Holes in plan to limit tower voids

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A city proposal aims to close a key zoning loophole — but some reformers say further action is needed


  • Extell Development’s proposed 775-foot tower at 50 West 66th St. includes a 161-foot mechanical void in its middle section, shown in grey in the rendering at right. Left: Snøhetta; Right: George M. Janes & Associates

  • A Department of City Planning rendering illustrates the agency’s proposal to tighten restrictions on mechanical void space. Image: Department of City Planning

  • The Department of City Planning’s proposal applies only to certain residential zoning districts, shown in this map. The agency plans to expand the geographic scope of the rule change in a follow-up proposal later this year. Image: Department of City Planning

The Department of City Planning last month issued its long-awaited proposal to reign in the development industry’s controversial practice of inflating building heights through the use of largely empty mechanical voids. But some observers worry that the city’s fix doesn’t go far enough to address the underlying problem — and that without further reforms, developers will simply turn to other zoning loopholes to win permits for ever-loftier towers.

Under city zoning law, spaces designated for mechanical use do not count toward the floor area calculations that in many districts effectively govern a building’s maximum permissible height. This exemption, combined with the fact that the city does not limit the height of mechanical spaces, has driven some developers to make use of ever-larger mechanical voids in towers’ middle sections. These vast empty spaces, which in some cases exceed 150 feet in height, nominally house mechanical equipment but are primarily intended to elevate the sightlines — and attendant dollar values — of upper-story residential units.

Such voids have become a popular target of reform-minded zoning activists, including Manhattan Borough President Gale Brewer and each member of the City Council’s Manhattan delegation, who claim that the proliferation of voids and other so-called zoning loopholes is undermining the intent of the city’s zoning resolution and producing taller buildings than planners ever anticipated.

In response to these concerns, Mayor Bill de Blasio requested last year that the Department of City Planning examine the issue. The agency’s proposal, issued Jan. 28, aims to discourage excessive voids through new regulations. One change would limit mechanical floor area exemption to spaces 25 feet tall or shorter; voids taller than 25 feet would count toward a building’s maximum allowable floor area. Additionally, if a building’s body includes multiple mechanical voids, each would need to be separated by at least 75 feet in vertical distance or the spaces would be counted toward floor area calculations.

The Department of City Planning explained in a release that the zoning text amendment “seeks to restore predictability of built form to New York’s high-density residential neighborhoods, ensuring that towers do not exploit zoning to vault above their neighbors through the utilization of largely empty enclosed mechanical spaces.”

East Side, West Side opposition

Two planned towers in Manhattan — one on the Upper East Side, one on the Upper West Side — have attracted local opposition for their envelope-pushing designs, each of which feature substantial voids.

The upper residential floors of the planned 510-foot tower at 249 East 62nd St. sit atop a 150-foot-tall octagonal platform of void space, leading detractors to label the project a “building on stilts.”

On the West Side, The Department of Buildings initially approved plans for Extell Development’s proposed 775-foot tower at 50 West 66th St. that included a 161-foot mechanical void on its 18th floor. But in January the agency notified the developer of its intent to revoke the permit following an audit of the building plans, citing concerns with the void. (Whether the project will proceed as planned is as yet unclear and will hinge on whether Extell can adequately address the city’s objections.)

Even if the city’s zoning text amendment is enacted, some zoning experts believe the proposal’s limited scope makes it all but inevitable that developers will use alternate means to achieve similar results.

“I’m thrilled that they’re responding to the issue, but I wish that they would have done more,” said George Janes, a planning consultant who prepared zoning challenges regarding both 249 East 62nd St. and 50 West 66th St.

Janes noted that the city’s proposed zoning change only applies to enclosed spaces — meaning that developers could skirt the new restrictions by simply removing two walls from any impacted voids, rendering the voids outdoor spaces exempt from floor area calculations.

“If it’s so easy to get around the closing of one loophole by using another tactic, who wouldn’t do that?” he said, adding that he is hopeful the amendment will be strengthened as the city considers public input.

A more aggressive approach

Another predictable result of the new rules, said Andrew Berman, executive director of the Greenwich Village Society for Historic Preservation, is that rather than clustering enclosed mechanical space in a single large void, developers will instead place 25-foot voids at regular intervals of 75 feet “with no requirement whatsoever about there being any actual necessary mechanical equipment in each of those floors.”

“The city’s proposal seems almost designed to do as little as possible about the problem,” Berman said.

Upper West Side Assembly Member Linda Rosenthal has introduced state legislation that takes a more aggressive approach than the city’s proposal. Rosenthal’s bill would place stricter limits on mechanical void space while also discouraging excessive floor-to-floor heights on non-mechanical floors by mandating that floor area calculations correspond to ceiling height.

For now, the city’s proposed text amendment only applies in certain residential districts, primarily in Manhattan. The Department of City Planning intends to put forward a second amendment expanding the geographic scope of the proposal later this year.

The Department of City Planning is briefing community boards on the proposal this month, after which the agency will consider their recommendations and hold a public hearing, before ultimately sending the proposal to the City Council for approval.

The East Side’s Community Board 6 passed a resolution in support of the city’s proposal at its Feb. 13 meeting, but also called for further amendments to “close other known zoning loopholes used to the same effect as mechanical voids.”

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