Tradition restored

Historic slate roof of one of New York's oldest synagogues is rebuilt after devastating fire
August 11, 2010

Aug. 28, 1998, was a tragic day for the congregation of Manhattan's Central Synagogue, one of New York City's oldest Jewish temples. A fire — ironically started accidentally by a worker repairing a rooftop air-conditioning unit — quickly engulfed the building's roof and spread downward. It destroyed the gabled roof and severely damaged much of the interior of the 25,000-sq.-ft. temple, which was designed in 1874 by Prussian-born Jewish architect Henry Fernbach.

Three years and $40 million later, Central Synagogue has been restored to its original grandeur. A private venture funded mostly by the synagogue's 4,000 congregates, the project was organized by the Central Synagogue Building Committee, led by Rabbi Peter Rubenstein. The committee commissioned New York City-based architect Hardy Holzman Pfeiffer Associates (HHPA) to design the restoration. Other team members included structural engineer LZA Technology, a division of New York City-based The Thornton-Tomasetti Group; Philadelphia-based restoration architect Dan Peter Kopple & Associates (DPK&A); and general contractor Dajon Associates Inc. of Hackensack, N.J.

"There was virtually nothing salvageable from the clerestory level up," says Jonathan Schloss, project manager with HHPA. "The entire roof collapsed, piercing through the sanctuary floor below."

With the building fully exposed to the weather, top priority was erecting a temporary roof. Mount Vernon, N.Y.-based Universal Builders Supply Inc. designed a custom scaffolding system with a EPDM roof membrane. Once in place, the building team moved forward with reconstruction of the roof, which was fast-tracked because it had to be completed before work inside could begin.

Wood vs. steel

"It was debated long and hard whether to use steel or wood for the new roof trusses, which were very comparable cost-wise," says Carl Doebley, project manager with DPK&A.

Although steel is structurally stronger, Doebley says the team chose to replace the trusses using wood for several reasons: "First off, wood beams behave so well during fires. Incredibly, only one of the seven original wood trusses failed during the fire," he says. "It shows the wonder of heavy timber — 12-in.-sq. wood beams can hold up better than unprotected steel beams.

"Also, introducing rigid steel supports over a wooden and cast-iron structure can be complicated, because the two materials expand and contract differently," he says. "It just seemed more appropriate to reintroduce a similar material so that the building can move in unison." Composed of Douglas fir, the wood trusses span 35 feet.

Doebley understands the challenges of introducing steel in a wood structure. DPK&A is currently using steel beams to reinforce the roof of a 1830s wood-framed church in Philadelphia. "In that project, the wood trusses failed, so we're inserting two steel trusses perpendicular to the existing heavy timber trusses to provide intermediate support. The issues there involve designing slip joints to allow for the differential movement between the steel and the wood."

Schloss says the building team also debated during the design development phase whether to replace the synagogue's original slate roof or to construct a new standing-seam metal roof. "We knew from photographs that the Central Synagogue was originally covered with a slate roof," says Schloss. "It had been replaced with a standing-seam, lead-coated copper roof in the late 1940s. We chose to reconstruct the slate roof, which is now more prominently visible from the street."

Doebley says constructing the slate roof was actually cheaper than the metal roof because "at the time in New York City there was such a great demand for metal work and the cost for metal was high."

Old look, new materials

"The new slate roof is identical visually to the original 1872 version," says Doebley, "but with modern materials and techniques." Instead of being laid over 1-in.-thick tongue-and-groove pinewood, composite-board plywood and a vapor barrier lie beneath the slate. "Today, slate roofs are actually two roofs: the slate with a membrane below," he adds.

The firm utilized World War II military surveillance photographs of midtown Manhattan to recreate the pattern of the slate roof. The original color scheme, consisting of New York red and Pennsylvania black slate, was identified based on fragments of slate found in the synagogue's walls during demolition. More than 30,000 slate shingles were required to cover the 140-by-99-ft. roof.

Steel-formed crenellations that once ran along the roof and around the twin, 122-ft.-tall minaret towers that flank the main entrance have also been replaced with modern materials.

"In 1994, we were contracted to restore those towers as part of an exterior restoration to the building," says Doebley. "At that point, we couldn't restore the towers to 100 percent accuracy because of budget constraints, so the decision was made to create a simplified version of the original. On this project, we were able to go back to readjust the towers and brought back, for example, the ornate crenellations. Again, visually, they look similar to the original version." Instead of using galvanized steel, which would be very costly, says Doebley, fiberglass was used to restore the crenellations that circle the onion-shape domes that top the towers, while cast stone was utilized below, around the perimeter of the lower parapet.

Moreover, 23-carat gold leaf was applied to the decorative bands of the domes, as well as the finials and ribs of the towers. Smaller finials that crown the adjacent stair towers, which were removed in the 1920s, were reconstructed using copper and topped with gilded stars. "The copper will weather over time to match the onion domes," adds Schloss.

Tarred over in the late 1940s to prevent leaking, a skylight on the west side of the roof was replaced. Below the new skylight, three 6-ft.-sq. stained-glass laylight windows were restored. The windows deliver daylight to the altar, called a bema. "The effect the skylights have on the interior is incredible as colored light now dribbles onto the bema," adds Doebley.

Similarly, 12 double-story, stained-glass windows, each with a clerestory roundel, provide natural light from the upper portion of the north and south sides of the building. "All of these clerestory windows were destroyed during the fire," says Schloss. "However, enough historic glass was salvaged to reconstruct two windows, with the remainder replaced with new glass based on the original design."

Meeting the modern code and comfort requirements was also a challenge, says Doebley. For example, to provide adequate fresh air to the interior space, five new air-intake ventilators were installed on the roof.

"Obviously, today's make-up air requirements are a lot greater than they were in the 19th century," says Doebley. "So HHPA designed auxiliary ventilators to meet modern HVAC requirements. They're located on the north side of the roof, which faces a courtyard, so they cannot be seen from the street. We also recreated three lead-coated copper, Victorian-style ventilators along the top of the roof that had been removed long ago."

Doebley credits the collaboration of the entire team for the success of the project. "Within three years, almost to the day, Central Synagogue was rededicated," he says. "That is an extremely fast timetable to perform stabilization, salvage, design and construction. It involved a lot of construction while we were still designing."

         
 

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