Faulty Towers

When bricks peeled off the side of 540 Madison Avenue and tumbled to the pavement last December, the office tower was portrayed in the press as an architectural Bad Seed, a building destined to wreak havoc from the moment it was born. Though the southern façade of 540 Madison gave way only after workers hired by the new owner, Harry Macklowe, punched windows into a previously unbroken expanse of brick, blame was heaped on the negligence of the contractors who erected the tower in the late sixties. They had left out two thirds of what should’ve been 14,500 brick ties, strips of corrugated metal that anchor the thin brick exterior wall to the layer of cinder block that sits snugly on the building’s frame.

Certainly, 540 Madison represents a worst-case scenario, but its troubles are not unique. The building’s deficiencies are rooted in the fact that modern architecture allows only a thin margin of error. Our faith in structural engineering and computer simulations has led to a “lack of redundancy.” That’s the phrase used by architectural engineers Matthys P. Levy and the late Mario Salvadori in their book Why Buildings Fall Down to explain disasters such as the 1979 collapse of the Kemper Arena in Kansas City, triggered by rain, wind, and miscalculation.

Generally, when we think of buildings being dangerous, we think of old ones, all covered with parapets, balustrades, and gargoyles. But many of these structures are in fact much stronger than newer ones. Structural engineer Donald Friedman, author of Historical Building Construction, tells a story about working on a 1917 office building in lower Manhattan that was supported by steel columns clad in brick. “We opened up a column, and there was no column there,” Friedman recalls. “There was a hollow space in the brick pier in the shape of the column, and a little red staining on the brick where there was rust. But the column was gone. It had rusted to the point where it was gone. For four stories, from the roof down, there was no column worth talking about.” But because the old building had twelve-inch-thick walls, it didn’t fall down. That’s redundancy. Modern buildings don’t work that way.

Five forty Madison uses brick the same way it uses glass, as a veneer that bears no load. Picture it: a wall 39 stories tall but only one brick thick. What keeps the skinny wall standing is its connection to the frame of the building. But that connection is remarkably tenuous: a strip of corrugated steel one tenth of an inch thick and perhaps eight inches long – the construction-industry equivalent of those plastic ties that come with jumbo trash bags – planted in the wall every four square feet of brick. If the contractor skimps on brick ties, all bets are off. Most modern architecture depends, if not on brick ties, then on bolts, or steel angles, little pieces of hardware.

About a month before the bricks began tumbling on Madison Avenue, the Whitney Museum finished reinstalling the 1,500 six-hundred-pound granite slabs that make up its façade. The Whitney, a sleek powerhouse of a building, was a mess behind the granite. Architect Marcel Breuer made one bold statement, but the building’s original contractors apparently built it with whatever metal fasteners they could find: “When we took off the skin here,” says the project’s restoration architect, Diane Kaese of Wiss, Janney, Elstner Associates, “we found galvanized steel, we found brass, we found stainless steel, we found regular carbon steel. We found painted steel. We found unpainted steel. You name it, we found it. It was crazy. It was wacko.”

The problem that afflicted both the Whitney and 540 Madison – inadequate or improper anchoring of the façade – is commonplace. Every structural engineer or restoration architect, it seems, has an anecdote. Some of the scarier stories involve marble, an opulent material that suggests permanence but is actually quite brittle when it’s sliced an inch or two thin, as it is on many contemporary buildings. In Chicago, the owners of the 82-story Amoco Building waged a decade-long battle to keep the slabs of Carrara marble, weakened by humidity and pollution, from slipping right off the side of the building. Finally, they gave up and re-sheathed the tower in granite. Meanwhile, at the General Motors Building on Fifth Avenue, the owners have instituted an “Ongoing Marble Panel Repair Program” to secure or replace marble slabs, which, according to building-inspection reports, fall apart on a regular basis.

“Marble is not a good material, especially in an atmosphere like New York, where you have high acidity in the air,” notes Matthys Levy. ”It doesn’t do that well in Rome, either.”

Landmark towers may not be immune to failure, but boring, ubiquitous buildings, the ones we take for granted, often cause the most trouble. Before 540 Madison came along, one of the most troubled buildings in New York was the Vermeer, a 1964 co-op at Seventh Avenue and 14th Street. Six years ago, its original layer of white glazed brick had to be completely removed and replaced. Though nothing tumbled to the street, the façade was bulging conspicuously. The reason is that the concrete that forms the building’s frame tends to shrink, while brick walls remain constant. Restoration architect Walter Melvin discovered that the steel angles that were supposed to support the brick wall and lock it to the frame had either shifted, because of the shrinkage, or were missing altogether. This meant that the brick wall was only loosely attached to the building and was beginning to crumble under its own weight, crushing the ground-level storefronts. Architects and engineers say this is a very common situation for buildings of this era.

“We’re just working through every building built in New York in that time period,” says Melvin. “There are no movement joints whatsoever in the buildings. The concrete frames shrink, crushing the brick on the outside and disconnecting the wedge anchors that hold the brick shelves on the side of the building. And then they had the problem where they didn’t have enough anchors in anyway. Every one that I’ve opened up has had too few anchors.” So if you look carefully at any glazed-brick building surrounded by a sidewalk shed – and there are plenty of them – you will see bulging spots, cracks, and, occasionally, sections of the siding pulling away from the façade.

Here’s an unsettling idea: Besides the fact that a shoddy construction job or a poorly thought-out design can sit quietly for decades and then one day, like a volcano, erupt, our knowledge about the design and construction of buildings isn’t cumulative. We don’t exactly learn from our mistakes, because the technology keeps changing.

Buildings, especially in the postwar era, especially signature skyscrapers, are experiments, one-offs. While the brick-and-tie method of building is positively anachronistic – colonial architecture in the sky – more technologically assertive methods of building design and construction are also problematic. Signature buildings of every decade have pushed the envelope of engineering knowledge and construction techniques, and the most elaborate designs can be undone by very small things. As the space-shuttle Challenger explosion could be pinned on faulty O-rings, problems with big glass office towers can often be attributed to sealants. Glass office towers, mighty statements of corporate and architectural power, have to be caulked, like bathtubs, or they’ll leak.

“It’s the archenemy, water,” says Kaese.

“Water is the single most destructive thing, even sitting there doing nothing, just being water,” adds architect Page Ayres Cowley of the Cowley Duenow Partnership.

Water proved to be the undoing of one of New York’s most significant architectural landmarks. Lever House, the 1953 Skidmore, Owings and Merrill building, began the city’s romance with the glass-curtain wall. “The architects’ design was to make it almost a prism, so that it almost floats,” notes Alex Herrera, director of preservation at the city’s Landmarks Preservation Commission. “They designed it with the best technology they had available at the time.”

Unfortunately, while the building has gleaming stainless steel framing the glass on the exterior, the steel inside, the lattice that actually supports the glass, was not stainless. And because the sealants, made of a linseed-oil-based putty – state-of-the-art, 1953 – failed, the steel structure of the curtain wall rusted. The rust caused the steel to expand, dislodging or breaking many of the building’s glass panels. For years, maintenance crews replaced glass panels whenever they broke. SOM has devised a plan to rescue Lever House that involves re-skinning the whole building and replacing the rusty steel with stainless.

The architects and engineers who inspect façades for structural flaws are like the oncologists of the building trades, telling us things we don’t really want to hear. Kaese, who is currently finishing up the restoration of the Whitney Museum’s façade, mentions a trait of the World Trade Center’s that is less overtly frightening but still unnerving: “If you sit on the east side in the morning when the sun hits the building,” she says, “you can hear the whole thing pop. You can hear the movement of the structure.”

She then points out that this is true of any building “if it’s quiet enough.” Buildings, like people, harbor little idiosyncrasies and pathologies that occasionally cause them to behave destructively, dumping a ton of bricks onto Madison Avenue during peak holiday-shopping season, say, or caving in on 42nd Street just as New Year’s Eve approaches. And rainy spells bring out the worst in buildings. This winter’s parade of northeasters has turned some masonry façades into cottage cheese.

Friedman, for his part, is marginally reassuring. “Nothing collapses,” he says, “until a lot of things are wrong simultaneously. It takes a lot for brick to actually start falling off a building.”

And if that is not comforting enough, Friedman adds that a building on the verge of collapse will likely issue some sort of warning. “Before everything falls down, there are a lot of ugly noises,” he says. “There’ll be a rain of mortar before the bricks themselves actually start falling out, so it’s like, ‘Why am I getting pelted by sand?’ That would be your first reaction.”

And your second reaction? What should you do if you’re walking down the street and you feel a trickle of sand falling on your head?

Friedman, the structural engineer, offers a pragmatic answer: “Run.”

Faulty Towers