Investigation, existing condition analysis, restoration design, construction administration
285 Central Park West
The St. Urban, also known as 285 Central Park West, was designed by Robert T. Lyons and completed in 1905. It is a 12 story tall Beaux-Arts style building with a copper-clad mansard roof. It has a cage-frame structure with cast iron columns, steel beams, draped mesh slab floors, and masonry bearing wall facade. The facade is comprised of limestone, brick and terra-cotta. It is heavily ornamented with detailed terra-cotta features.
Facade work
We were asked to perform a Facade Safety and Inspection Program (FISP) survey and report on the building, and address any unsafe conditions that were present. The facade investigation included visual observations of all facades, hands-on inspections of street facing facades and select rear facades, sounding 100% of terra-cotta, review of an existing FISP report, and review of probes.
Our detailed FISP report found a number of conditions that were unsafe or safe with a repair and maintenance program (SWARMP). Our design of extensive repairs included repairing brick cracks; replacing damaged or missing bricks; repointing open mortar joints; replacing damaged or missing decorative sheet metal lintel and sill caps; reinforcing steel lintels; repairing sheet metal; rebuilding the parapet at the rear elevation; removing an unused chimney; replacing a deteriorated steel post of a water tank; replacing damaged terra-cotta; pinning, patching or resetting terra-cotta elements; repairing the existing waterproofing; pinning brick masonry; pinning limestone; and replacing cracked limestone.
Foundation
During the facade inspection, we were also asked to investigate long term settlement damage at the north-east corner of the building. We observed all the accessible affected spaces within the building to determine the cause.
Our investigation found a damage pattern in the north-east portion of the building that was consistent with foundation settlement. No settlement damage was observed at the facade or elsewhere in the building. We determined that the damage was likely caused by the settlement of two columns at this corner of building. The north side of the building rests on old landfill and all of the other columns rest on concrete piers to rock; the two columns in question rest on the lower portion of the fill.
We designed a reinforcement scheme for the foundations of the two settling columns. The proposed work includes shoring of the columns with minimum interventions and installation of new piles and pile caps at least 5 ft away from existing columns as to not interfere with existing foundations. It also includes installing new grillage beams to transfer the load from the existing columns, and reinforcing the existing columns. The new piles are to bear on rock, to halt any more downward movement of the two affected columns and prevent future damage at the affected corner of the building.
Both of these projects required extensive coordination with the Landmarks Preservation Commission and the NYC Department of Buildings. We were able to successfully address the unsafe conditions at the St. Urban while retaining the historic building elements and also proposed actions that will prevent future damage to this important structure.
