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St. Luke’s School

New York, NY
  • St. Luke's School is located within the Greenwich Village Historic District.

This K-8 school wanted to nearly double the space in its existing 1950s building to accommodate its growing student base. The existing building was a 2-story, 27,000 sf steel structure. As is common in Manhattan, the only strategy for significant expansion was to build up.

A conventional vertical addition would have triggered a costly seismic retrofit of the existing structure. To avoid this and reduce the impact of the construction on the existing building below, Silman designed the addition as a completely independent structure supported on super columns.

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The eight 40-foot-tall super columns supporting the new addition are threaded through the existing structure to new independent foundations. The existing framing was modified to accept a new elevator and stair core.

The eight 40-foot-tall super columns supporting the new addition are threaded through the existing structure to new independent foundations. The existing framing was modified to accept a new elevator and stair core.

Two-story steel trusses at the addition’s longest cantilevers and spans help the building meet load and deflection criteria. They are exposed to the interior in several locations, adding visual interest. These trusses are supported on custom built-up steel girders cantilevering over the super columns below. The custom shapes were required to keep the girders shallow enough to fit between the new structure and the existing roof.

Silman coordinated the foundation design with the Port Authority of New York and New Jersey (PANYNJ), the agency that owns and operates the PATH train tunnel that runs beneath the northwest corner of the site. Four of the eight super columns are set back up to 30 feet from the face of the building and supported on 170-ton steel caissons; the other four super columns are supported on shallow spread footings. To isolate the new structure from vibrations due to passing trains, Silman detailed the columns bases to include 2-inch-thick isolation pads, with isolation material between all steel and concrete foundation elements.

St. Luke School’s new addition was constructed without any lost school days or student displacement. The school now contains a larger gymnasium, new classrooms and support spaces, and a future outdoor roof play space.

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