City Of Yes Could Eliminate Longstanding Height Restriction. Will Developers Act?

To most developing in New York City, the “sliver law” is just a fact of building. 

In a city where the sky’s the limit, the 41-year-old rule in the city's zoning code restricts buildings on lots narrower than 45 feet to a height no taller than 100 feet or the equivalent of the width of the adjacent street, whichever is less.

But as Mayor Eric Adams attempts to unlock as much new housing supply as possible under his City of Yes zoning reform proposals, the longstanding rule could be struck down, allowing narrow towers to rise. 

That could unlock 51M SF, or nearly 76,000 new units of housing, according to an analysis by PropertyScout provided to Bisnow. 

The review combed through city building, property and permit records of development sites that are affected by the sliver law, have air rights intact and are less than 75% built under all other zoning codes. 

“The reality is, if we want to create more housing in this city, there's only so much land,” Ariel Property Advisors founding partner Michael Tortorici said. “We have to build up.”

Unlike typical neighborhood rezonings, the Adams administration's City of Yes proposal looks to up housing production by modernizing outdated citywide regulation. Eliminating the sliver law is among the various updates proposed. 

The multifaceted proposal has become best known for its plan to make office-to-residential conversions possible in more areas of the city. However, its goal to build “a little more housing in every neighborhood” includes smaller changes, like legalizing housing in backyard cottages, garages and basements, which all add up. 

New York City has called for 50,000 units of housing to be created annually for the next decade to address the ongoing housing crisis. By the end of March, just 83 projects containing less than 3,000 units have sought foundation plan approval, according to the Real Estate Board of New York.

“It's been several years of pretty depressed development site trading activity,” Tortorici said. “The easing of some of these rules, making it a little easier to build in the city and maybe giving bonuses here and there, all of that is it's going to increase the viability of development.”

The sliver law was among the Department of City Planning’s first attempts at form-based zoning. The code was meant to prevent buildings from being uncharacteristically narrow and tall for residential neighborhoods. 

Instead, in many areas, the opposite has occurred. Overtime, the rule has resulted in small lots being surrounded by much taller structures.

“It’s like a missing tooth in the block,” Karp Strategies Director of Real Estate and Economic Development Annie White said. 

Throw a dart on a map of Manhattan and it’s likely to land on an example of blocks that look like a six-year-old's mouth. 

At 277 Fifth Ave., a 55-story residential building towers over NoMad. Directly next door, three buildings are subject to the sliver law, keeping most of the block low to the ground. 

The restriction has also led many property owners to sell off their air rights. To preserve views for the 130-unit condo, and prevent other assemblages from being stitched together, Victor Group and Lendlease Development cobbled together unused development rights from eight different parcels for 277 Fifth, the developers told The New York Times in 2017.

There are approximately 21,000 properties where the sliver law currently applies, but air right sales have cut the total down to 7,500 properties with existing development rights, according to PropertyScout. 

“There are a lot of parties at stake here, and they're not all going to be happy,” Core Real Estate agent John Harrison said. “You have supply and you have demand, but you also have the previous demand, which are those that purchased previously thinking that they were buying a limited edition view.”

Harrison works on the sales team for 501 Third Ave, a 34-floor residential building, in Kips Bay. Three buildings next door are limited by the sliver law. 

On the Upper West Side, a new development at 15 W. 96th St. rises 22 stories, but has a lot frontage of just 60 feet, slightly larger than the 45-foot restriction. The development is the result of an assemblage of three townhomes.

“It can be really hard to go up on a 40-[foot] lot because it's just so narrow. But with all the technology and the engineering in today's world, everything is possible.” said The Agency’s Shane Boyle, who previously represented the building. “If it is possible, does that actually pencil out?” 

The dimensions of the lots naturally allow only so many units to fit per floor, even if the zoning restriction is lifted, Boyle said.

“There's definitely a huge shortage of housing, but is that actually going to solve the housing problem when you're selling multimillion-dollar apartments that not everybody can afford?” he added. “Probably not.”

In an analysis of several sites encumbered by the sliver law, structural engineering firm KTA founder Kyle Twitchell said that the need for elevator shafts and stairways often limit both the number of units in the building and the size of those units. That can cause developers to shy away from construction. 

“It makes sense. You can do it,” Twitchell said. “I don’t know a developer that will do it.”

But White, who spent five years at city planning before joining Karp, said that even if a few developers take advantage of the change it would help tackle the affordable housing crisis.

“Both government and industry professionals need to be really evaluating all opportunities and leaving no stone unturned to address the problem,” White said. “Small bits of housing across the city does end up adding up to a lot.”