Order Restored

A New York City courthouse with a dark past gets a bright future thanks to this Building Team's innovative restoration effort
August 11, 2010

At the time of its construction in the mid-19th century, Tweed Courthouse was at the center of political corruption in New York City.

The project's lead city official, local politician William "Boss" Tweed, was the elected leader of Tammany Hall, a corrupt political club that slowly took control of the local Democratic Party, and, in turn, seized control of the city government. The organization had a history of profiting from city business by taking bribes, giving city contracts to members, and stealing funds from the city treasury. Tweed took Tammany's corruption to a new level during construction of the courthouse, which would become his final and most controversial heist.

Tweed purposely inflated construction costs to a then-astonishing $13 million — nearly twice as much as the purchase of Alaska in 1867 — and received hefty kickbacks from contractors. The cronyism was blatant — a carpenter was reportedly paid $360,000 for one month's labor in a building with little woodwork; a furniture contractor received $179,000 for three tables and 40 chairs.

Tweed also purchased the stone masonry from a quarry owned by one of his close associates. He even profited from a city investigation into why it took so long to build the courthouse — Tweed's printing company printed the committee's report.

Tweed's chicanery eventually led to his arrest in 1871. He was convicted and died penniless in prison. It would be another decade before the building would be completed.

While the lore of Boss Tweed's dirty deeds has faded through the years, the courthouse that helped to end his corrupt political reign still stands magnificently next to City Hall in lower Manhattan, thanks to a $107.8 million restoration effort.

The four-year project involved restoring the building's interior and exterior historic features, bringing the building up to modern code standards, and converting the facility into offices for the city's Department of Education. The Building Team's innovative solutions to challenges and careful attention to detail earned it a Grand Award in Building Design & Construction's 20th Annual Reconstruction Awards.

Designed by two of New York's most prominent architects of the 19th century, John Kellum and Leopold Eidlitz, the five-story, 177,700-sq.-ft. building features a full-height central rotunda with two projecting wings that house 30 courtrooms.

The building was threatened with destruction several times between 1903 and 1974, when it received historic landmark designation from the New York Landmarks Preservation Commission.

"It's unusual to have both the interior and exterior designated as landmarks," says Jack Waite, principal of architect John G. Waite Associates, Architects. The Building Team had to work closely with the landmarks commission to ensure the building's historic integrity was not undone.

Performance-based compliance

Most crucial was bringing interior spaces up to modern code, especially with regard to HVAC and fire- and life-safety systems.

"It was readily apparent that if we applied the city building code to that building, we would really cause major damage to its historic integrity," says Waite. "So the city agreed to work with us to develop a performance-based code compliance."

M/E engineer ARUP worked with city building officials and the fire marshal to devise a performance-based design for fire protection. Under the existing building code, the central rotunda would have had to be completely closed off from the offices. Instead, ARUP used the rotunda as a smoke reservoir. In case of fire, four computer-driven fans installed near the rotunda skylight would pull smoke out of the offices and corridors into the rotunda, then vent it out of the building.

"By considering realistic fire hazards, occupant behavior characteristics, and the inherent fire-protection features of the courthouse, we were able to limit the use of architecturally intrusive active fire-protection systems without compromising life safety," says Imtiaz Mulla, project manager formerly with ARUP (now with Meinhardt USA, New York).

For instance, he says the smoke reservoir concept eliminated the need for sprinklers in the rotunda. And by using the grand stairway in the rotunda for egress, the Building Team was able to justify installing only two fire stairs, instead of the four required by the code.

As for the HVAC system, ARUP utilized more than 200 existing masonry ventilation shafts to run flexible ducts for a forced air-distribution system. The firm conducted air-speed and temperature-gradient studies using computational fluid dynamics analyses, which showed that conditions could be maintained with high-level supply and low-level return using historic grilles and constant airflow, says Mulla.

This approach not only reduced costs, but also protected the historic integrity of the interior spaces, says Waite. "To install ducts throughout the building would have required suspended ceilings covering the existing ornamental vaulted ceilings," he says.

All air-handling equipment was installed in the basement and attic spaces, previously used for furniture storage.

In the office spaces (once the courtrooms), the Building Team specified a 2 3/4-in. raised-floor system for distribution of electric and communications cable.

Falling façade

Years of exposure to the harsh weather and lack of maintenance took a toll on the stone façade.

Most badly damaged were massive marble cornice moldings that extend four feet out at roof level from the top of the building's 900-ft. running perimeter. Portions of the double-layered cornice had deteriorated so badly that parts of the property had to be fenced off and temporary shoring towers erected.

Instead of repairing the individual cornice stones, the Building Team decided to cut off the entire cornice — 2.5 million pounds worth of stone — and replace it with new Cherokee marble, quarried in Tate, Ga.

Structural engineer Robert Silman Associates, New York, employed a novel technique for supporting the replacement marble cornice. They inserted 1,800 six-foot-long stainless-steel threaded anchor screws five feet into pre-drilled holes in the building's existing back-up stone. Each cornice piece — weighing about 3,500 pounds — is supported by five anchor screws, which were grouted into the back-up stone.

Although the steel anchoring system may have been a rather high-tech method for supporting the cornice pieces, it was actually less complicated than more traditional techniques. "Originally, we were going to take away all that mass and pour concrete in its place, which would have been a more complex system structurally," says Waite.

The new cornice pieces were laser cut from blocks and hauled from Georgia in 45,000-pound shipments. In all, four million pounds of new stone were required to replace the cornice and fix other damaged façade elements, such as the projecting windowsills and heads.

Replacement elements were hand cut from the old cornice stones, as well as from 125 untouched blocks that were found at the original quarry in Sheffield, Mass., which also supplied stones for the Washington Monument.

"Literally, the day the Tweed Ring was exposed, the government cancelled the contract with the quarry for the Washington Monument," Waite says. "So there were all these stones that were half out of the ground that had been cut for the monument. The workmen must have just dropped their tools and left them."

Other special details, including missing ornate stone leaves that once adorned the capitals of the building's columns, were hand-carved on site. "These leaves started to fall off sometime in the 1940s, so the city maintenance people went up there and chipped them all away," says Waite. Craftsmen hand carved new leaves on site and pinned and glued them in place.

The grand entrance stairway on the north side of the building, which had been removed in 1944 for the widening of Chambers Street, was rebuilt with the addition of 17 new Vermont granite steps.

Final price tag for the stonework was $16 million, making it one of the largest stone façade restoration jobs in the U.S. at the time, says Waite.

Re-creating a cast-iron roof

The courthouse's original tin-coated, corrugated cast-iron roof had rusted away years ago. That left the team with nothing but scrap pieces of the original roof from which to work. They re-created the roof with a two-part system — 22-gauge tin-coated stainless-steel corrugated panels over an EPDM system — installed on the existing iron trusses, which were found to be structurally sound.

Because it was determined that the roof could not be worked on in sections, a temporary roof spanning 75,000 sq. ft. had to be erected. The roof was supported by a custom, four-pole scaffolding system design by Atlantic Scaffold, Maspeth, N.Y. It completely covered the building and the scaffolding that surrounded the perimeter, guarding the stone façade work from the weather. Moreover, the scaffolding was engineered to support the weight of the replacement stones, which average about 3,500 pounds.

"To be able to accomplish what we did for the amount of money and time we had allocated was very satisfying," says Melvin A. Glickman, executive VP with owner's representative New York City Economic Development Corporation. "It was a job where everybody was proud to work on the project. I tell everybody that I would have worked on this job for no salary at all."

         
 

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