304 Park Ave South
Project Statistics
Project Name: Roof Replacement, Façade, and Structural Repairs at 304 Park Avenue South
Location: New York, NY
Client: SL Green Realty Corp
Completion Date: Ongoing
Service Type: Roof Replacement, Façade and Cornice Repairs, Structural Rehabilitation, Waterproofing, FISP ****
Industry/Building Type/Height/Units: Commercial Office, Historic Preservation (Listed on the National Register of Historic Places), 12 stories + bulkhead
Overview
304 Park Avenue South is a 12-story commercial building located in Manhattan’s Flatiron District. Originally constructed with a combination of pitched and flat roof areas over steel framing, it represents early 20th-century construction adapted for modern commercial use. The building is listed on the National Register of Historic Places and is a prominent example of early 20th century architecture adapted for modern use.
CANY has worked with the building owner for over a decade, first beginning with FISP inspections and related roof restoration and repairs in 2015. In the most recent campaign, initiated in 2020, CANY returned to address additional roof areas, many of which were found to be deteriorated or structurally compromised, as well as updating the façade inspections. This phase included extensive deck replacement, skylight upgrades, and coordination with FISP-required façade repairs.
The project benefited from CANY’s ability to coordinate across disciplines and anticipate field conditions. With both architectural and engineering expertise in-house, CANY delivered a unified design approach supported by detailed documentation, making it easier for the owner, contractors, and inspectors coordination at every stage.
CANY's Involvement
Services provided
CANY led comprehensive enclosure consulting and design services for a phased roof and façade repair program, including:
Existing conditions assessments and probes
Roof replacement and façade repair, design and detailing
Structural roof deck replacement strategy
Skylight and railing replacement
FISP inspection and repair coordination
Tenant safety planning
Special inspection support and construction-phase coordination
Scope of work
Full replacement of multiple roof areas, including structural deck repair or replacement:
Removal of deteriorated concrete planks spanning steel framing
Installation of new structural steel decking
Replacement of skylights, ladders, and perimeter railings
Comprehensive façade repairs including work at brick, terracotta, stone, and the copper cornice
Repair and reinforcement of deteriorated steel at façade interfaces
Phased construction sequencing to minimize disruption
Our approach and solutions provided
Main challenges
Discovery of widespread structural deck failure mid-project during the roofing work
Complex coordination between roofing, steel, and façade repairs
Maintaining building operations and safety during intrusive structural work in occupied building
Preservation expectations of the National Register of Historic Places
CANY's solution
Mobilized rapid investigation and non-destructive testing to assess deck conditions at roof replacement areas
Used in-house engineering to design structural steel replacement and reinforcement plans.
Replaced aging skylights with improved, energy-efficient units
Sequenced construction work to minimize disruption to tenants and interior operations
Preserved historic appearance using modern materials compatible with the original design
Provided highly detailed drawings and graphic documentation to support clarity and communication across all teams
Project Achievements
Key outcomes
Structural roof deck replaced and reinforced across multiple levels
New waterproofing and insulation systems installed
Skylights, railings, and access ladders upgraded to meet current code and performance standards
Façade successfully maintained with historic materials
High-clarity construction drawings supported smooth execution and stakeholder coordination
In-house engineers enabled fast, cohesive design decisions
A long-standing client relationship strengthened through reliable, adaptive service
Building History
Originally completed in 1904, 304 Park Avenue South is located at the corner of Park Avenue South and 23rd Street in Manhattan’s Flatiron District. In 1916, a two-story penthouse was added for the artist Jules Guerin, best known for his murals at the Lincoln Memorial. A second penthouse followed in 1925, serving as a private office for the then-Governor Al Smith and earning the nickname, “Tiger Room.”
Designed by Clinton & Russell, the building is a striking example of Italian Renaissance Revival architecture. The façade features a traditional base-shaft-capital composition in brick and terracotta, with decorative rustication, fretwork below fourth story-windows, decorative swags on the spandrels, and an elaborate cornice crowing the upper façade.
The building stands within a historically significant corridor that saw intense commercial development in the early 20th century. Once a residential area, Park Avenue South, formerly Fourth Avenue, transformed into a business hub during a period of rapid urban growth. Today, the area blends preserved architecture with modern office use, attracting technology and creative industry tenants.
Conclusion
This project showcases CANY’s ability to respond to evolving site conditions while maintaining precision and clarity. By integrating architectural and engineering expertise in-house, CANY streamlined structural decision-making and integrated repairs with ongoing enclosure work. Detailed drawings and graphic documentation supported clear communication across the teams, reducing delays, minimizing confusion and enabling better informed decisions on-site.
