The Spence School

Question: How do you make a structure larger if you can't build an addition onto it?

Answer: Just dig a hole underneath it.

Simple, right? Not exactly.

But that was the challenge faced by the project team that renovated the former Rose Mansion at 56 E. 93rd St. on behalf on the Spence School, a private, all-girls school.

Because it is a landmark structure and the façade must remain intact, an addition could not be built on top of it. And surrounding homes in the residential neighborhood where it is located prevented additions from being built to the east or west of the mansion.

To create the additional space, approximately 6,000 cu. yds. of bedrock were removed from beneath the existing structure to make room for what would become a gymnasium. To support the building during excavation, a 12-ft.-deep and 80-ft.-long steel truss was created and the weight of the building was transferred from the original support system to the new one.

The truss is now hidden within the structure of the building.

"The site has extremely limited access," said a jury panel member. "Maintaining the existing structure during construction had to have been difficult."

One of the last mansions built in New York City, 56 E. 93rd St. was completed in 1931 for William Goadby Loew, a stockbroker and sportsman. The architect, A. Stewart Walker of Walker & Gillette, worked on the house with his wife, Sybil, who was a decorator.

Among some of the finer details included in the mansion are Georgian pine paneling and Corinthian columns and pilasters in the drawing room.

Spence School bought the mansion in 1999 for $15.5 million from the Smithers Alcoholism Treatment and Training Center with plans to turn it into a school for 241 pupils in kindergarten through fourth grade. The rest of the school's 622 pupils attend class at the school's main building at 22 E. 91st St.

To serve the needs of the new school, plans for the former mansion called for building 15 classrooms, a gymnasium, dance room, music rooms, computer labs and a science room.

The project team worked with the New York City Landmarks Preservation Commission to replicate and preserve existing elements of the building. The original slate, lead-coated copper and limestone were saved and reused where possible. Internal architectural elements such as the pine paneling in the original drawing room were removed, refurbished, returned to the site and reinstalled piece by piece.

Impressions were taken of the plaster elements so they could be recreated. The recreations were then installed in place of the originals in the entry hall and drawing room.

The original penthouse was turned into a fifth floor of classrooms with a skylight window running along the north side of the floor. This floor sits under a sloping roof and is set back from the façade so that it cannot be seen from the street, a requirement under city landmark regulations.