Buildings with sections that seem to hover in Midair

Ask a child to draw a picture of a skyscraper and they’ll probably sketch a familiar form: perhaps a skinny rectangle standing on its end, or a tapered block that culminates in a pointed spire. After all, for more than a century, that’s typically how tall buildings have been designed.

But in New York, where land is scarce and the streetscape is increasingly crowded, a growing number of residential projects are turning the conventional skyscraper on its head. By building with cantilevers, they start narrow at the street but expand as they rise, more lollipop than traditional wedding cake.

Despite the structural challenges inherent in making large parts of buildings seemingly hover in midair, there are many potential advantages to doing so, depending on the limitations of a building site. Sometimes, pushing more of a building’s allowable square footage up to higher floors by adding cantilevers is a way to create more apartments with better views and light. Other times, when developers are limited by a height restriction, building sideways over a neighbor is the only way to maximize square footage as part of an air rights deal. In still other cases, it’s about sidestepping competing towers, creating more appealing space at ground level or simply realizing a design statement that can help a new project stand out from the crowd.

“Cantilevers offer a nice element of drama to the form of a building,” said Michael Kirchmann, an architect who is the founder and chief executive of the development company GDSNY, which recently completed the Emerson, an eight-unit condominium at 500 West 25th Street where the top floors cantilever toward the High Line. “A cantilever just adds to that dynamism and excitement people have in unraveling in their heads how a building stands up.”

While cantilevers might be thrilling to look at, they also offer real rewards for residents and developers in many cases. “Generally speaking, the further you get up into the building, the more valuable the space becomes,” Mr. Kirchmann said. “So, it’s not only an architectural thing, but it can become financially very beneficial for a project as well.”