Tweed Courthouse: New Approach to Life-Safety Management in a Landmark Public Building

JOHN G. WAITE and NANCY A. RANKIN

When restoring monumental public The History and Architecture of Tweed city by reinstituting home rule, provid- buildings for new uses, a perfor- Courthouse ing jobs for immigrants, and advancing many public construction projects. mance-based approach to building- The Old New York County Court- Grandly scaled and richly decorated, house, better known today as Tweed code compliance can allow the Tweed Courthouse is among the most Courthouse, is architecturally one of architectural integrity and historic architecturally significant public build- New York City’s greatest civic monu- ings constructed in the United States features of a building to be preserved ments (Fig. 1). Built between 1861 and during the third quarter of the nine- without compromising life safety. 1881, it is the product of two of the teenth century. First intended to be the city’s most prominent nineteenth-cen- “New City Hall,” it has actually served tury architects, John Kellum and as county courthouse, city courthouse, Leopold Eidlitz. The courthouse is also and municipal office building. Through the legacy of Tammany Hall boss all these changes in use, the building William M. Tweed, who controlled the retained its original spatial arrange- initial construction. While notorious for ment, encompassing 30 monumental his corrupt political machine, Tweed courtrooms and a five-story central did in fact affect positive change in the rotunda within its 177,500 square feet of space (Fig. 2). The immense cast-iron structural and decorative elements in the rotunda and courtrooms are unpar- alleled in any American public building. Although the courthouse was threat- ened with demolition as late as the 1970s, its significance has been recog- nized by governmental agencies at the local, state, and national levels. In 1974 it was listed on the National Register of Historic Places and two years later designated a National Historic Land- mark by the U. S. Department of the Interior. In 1984 the New York City Landmarks Preservation Commission honored the building with exterior and interior designations.

Restoration and Rehabilitation: An Overview The restoration of the building began in 1989, when the city commissioned a Fig. 1. Tweed Courthouse, 52 Chambers Street, New York City, restored exterior. The exterior of the feasibility study for the building’s courthouse, constructed of Tuckahoe and Sheffield marbles, was completely restored. More than preservation and reuse. In 1999 Mayor 1,500 pieces of stone were repaired across the entire building facade. The entire 1,220-foot-long cor- Rudolph W. Giuliani directed the New nice, including 335 modillions, was replaced. The monumental Chambers Street stairway, which was York City Economic Development removed in the 1940s for street widening, was rebuilt as the main entrance to the building. Along with the re-establishment of the three double-doorway entrances on the main floor, the restored Corporation to proceed with a $90 stairway provides code-complying egress for the new uses of the building. Previously, the building did million comprehensive restoration of not have adequate egress and exiting. Photograph by Michael Rogol. the building. Under Mayor Michael

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that codes be applied in a flexible man- ner that addresses the intent of the code rather than its prescriptive regulations. When planning for the restoration and reuse of Tweed Courthouse began in 1989, the starting point was an analysis of its compliance with the current Building Code of the City of New York. While some deficiencies, such as the lack of fire-detection sys- tems, emergency lighting, standpipes, sprinklers, and a fire-command station, could easily be addressed during a comprehensive restoration, other inher- ent code violations were not as easy to resolve. Many existing building features and elements could not be brought into compliance with modern building codes without a complete reconfiguration of the interior, which would have resulted in the loss of the building’s historic Fig. 2. Second-floor plan. The main floor of the building, at the second story, is reached by the re- integrity. For instance, the monumental stored Chambers Street staircase. The new code-compliant fire stairs are located within former cast-iron stairways were not enclosed; service rooms. Drawing by John G. Waite Associates, Architects, PLLC. the central rotunda opened into the main corridors and stairways; the open- Bloomberg the building was fitted out Nevertheless, those responsible for its cage elevators were not located in en- in 2002-03 as the headquarters for the construction recognized the hazards of closed shafts; the elevator lobbies City’s new Department of Education. combustible building materials in a opened into the central rotunda on all The restoration of Tweed Court- dense, rapidly growing urban setting. floors; and unprotected cast- and rolled- house was a complex and intricate The courthouse is an early example of iron floor and roof framing members process. A large team of architects, entirely fire-resistant construction, were exposed in most spaces. The build- engineers, construction managers, which utilized iron in place of tradi- ing did not even have adequate code- architectural historians, archeologists, tional timber framing. The structure of compliant egress from each floor or building conservators, and contractors the building consists entirely of wrought exits to the exterior. Although following was assembled to carry out the design and cast iron with load-bearing ma- the prescriptive requirements of the and construction work. Because the sonry walls. Even the lath used in the code would, in many ways, have been work was so extensive and because plaster walls is made of iron, as are the the easiest course for the architects to there was a period of only two-and-one- concealed brackets supporting the follow, it would also have been very half years for design and construction, plaster cornices. Cast iron was used for damaging to the building and would the architects and construction manager virtually all of the decorative elements not have resulted in a safer facility. established full-time offices at the site. in the public spaces. As a result of this preliminary analy- At any one time portions of the work Construction techniques have sis, it became apparent that the key to were under construction; the architects changed substantially since Tweed an effective fire-management program were preparing drawings for other areas Courthouse was built, and building for the building, regardless of its even- of the building; and planning was un- codes have reflected those changes. tual use or occupancy, was a strategy derway for still more of the work. This Building codes establish a minimum focused on the central rotunda. The integrated approach allowed the project level of safety, particularly with respect conventional fire-safety approach would to be completed on schedule and within to fire, that must be provided for a have sectioned off the rotunda from the budget. Ultimately, there were more structure and its occupants. Today, the rest of the building by inserting rated than a hundred separate contracts and treatment of historic buildings is all too fire separations in the openings that hundreds of construction workers often adversely affected by a rigorous connected the rotunda to adjacent employed on the project. and inflexible interpretation of codes hallways and the monumental open that were developed to regulate the staircases. However, this approach would have seriously altered the historic Prescriptive Analysis of Building-Code construction of modern buildings, arrangement of the public spaces and Compliance rather than the rehabilitation of existing buildings. In order to protect the his- compromised the basic character of the Tweed Courthouse was constructed toric integrity of a building while mak- interior and many of the major architec- long before the City of New York estab- ing it safe for its users, it is essential tural features. lished a comprehensive building code. TWEED COURTHOUSE 17

Fig. 3. Restored rotunda. The key to the fire-management plan was the Fig. 4. Restored laylight. The stained- and etched-glass laylight, located restoration of the rotunda for use as a smoke reservoir. In the event of beneath the main skylight, was reconstructed in its entirety based on fire, smoke and combustion gases are collected in the upper section of dozens of fragments salvaged when the original laylight was demolished the rotunda, above and below the stained-glass laylight. The arched open- in the 1940s. The laylight forms the ceiling of the rotunda and is thus a ings at the upper level were filled in with heat-resistant glass panels. critical element in establishing the rotunda as a smoke reservoir. The Fans at the attic level extract smoke directly to the exterior, making the laylight is fabricated from heat-resistant, laminated glass so that it would connecting corridors and staircases safe egress routes. Photograph by not shatter in the event of fire. Photograph by Lily Wang. Michael Rogol.

An Alternative Approach to Code are ducted to air plenums, and smoke glass laylight was fabricated from heat- Compliance and Fire Management would be ejected through dampered resistant, laminated glass (Fig. 4). By Instead, the approach that was taken vents surrounding the base of two large extracting smoke and dangerous gases during the restoration of the building skylights located above the monumental into the upper levels of the rotunda, the treated the large central space of the staircases. Connected with a new smoke- connecting corridors and other major rotunda as an advantage, rather than a detection system and with emergency spaces were made safer in the event of a disadvantage, in managing the effects of generators located in the basement, the fire. These circulation spaces could then a fire (Fig. 3). The volume of space fans are controlled by a computer that serve as additional, effective egress above and below the decorative laylight activates them automatically when a fire routes. in the upper portion of the rotunda, just is detected. Manual control of the The basic concept of the fire-man- under the skylight, would act as a system by firefighters is possible, once agement program, centering on the smoke reservoir, collecting and exhaust- they assess the smoke and building rotunda, was developed early in the ing smoke and combustion gases from conditions upon arrival at the building. project by the architects and engineers the space. Central to the success of the Also, one of the fans is redundant, and outlined in preliminary meetings rotunda as a smoke reservoir was the functioning as a standby in case of with officials at the New York City installation of four large fans at the equipment failure. Department of Buildings. Approval of attic level, which would extract smoke In order to make the upper section of the overall approach, which was from the top of the rotunda. These fans the rotunda an effective collector of granted by the Department of Buildings are visible only from within the attic smoke, the arched masonry openings on in 1990, was necessary because the and not from any level of the rotunda the fourth floor were filled in with heat- lobbies of the historic 1911 open-cage or from the occupied floors. The fans resistant glass panels, and the stained- passenger elevators, which were sched- 18 APT BULLETIN uled for restoration as the first phase of concrete topping slab poured above the the larger, comprehensive project, did vaulted floor construction. In the vast not meet modern code requirements. rotunda infrared beams are used for Approval of the basic concepts of the early smoke detection. This beam- fire-management program, in particular detection system also minimizes the the plans for a smoke-extract system visual impact of the system in this for the rotunda and for interconnected space. In the large, interconnected spaces such as the elevator lobbies, spaces of the south wing, designed by meant that work on the open-cage ele- Leopold Eidlitz, an air-sampling system vators could proceed while planning for was installed to continually monitor air the other aspects of the restoration and within the rooms to detect products of reuse of the building was underway. combustion, as well as smoke (Fig. 5). Flexible plastic tube piping was laid Evaluation of a Comprehensive Fire underneath areas of new decorative Strategy Using Performance-Based floor tile and connected to monitoring Engineering tanks located in the basement and attic. The intakes for this system are incorpo- In 1999 the fire strategy for the entire rated into the historic gas-lighting building was tested by ARUP, a fire- fixtures within the spaces. Because of engineering consultant to the architect, their location and small size, they are with computer-simulation studies. The virtually unnoticeable. simulations of the performance of the Prior to detailed presentations to and existing building analyzed various fire conversations with the fire department, scenarios with different building-user a series of acoustical tests was con- populations, combustion locations, fire Fig. 5. Restored courtroom in the south wing. ducted within the rotunda, major corri- This courtroom, designed by Leopold Eidlitz, intensities, and fuel loads. The develop- dors, and large rooms. These tests ment, size, and behavior of smoke has tile floors and polychromed-brick jack-vault ceilings. The bottom flanges of the rolled-iron measured the acoustic performance of plumes was modeled using computa- beams supporting the jack vaults are exposed. the various spatial configurations, as tional fluid dynamics analysis, and The reproduction chandeliers provide the well as of the plaster, marble, and cast- human-behavior studies were incorpo- principal illumination for the room, using frosted iron surfaces and their respective audi- tungsten halogen lamps. The historic fixtures rated into timed-egress studies, which bility and intelligibility levels. These graphically show the exiting patterns also serve as emergency lighting throughout most of the building; they are wired to emer- tests were critical in determining the and times required for people to evacu- gency circuits that are activated by the fire- and type, quantity, and placement of horn ate the building, given each hypothetical smoke-detection system. This arrangement and strobe-alarm notification devices situation. The age, mobility, and num- alleviates the need for modern emergency- within the historic interiors. The acous- lighting fixtures, which would be visually intru- ber of occupants were adjusted in the tic demonstrations, especially within the computer program to provide the most sive in the historic spaces. Because the detec- tor heads for the air-sampling smoke-detection five-story rotunda space (Fig. 6), also comprehensive analysis possible. Car- system are incorporated into the lighting fix- supported the fire department’s decision ried out with the active participation of tures, they are not visible in the room. Photo- to approve a fire-alarm system that the New York City Department of graph by Lily Wang. notifies all occupants of the courthouse Buildings and the Fire Department of simultaneously, instead of only in zones New York, these timed-egress studies and life safety. As part of this program, as the building code stipulates for large, were among the first done for a historic a sophisticated, interconnected smoke- modern, high-rise buildings. building in New York City. These per- detection and fire-alarm system was formance-based engineering studies, installed throughout the building. The Fire-Protection Systems which can model, measure, and quan- installation of some of the detectors for tify the performance and effectiveness this system required innovative tech- Following an analysis of the perfor- of alternate solutions to the prescriptive niques to allow them to be effective yet mance of various structural members requirements of conventional codes, inconspicuous within the historic when exposed to fire, it was determined hold a great deal of promise in restoring spaces. Monitored at the fire-command that sprinklers were not required in any and rehabilitating historic structures, so center within the building and remotely of the historic courtrooms, corridors, or that they are made safe without de- by the fire department, this system pro- other public spaces. Sprinklers were stroying their distinctive character. vides early detection of heat or smoke installed, however, throughout spaces conditions related to a fire. In most of that are not connected with the rotunda Detection and Notification Systems the spaces conventional smoke and smoke reservoir. They were located in the basement, first and fourth floors, The fire-management program included, ionization detectors were installed at the ceilings and energized through and in confined areas of the attic (Fig. and integrated into a coherent whole, 7). These areas, most of which have low all aspects of the building relating to fire conduit buried in the new lightweight TWEED COURTHOUSE 19

Fig. 6. Cross section looking south. This section shows how the central rotunda is open to the main corridors and monumental staircases. By using the rotunda as a smoke reservoir, the historic, open character of the space was preserved. The four large fans, which extract smoke and gases from the ro- tunda, are located in the attic and are not visible from the rotunda or connecting public spaces. The fans, one of which is redundant and on standby in case of equipment failure, are controlled by the building-management system and are activated by the new fire-detection and alarm systems. Drawing by John G. Waite Associates, Architects, PLLC. ceilings, were more likely to contain reconnected in front of Tweed Court- fabricated from both wrought- and combustible materials because of their house at Chambers Street. This repair, cast-iron components. Analytical efforts projected occupancies. Standpipe risers which required careful monitoring were focused on the major support were located within the new fire-stair because of the archeological sensitivity elements that would trigger larger struc- enclosures, as well as in the passenger- of downtown Manhattan, restored the tural failures if locally compromised by elevator lobby off the rotunda. Fire- integrity of this segment of the city’s fire; these columns and trusses were department siamese connections to underground water-supply grid while protected with intumescent paint. The supply the standpipes were installed in providing two independent sources of new roof assembly incorporated a fire- three locations around the exterior of water for the fire-suppression system retardant underlayment installed over the building and stand free from the within the building. Additionally, a metal decking, which further protects granite base of the marble facade. The new fire hydrant was installed at the critical structural members of the roof fire department considered it a benefit relocated curb edge of the street. system. that the building is located within a The original unprotected metal public park, thus permitting access to framing of the building, which con- Emergency Systems the entire perimeter of the building by sists of cast-iron columns, the bottom fire apparatus. Increased access to the flanges of the rolled-iron floor beams, To provide illumination in the event of building means more options for fire and rolled-iron trusses, was also ana- emergency, a new emergency-lighting suppression and management and, lyzed. Rather than encasing the mem- system was installed throughout the therefore, a safer building. bers in conventional concrete or plas- building. Instead of visually intrusive The standpipe and sprinkler systems ter fireproofing, it was decided to battery-pack lights, many of the historic were planned to accommodate future protect critical structural members by chandeliers and wall sconces were wired expansion and distribution capabilities using intumescent paint, which expands to emergency panels. The emergency within the building, and a fire pump to form a protective layer when sub- panels are energized by two diesel was installed in anticipation of extend- jected to high temperatures. On most generators located in an exterior, below- ing the system to provide protection of the floors, however, the wrought- grade vault connected to the basement; within the wood-framed attic of City iron beam flanges were already effec- these generators power all the life-safety Hall, which is less than 100 feet away. tively protected by the original ceilings, systems located within the courthouse In order to provide adequate water which consist of plaster on corrugated and all the power requirements within pressure for both of these systems, an iron lath. City Hall. A fuel-storage room, located eighteenth-century water main, which Much study was given to the struc- in the basement, adjacent to the genera- had ruptured long ago and had been tural performance of the roof framing tors, is protected with three-hour-rated abandoned by the city, was repaired and members, many of which had been construction. Even though construction 20 APT BULLETIN

Fig. 7. Sprinkler studies. As part of the computer-simulation studies undertaken by ARUP, the fire-engineering consultant to John G. Waite Associates, Architects, the need for sprinklers was evaluated. Based on these studies, it was determined that only the basement, first and fourth floors, and attic spaces needed to have sprinklers in order to be safe for the building’s new uses. These areas are not directly connected with the central rotunda. Drawing by ARUP for John G. Waite Associates, Architects, PLLC. work at the courthouse was still under- Timed-Egress Simulations and Exiting The keys to providing additional way on September 11, 2001, the two Capacities exiting for the restored building were emergency generators were already in the rebuilding of the original monumen- Another critical component of the fire- service. Because of these generators, tal staircase at the Chambers Street safety strategy was providing sufficient Tweed Courthouse and City Hall were entrance and the restoration of the three fire exits from the building to the exte- among the few buildings below Canal original double doorways at the main- rior. Because a smoke-management Street that had electrical power and floor level. In the 1940s, as a result of system was to be installed, the two therefore could be used by emergency increased vehicular traffic and the re- original, freestanding cast-iron stair- workers and government officials in the duced use of the courthouse, the exte- ways, located adjacent to the rotunda, aftermath of the attack. rior masonry staircase at the Chamber did not require fire-rated enclosures. Tweed Courthouse was used by the Street entrance was truncated, and the Instead, they were restored and left fire department as an emergency facility remaining portion of the staircase was open to the corridors and rotunda (Fig. for firefighters working at the World covered over with concrete slab con- 8). Two new steel-and-concrete fire Trade Center site. It is worth noting struction. In 2000 the city approved stairs were constructed, one at each end that on September 11, Tweed Court- plans to narrow Chambers Street, re- of the building, in spaces previously house was protected not only by mod- move a lane of traffic, and reorganize occupied by service rooms. Fully en- ern, state-of-the art fire detection and the flow of traffic. This scheme allowed closed, these 5-foot-wide stairs exceed protection systems but also with mid- the courthouse’s primary entrance to be the code-mandated width of 3 feet 8 nineteenth-century fire-protection mea- reconstructed. inches; they serve all floors including sures. Just before vacating the building The rebuilding of this monumental the attic and basement and exit directly on the morning of September 11, the staircase, the restoration of the front to the exterior. The new stairways are architects and contractors closed the entrance lobby space within the build- suspended from the roof framing by original iron window shutters, which ing, and the restoration of the three steel rods and do not touch the 2-foot- had just been restored to operable original double doorways at the main thick masonry bearing walls, thus pre- condition, to protect the interior from floor level provided additional exiting serving the original plaster wall finishes damage, should the exterior windows for the building that exceeded the code and cast-iron architectural trim of the break. The windows did not break but requirements. The restored exterior service rooms. In the future the rooms the stone facades suffered smoke dam- staircase was essential in providing the could be restored to their original con- age which required exterior cleaning required egress for the building and also ditions if the stairs were removed and again. critical in reestablishing the original new floors were inserted. character of the building. TWEED COURTHOUSE 21

Compartmentation and Smoke- Conclusion Development Studies The custom fire management program Most building materials within Tweed for the Tweed Courthouse demonstrates Courthouse — stone, brick, and cast that a historic building can be made iron — have an intrinsic fire resistance safe without compromising its historic that greatly aids the containment of integrity if the fire risks, and resulting smoke or fire within a given space. As building performance, are carefully part of the fire-safety strategy, especially analyzed and if a comprehensive strat- with regard to the smoke-management egy is developed to address those risks system, the historic courtrooms needed as part of the restoration program. This to be separated with fire-rated construc- approach requires the utilization of tion from the circulation spaces and state-of-the art technologies and proce- central rotunda. This compartmental- dures, creative architectural and engi- ization was inherent in the bearing-wall neering solutions that are individually construction but could be compromised tailored to the specific building or con- by the heavy wood and decorative dition, and the participation and coop- etched-glass entrance doors to each eration of building-code and fire-service room. Computer-modeling simulations officials throughout the process. demonstrating smoke and heat develop- ment examined the behavior of various JOHN G. WAITE, FAIA, is senior principal of John G. Waite Associates, Architects. The firm fire scenarios within in a typical room. was the architect for the restoration and reuse The results indicated that in an intense of Tweed Courthouse. Currently, the firm is fire situation, the heat produced would writing a book, entitled Tweed Courthouse, a most likely cause the glass of the large Model Restoration, to be published by W. W. Norton & Co. in early 2005. exterior windows to break, allowing the buildup of smoke to vent first to the NANCY A. RANKIN is an associate of the firm exterior, rather than throughout the and was project manager for the Tweed Court- interior of the building. To add an extra house project. level of safety, the wood doors were restored; magnetic hold-open door catches connected to the fire alarm system were installed; and the original etched-glass panels were removed at the request of the Department of Buildings and replaced with a technically ad- vanced ceramic. The original etched- glass panels were used by the door restoration contractor to duplicate the appearance and exact pattern onto each individual replacement piece of glazing. 1 This ⁄4-inch-thick material, which can withstand temperatures of 1200° F, is laminated, providing an extra measure of safety. This material was developed Fig. 8. Fire-simulation studies. Computer- for use in the space exploration pro- simulation studies analyzed different scenarios with varying building-user populations, combus- gram and has only recently been made tion locations, fire intensities, and fuel loads. available for architectural installations. The studies graphically depicted the develop- In the event of a fire in one of these ment, size, and behavior of smoke plumes and spaces, the door assemblies would have heat, as well as the exiting patterns and time a performance fire rating equivalent to required for people of different ages and levels of mobility to vacate the building. These plans one hour, as required by prescriptive show how people dispersed throughout the codes. building proceed to exits within 10, 30, and 120 seconds. The plans also show the performance of one of the new fire stairs as part of the exiting process. These studies helped to con- firm the concept of using the rotunda as a smoke reservoir. Drawing by ARUP for John G. Waite Associates, Architects, PLLC.