High on the walls of an apartment tower in Manhattan, a six-foot-tall statue of a lion is cracking up. “When terra cotta fails, it fails catastrophically,” says Eric Vonderhyde, a principal at Bertolini Architectural Works.
Woodstock Tower, at 320 East 42nd Street in the Tudor City Historic District, is covered with roughly 20,000 individual pieces of decorative terra cotta – including lions, gargoyles, and gothic arches – all glazed in gray to resemble carved limestone. A significant number of those details – as many as 20 to 30 percent – may eventually need to be replaced. Simply repairing cracks in the terra cotta has worked for years, but it may no longer be enough.
“We used to do repairs, and they would last for a long time,” says Oswald Bertolini, a principal at the architectural firm, but now the Department of Buildings is less likely to accept patch repairs, so “there is pressure from the city to do repairs that are more lasting.”
Built 1929, Woodstock Tower is one of 13 apartment buildings created by the famed architect and developer Fred F. French at his Tudor City complex in the Murray Hill neighborhood. The brick tower is clad in broad limestone blocks close to the sidewalk. Higher up, its dark bricks are ornamented with hundreds of terra-cotta details, clay that was shaped in a mold, then dried, glazed, and fired in a kiln. (Some terra cotta is fired without glazing.)
“Terra cotta is a really great decorative material, much lighter than real stone and a lot cheaper,” says Vonderhyde. With a heavy coating of glaze, Woodstock Tower’s terra-cotta lions and gargoyles were almost impervious for many years to rain and weather. “Glazing,” Vonderhyde says, “is a very dense surface.”
However, since the building opened 90 years ago, much of the glazing has worn. That allowed water to soak the terra cotta, and in cold weather, the water froze and expanded, cracking the ornaments.
Every five years, experts inspect the facade at Woodstock Tower to comply with New York City’s Local Law 11 and certify that no part of the building is in danger of falling to the sidewalk or street. Experts examine thousands of ornaments through binoculars. The most recent report was filed in February 2017.
“We were surprised by the damage,” says Bertolini. Ornaments like the terra-cotta lion high up on the building show cracks probably caused by water intrusion. Waterproof patches could cover many of the cracks, but for terra-cotta pieces with worn glazing, water will quite likely seep into the piece again and make new cracks.
“The Landmarks Preservation Commission feels replacing the ornaments with materials other than terra cotta alters the feel of the building,” says Vonderhyde. “We are going to see more and more wholesale replacement. Very few materials get 80 or 100 years of life.”
Bertolini is helping the building’s co-op board plan to preserve this historic landmark and keep it in compliance with local laws. The firm has identified numerous terra-cotta ornaments that should be replaced before the next round of Local Law 11 inspections, due in 2022.
The work is expected to be costly and time-consuming. One reason is that there are only two factories left in the United States that create the kind of terra-cotta ornaments used at Woodstock Tower. As the co-op board sets its budget for the work, it needs to consider that once workers get close to the ornaments, they may find more damage that the inspectors could not see through binoculars.
For this reason, Vonderhyde says, “we advocate for a robust contingency budget of 30 percent or 40 percent of the total budget – but typically get about 20 to 25 percent.”