Two years ago, while walking his family's new puppy, Paul Boardman had the kind of epiphany only a real estate entrepreneur can have.
He was passing by 711 West End Ave. in Manhattan, a seven-story apartment building of red brick and squat windows between 94th and 95th streets that looked almost as if it were shrinking from the grand prewar buildings around it that are twice its size.
Boardman envisioned something equal in stature for the site. But tearing down 711 West End Ave. would be all but impossible, considering that most of its 144 apartments are rent-stabilized, giving their tenants a right to stay.
So Boardman came up with a daring plan. By threading a series of multi-ton support columns around the existing structure, a new 10-story condominium tower could be built. It would essentially sit not atop the old building, but above it, with its bottom floor hovering more than 80 feet in the air.
"We get to unlock the value of this site and create a building truly worthy of this great neighborhood without displacing any of the existing residents," Boardman said in an interview last week.
In a city where the only place to go is often up, adding floors to an existing building is nothing new. Rarely, if ever, is this work undertaken over an occupied apartment building. If it works, though, other developers might start stacking apartments, too.
"The idea is genius," said Jesse M. Keenan, research director at the Center for Urban Real Estate at Columbia University. "The execution will be challenging, but not impossible."
The soon-to-be downstairs neighbors are not so enthusiastic. Tenants in about half of the apartments at 711 West End Ave. have formed a group opposing the project, contending that the blueprints do not begin to convey what the project will look and feel like from below.
"I'm afraid for my life that any minute, one of these three-ton steel beams could come crashing through my wall," Stephanie Cooper, a resident of 47 years, said inside her two-bedroom apartment on the fourth floor. She originally paid rent of $267 a month, and now pays less than $2,000.
While building a 10-story building over a seven-story one might seem like a futuristic proposition, the engineering for 711 West End Ave. is quite conventional.
The top 10 floors will sit on a steel and concrete platform supported by a crisscrossing steel superstructure surrounding but not touching the lower building. Other than the shaft for a new elevator and fire stairs that will run from the lobby to the new eighth floor, the buildings are totally separate.
A roughly 6-foot gap will separate the roof of the existing 1952 building and the bottom of the new one because they must comply with different fire codes, though the facade of the art deco-inspired addition will obscure the gap. The idea is to unify the buildings visually but not physically.
"We hired all the best consultants, and it's pretty amazing what they've come up with," Boardman said.
The owners maintain that the project will be a boon for current residents as well as new ones, and not only because they get to stay. The plans also call for adding new windows and central air conditioning to all existing units, as well as a new lobby and a courtyard garden.