• NYC Mayor Mamdani wants to build 200,000 new homes.
• Some of these new housing projects will be on land the city already owns.
• An economist told Business Insider that the plan may face funding hurdles, but would boost supply.

Zohran Mamdani is making a big bet on turning city-owned property into affordable housing.

The New York City mayor plans to oversee the construction of 200,000 affordable homes across the five boroughs. It's a significant undertaking that will require new builds, hotel and office building conversions, and widespread rezoning.

To control costs and limit red tape, the Mamdani administration is encouraging new development on existing public land, like converting libraries into mixed-use buildings or building on unused parking lots. If successful, a supply boom could help lower-income New Yorkers access housing and put downward pressure on overall prices.

The administration's goal is to identify public sites to support at least 25,000 new affordable housing units over 10 years. Ten projects — which are likely to yield a few thousand apartments — are currently in planning and development stages.

Building on city-owned property is "not a silver bullet," said Jake Krimmel, senior economist at Realtor.com. But it's one lever City Hall can pull.

City-owned land could be a piece of the affordable housing puzzle

A majority of New Yorkers spend more than 30% of their income on housing, the threshold economists define as unaffordable. Business Insider has heard from single moms who moved in together to save on rent, parents who are making just above the threshold for benefits, and six-figure earners struggling to make ends meet.

The city owns and leases a staggering amount of land, but not all of it is suitable for housing. "A lot of the city-owned land is not necessarily the easiest thing to build on because of zoning rules or parcel sizes and shapes," Krimmel said.

An analysis by the New York University Furman Center found that about 10,000 of the 15,000 plots in NYC's portfolio are currently zoned for residential use. A third of city-owned lots are overseen by the Department of Parks and Recreation, suggesting they may already be in use as parks, open public spaces, or sports facilities.

Buildable space is also a consideration. Krimmel said a very limited number of vacant lots in the city clear both the size and zoning bar for housing. That means the city will need to get creative with existing developments; Krimmel suggests stacking housing on top of civic buildings where possible.

He added that a public land construction push won't solve all of NYC's housing woes, but "if you're trying to make good policies, you need to leave no stone unturned." The city turning to existing public land is a great idea, he said, though selling it to developers for affordable housing use could be another financially-smart option.

"The city has valuable assets on its books," Krimmel said. "The question is whether it deploys them by building itself or whether it attaches affordability requirements, upzones, and lets other developers carry the financing and operations."

To reach its goal of 200,000 new affordable units, the Mamdani administration will also need support and resources from City Council, Albany, private developers, and taxpayers. As my colleague Juliana Kaplan reported, part of the reason New York is so expensive is it's a desirable place to live — which is unlikely to change anytime soon.

The Mayor's Office hopes its proposed rent freeze, universal 2-K childcare program, fast and free bus pitch, and other affordability initiatives will help lower New Yorkers' cost of living in the meantime. These initiatives go hand-in-hand with housing access, the mayor said.

As he told a crowd in Queens last month: "We will no longer speak in the language of promise. We will speak in the language of the present. We will build more homes."

• NYC City Hall released its detailed plans for affordable housing.
• Mamdani is supporting new construction, apartment-friendly zoning, homebuyer assistance, and more.
• The mayor hopes the plan will help lower- and middle-income New Yorkers.

Zohran Mamdani has ambitious ideas for New York City housing.

The Mayor's Office dropped its detailed policy plan — called "Block by Block" — on May 26, outlining goals to build more apartment buildings, convert unused offices and hotels into living space, and help residents navigate one of America's most expensive housing markets. Housing access has been a cornerstone of Mamdani's affordability agenda, with buzzy promises to freeze the rent for a large swathe of NYC apartments and address "bad landlords."

"When New Yorkers can afford a home, they can afford to dream," Mamdani said at a press conference Tuesday morning.

From construction to creative living solutions, here are Business Insider's biggest takeaways from City Hall's plan.

Boosting building opportunities

New York needs to build, baby, build. Vacancy rates hovering at historic lows are one of the biggest factors pushing up rents in the city, and Mamdani's blueprint lays out a slew of measures that aim to both reduce the costs of building and get more stock online.

Part of the plan is to simply build more housing, with a goal of 200,000 more homes in the next ten years. That's underwritten by $2.5 billion allocated towards more building from the mayor's budget, with the homes built subject to regulations that bolster construction workers' pay and benefits.

City Hall also wants to build more on public sites like Sunnyside Yards, a rail hub in Queens that sits between several bustling neighborhoods. That proposal would connect the neighborhoods currently separated by rail tracks, and build a deck over the rail infrastructure that could house what the report calls "a new complete neighborhood." The report also notes that the city would need federal support to build that new neighborhood — part of Mamdani's pitch to Queens native Donald Trump in early 2026.

Some proposals hinge on existing (and future) buildings. One is a program that would lower insurance costs for affordable and rent-stabilized units, which have seen soaring premiums. The plan says it would infuse $100 million to help fund a newer, more affordable insurance program, with a goal of both keeping costs more stable for current housing and saving the city money on new builds, since it currently has to subsidize those higher insurance prices.

Other aspects of the plan include expanding access to a water affordability benefit for those in affordable housing, and expanding a program that helps rental buildings and income-restricted co-ops improve their energy efficiency. The plan also aims to improve elevator service in public housing, and address leaks and plumbing issues in those units.

Supporting creative housing solutions

Through partnerships with developers and revised zoning policies, the mayor plans to convert some existing commercial buildings into apartments. The city said the recent overturning of a decades-old state cap on new developments would allow more NYC buildings to be allocated toward housing.

Both the local and state governments are working to convert the historic, and currently vacant, Stewart Hotel in midtown Manhattan into permanent housing for 550 households. Roughly half the units will be dedicated to providing affordable options for formerly-homeless and low-income households, per the plan. Some of the buildings' square footage will also be dedicated to providing on-site social services for tenants.

A largely vacant commercial skyscraper on Brooklyn's Flatbush Avenue received zoning approval in March. The building, which is on city-owned land, will be converted into 1,200 apartments, 350 of which will be "deeply affordable." Former private office building 100 Gold Street — which currently houses various city agencies in lower Manhattan — will also be converted into 3,700 apartments, 900 of which will be permanently-affordable homes.

The city also said it is trying to make it easier for New Yorkers to build accessory dwelling units (ADUs) on their property. That includes a program to help residents navigate their hyper-local zoning laws for ADUs, especially in historic districts. The city plans to streamline permitting for manufactured ADUs, which are significantly cheaper than custom-built units, making them easier for property owners to install for use by renters, elderly family members, or guests.

Beyond building more housing, Mamdani plans to begin a pilot this year to legalize basement apartments in the city. This will make it easier for homeowners to ensure their basements are up to code and can be made into safe apartment units. Homeowners who participate in the pilot this year will receive some financial support from the city to install smoke alarms, test for contaminants, and more.

Helping New Yorkers navigate the housing market

NYC is notorious for its cutthroat housing market, and renters make up 70% of city residents.

The Mamdani administration said it is taking steps to curb "bad landlords" by strengthening code enforcement and taking action against property owners who harass or neglect their tenants. The city is already hosting "rental ripoff" hearings in all five boroughs so that New Yorkers can share their concerns directly with City Hall, and the mayor said he is strengthening legal avenues for tenants to expedite emergency repairs. Mamdani also said he supports the development of tenant unions, which help renters collectively protect their rights. This goes alongside plans to reduce evictions and speed up cases in housing court.

City Hall wants to make New York more affordable for buyers, too. Mamdani is set to expand an existing downpayment assistance program to serve up to 300 lower-income first-time homebuyers. A new mortgage assistance program will provide repayable, no-interest loans to help low-income homeowners resolve mortgage problems.

The mayor added that he is moving forward on plans to freeze the rent in NYC's rent-stabilized apartments alongside City Council, but the policy has not yet been implemented.

The success of a rent freeze — alongside many of the other programs in the city's housing plan — will hinge on legislative support and funding at the local, state, and, sometimes, federal levels. Still, the mayor is feeling confident.

"Combined, these efforts will lead to growth beyond anything New Yorkers have seen in generations," Mamdani said. "For some, the dream of home ownership will finally be within reach. Others will be able to sleep easily in homes they no longer fear losing."