This week will mark 10 years since the Versailles disaster, when the building's third-floor dance floor collapsed during a wedding, killing 23 guests and injuring hundreds. Since then significant progress has been made in addressing structures built using Pal-Kal, the banned ceiling construction method that was a factor in the collapse.

But while most of these buildings have been examined and undergone follow-up monitoring, there is still no complete list of Pal-Kal buildings in Israel, and even today hundreds have not yet been checked to determine if they pose a risk. One inadvertent renovation could lead to a repeat of the Versailles catastrophe. But faulty identification and inaccessible documentation means that many apartment buyers aren't aware of the danger.

"My wife and I were looking to buy a home in central Tel Aviv and found one on Rashi Street that looked too good to be true," relates S., who went house hunting two years ago. "It was a four-room, 100-square-meter apartment with two parking spaces in a relatively new building, and was going for NIS 2.8 million." The real estate agent explained the low price by saying that the owner wanted cash up front.

Everything seemed fine until two days before the contract signing: The owner sent S. a stack of documents that she supposedly hadn't noticed before. S. was shocked to find a declaration by the Tel Aviv municipality that the building was unsafe - it had been built using the Pal-Kal method.

"When I looked into things, I found that after the Versailles disaster the government declared all Pal-Kal buildings to be at risk," says S. "The cities then sent out notices to owners, telling them they needed to determine that their properties were safe so that they would not be designated as hazardous buildings.

"An engineer examined the Rashi Street building and declared it safe, so it should have been removed from the black list," continues S. "But several years later, it turns out, the Interior Ministry stated that Pal-Kal buildings cannot be taken off the danger list and that owners need to have them checked every year."

Combination of factors

On May 24, 2001, the floor at the Versailles banquet hall in Jerusalem's Talpiot neighborhood caved in under the feet of hundreds of wedding guests, killing 23 people. A combination of factors caused the disaster: One was that the floor had been built using the Pal-Kal method, and another was that a wall had been removed during renovations on the floor below. The wall hadn't been designed as a load-bearing wall, but it nevertheless had helped support the ceiling above.

The Pal-Kal construction method was invented by engineer Eli Ron as a quick, easy and cheap way to put up ceilings. Yet it was controversial even before the Versailles tragedy, and it was found not to meet Israeli standards. Yet it was used anyway.

After the disaster, Ron was sentenced to four years in prison, the building's engineers were sentenced to 22 months, and the owners of the Versailles hall were convicted of causing death by negligence and sentenced to 30 months. In addition, the government appointed a commission of inquiry headed by Judge Vardi Zeiler to examine the country's building safety. In 2002 the commission issued its interim conclusions regarding the Pal-Kal method, and in 2003 it submitted its report on Israeli construction practices as a whole.

The interim report recommended banning the Pal-Kal method. But because the country still has millions of square meters of Pal-Kal ceilings, which can't all be demolished, the committee recommended these structures be checked for stability.

In 2002 the government adopted the interim report and decided to set up a staff of professional engineers and administrators, under the auspices of the interior minister, to identify Pal-Kal buildings. In 2007 the ministry transferred responsibility to local authorities and gave them guidelines on how to handle the issue.

The ministry drafted a flowchart for identifying Pal-Kal buildings, informing the owners of the risk, and getting engineers' opinions on the structures' durability. Three categories were established: Buildings requiring only regular monitoring, buildings needing reinforcement, and buildings to be evacuated and demolished.

Dr. Yoav Sarne, chairman of A. Epstein & Sons and president of the Israeli Association of Engineers and Architects, testified before the Zeiler Commission. He explains that most of the residential buildings fall in the first category - those merely requiring periodic inspection.

"The danger isn't great in residential buildings, but it could be quite substantial in public buildings," says Sarne. "The risk is calculated in part based on the load on the structure, which is relatively light in residential buildings. Office buildings have many more people, and filed papers create significant strain. Offices full of binders and papers are very dangerous, so the guidelines call for reducing these loads in Pal-Kal buildings."

Sarne, who for years warned about the dangers of Pal-Kal both before and after the Versailles tragedy, now actually sounds more relaxed: "A building won't collapse due to Pal-Kal construction alone, but due to a combination of circumstances, such as in the Versailles disaster," he says. "Pal-Kal doesn't fall by itself, only with help. The proof is that hundreds of Pal-Kal buildings have been identified yet they aren't constantly collapsing. They may not be up to standard and do pose a certain risk, but they aren't collapsing."

Contradictory numbers

While Sarne says 1,200 buildings in Israel were built using the Pal-Kal system, there is a great deal of confusion among the various authorities on the actual number. The problem is that they need to be identified one by one: Some are merely suspected of being built by the method, while others have been checked and eliminated from the list unbeknown to the Interior Ministry. Government data states there are 605 Pal-Kal buildings and 312 more that need to be investigated. Lists obtained from the method's creator, Eli Ron, are being used to locate the structures.

In Jerusalem, for instance, the ministry claims there are 224 such buildings, while the municipality says there are only 121. When asked about this discrepancy the Interior Ministry responded that it hadn't yet received from the municipality the figures for buildings not built using Pal-Kal. "When the checks are complete it will probably turn out that some of the buildings aren't Pal-Kal structures," said the ministry.

Figures provided by the Jerusalem municipality seem encouraging: Of the 121 buildings, 69 were found not to need reinforcement, 45 already have been reinforced and only eight still require further action.

According to Interior Ministry figures, there are 104 Pal-Kal buildings in Tel Aviv, 51 in Haifa, 52 in Rishon Letzion, 48 in Ashdod, 54 in Eilat and 25 in Be'er Sheva. The data classifies 25% of the 605 buildings on the list as residential, 13% as offices, 13% as commercial, 14% as industrial, 13% as religious institutions, 17% as public buildings, 2% as banquet halls and 2% as hotels.

Many of the municipalities have followed Interior Ministry guidelines, and some even list their unsafe buildings online: Holon has a list of 19 buildings, including four residential buildings; Petah Tikva lists 31 buildings, most industrial or commercial; and Netanya lists 32 buildings as well as their current status.

Risky renovations

Despite the notable progress, the situation is far from ideal. While larger and more assertive local authorities are dealing with their problematic properties, others have a long way to go. Ten years after the disaster, many buildings throughout the country - 312 according to the Interior Ministry - still need to be checked at this point.

In addition, despite a clear directive to place a sign at every Pal-Kal building, residents often try to obscure their building's problem and renovators working in the building are unaware of the danger, according to Eran Siv, the chairman of the Israel Association of Renovation Contractors.

The problem in documenting and identifying the buildings is illustrated by a case handled by Attorney Sagi Greenfeld of the law firm Segev, Kidron, Greenfeld & Co. Greenfeld represented the buyer of an apartment in Bnei Brak. He performed all the necessary background checks, including the property title at the land registry and the municipality's file on the building, without finding anything wrong, he says. Only once the buyer had already moved in and wanted to make renovations was he shocked to discover from the renovator that the ceiling had been built using the Pal-Kal method. The buyer was forced to replace it at a cost of NIS 25,000.

It is very important for people to be aware how sensitive Pal-Kal ceilings are to structural changes. In the Versailles tragedy, Pal-Kal wasn't the sole cause of the disaster: Renovations below the hall included the removal of a wall that wasn't designated a structural support, so there was nothing improper in moving it. But because the ceiling was a flimsy Pal-Kal structure, the wall had in fact served as its support.

"In a Pal-Kal structure a wall cannot be changed without an engineer's approval," says Sarne. "A concrete block wall, as opposed to a supporting wall, isn't intended to bear loads, but does so nonetheless. In a Pal-Kal building this wall could be holding up the ceiling. Therefore, except for drywall, moving a wall or making an opening in one requires an engineer's opinion."

Renovation contractors aren't authorized to perform these tests. Siv of the Association of Renovation Contractors and Zvi Sharf, its operations manager, warn that another tragedy could occur because the renovations industry is unorganized. They say that of the 14,600 renovation contractors, only 300 to 400 have qualifications; most of the rest have no professional training or certifications. A lack of training could lead to mistakes and cause the next disaster, they warn.