." He said he was glad that the matter had been referred to the FDNY, noting that the measure "will ultimately keep residents safe."

He said he hoped City Planning will address what he views as a flawed design at 249 East 62nd Street, adding, "I would be interested to see if government can move at the same speed on this issue as it does for developers."

In an email to Gothamist, a DOB spokesman wrote, "The applicant must resolve all DOB objections in order to forward with the project."

Rachel Levy, the executive director of the Upper East Side Historic Districts, which has filed a zoning appeal against the project, said her organization was pleased that the DOB has referred the building’s design to FDNY.

In a statement, she added: “That said, we remain deeply concerned that unenclosed voids or stilts will not be addressed by the DCP’s proposed text amendment. We continue to urge the City to revise this aspect of the proposal so that it impacts 249 East 62nd Street, one of the most egregious offenders of the mechanical void loophole, and a project that has catalyzed both FRIENDS’ and DCP’s work on this issue.”

George Janes, a planning consultant who has worked with Friends of the Upper East Side Historic Districts, said the onus was now on City Planning. As the zoning amendments have made their way before community boards on the Upper West Side and Upper East Side in recent weeks, he and others have pressed the city to regulate what they consider to be “open air voids."

The City Planning Commission is scheduled to hold a hearing on the proposed amendments next week.

“It’s not DOB’s decision,” he said. “They just got to enforce the rules. Right now, DCP has put together a solution but left a big loop hole in it. Are they going to do anything about it?”