St. Luke's Hospital Conversion

the challenge

Abandoned for decades until the initiative of a tax-credit rehabilitation project commenced in 2016, pre-war St. Luke’s Hospital in Morningside Heights has been restored and transformed into a high-end residential complex.

We provided integrated engineering services for the project, which included retrofitting four Beaux-Arts mid-rise masonry buildings surrounding a courtyard with a carriage house, plus 40,000 square feet of new infill. All of St. Luke’s original finishes, limestone façades, wrought iron ornamentals and verdigris have been meticulously conserved and restored to their Gilded Age grandeur.

The project was not without its challenges; the historic pavilions required extensive upgrades to provide thermal comfort and daylight to new tenants. Old connectors in a state of disrepair were demolished and replaced, and new glass connectors integrate the carriage house with the four pavilions. Historic assemblies required interventions in weatherproofing, structural soundness and building envelope durability.

here's how

Designed by renowned architect Ernest Flagg and built between 1897 and 1928, the former hospital complex at 30 Morningside Drive occupies an entire city block on Morningside Park in Upper Manhattan. Listed on the National Register of Historic Places, the complex has been converted to residences.

Envelope Upgrades

One of the goals for the restoration of historic building envelope, including the exterior walls, cornices, copper and slate roofs, was to maintain their historic fabric and character. We surveyed and restored the brick and limestone masonry façades with various stabilization and repair techniques such as masonry pinning, repointing, crack and patch repairs and limited replacement.

The roof was repaired to maintain original sightlines and the character of the copper-clad ornamental dormers. We evaluated the historic, sloped roofs made of slate tiles on hollow terra cotta book tile or cinder concrete backup and repaired the roofs with new framing. The slate roof assembly was replaced atop new steel sub-framing with spray-foam insulation.

Single-pane windows were replaced with high-performance aluminum windows. The team chose an architectural window system finished with Kynar with tri-sealed insulated glass units filled with argon, with a lift balance that matches the original pulley system.

Structural Interventions

The structural scope included floor openings for new central stair and elevator cores in three buildings. The team incorporated 40,000 square feet of new floor area via three separate seven- and nine-storied infill zones. The historic buildings employed different structural systems including terra cotta flat arches, draped slabs and exterior masonry bearing wall constructions and required structural adaptations.

We assisted in linking the historic pavilions to the centrally located carriage house via a new glass connector, creating an open lounge space with a library and catering kitchen where tenants can mingle. The connector was constructed of dual pane insulated glazing units with minimal framing members, allowing the form to disappear against the backdrop the grand architecture.

Guided by preservation principles, we oversaw the removal and replacement of the building components, which was kept to a minimum by strengthening the original assemblies and performing in-situ repair techniques to retain the existing elements, such as masonry, ornate copper window surrounds, cornices, belt courses and wrought iron railings and verdigris. The assemblies of projecting historical ornamental elements were testing and analyzed to assess the performance and structural upgrades were made. Treatments for corrosion, section loss, and rust staining were also implemented in addition to the structural retrofit.

results

Because the new components introduced into the buildings relied strongly on the performance of the existing structure, the retrofit had a great impact on the success of the restoration. The restoration and preservation of the buildings was performed in accordance with the Secretary of Interior’s Standards for Rehabilitation. Since we were able to preserve the historic fabric and character of the complex, the historic preservation techniques made the adaptive reuse of the complex a success.