Students were "packed like sardines" on balcony before collapse
Irish students were "packed like sardines" on a balcony which collapsed in California, killing six of them and injuring seven others at a 21st-birthday party, an expert has said.
Engineering crews have been inspecting jagged broken beams of wood sticking from the building in Berkeley, marking where the balcony had snapped off. Pieces of wood came away, falling to the ground, as the engineers touched them.
Structural engineer Grace Kang said it may have been overloaded if, as city authorities have said, it was holding 13 people.
Berkeley officials said the building code at the time of construction required the balcony hold at least 60lbs per square foot. The city's requirement for balconies has since been raised to 100lbs.
The exact dimensions of the balcony that failed were not released. Estimates varied, with mayor Tom Bates saying city officials thought it was about 9.5 x 5ft, but Ms Kang, who is also a spokeswoman for Pacific Earthquake Engineering Research Centre at Berkeley, said it looked to her to be 4 x 6ft, or 24 sq ft.
The larger estimate would mean the balcony should hold 2,850lbs, while Ms Kang's estimate would be half that. Ms Kang said it appeared small for 13 people.
"They were packed like sardines, and then they were moving," she said. When people are moving it "may further exacerbate" the strain.
The apartment building had wood-frame construction, and the balcony was cantilevered out from the building, with no additional support beneath. Both can make a balcony more vulnerable to dry rot and the effects of weather in general, Ms Kang said.
The party, thrown by the visiting students, turned to horror in the early hours when the fifth-floor balcony they were on gave way with a sharp crack, hurling them about 50 feet on to the pavement.
Police, firefighters and building officials are investigating why the small balcony broke loose from the stucco apartment house near the campus of the University of California, Berkeley.
High school pupil Jason Biswas' family was awakened by the noise. "They thought there was an earthquake. But then we looked out the window and saw seven or eight people on the ground," the 16 year old said. "There were piles of blood everywhere."
Five of the dead were 21-year-olds from Ireland who were in the country on J1 visas that enable young people to work and travel in the US over the summer, while the sixth victim, an Irish-American, was from California.
The accident brought an outpouring of grief in Ireland from the prime minister down, with the country's consul general in San Francisco calling it a "national tragedy".
Police had received a complaint about a loud party in the apartment about an hour before the accident but had not yet arrived when the metal-rail balcony gave way just after 12.30am. It landed on the fourth-floor balcony just beneath it, leaving the pavement strewn with rubble and the red plastic cups that are practically standard at college parties.
"I just heard a bang and a lot of shouting," said Dan Sullivan, a 21-year-old student from Ireland who was asleep in the five-storey building. Mark Neville, another Irish student in the building, said: "I walked out and I saw rubble on the street and a bunch of Irish students crying."
The dead were identified as Ashley Donohoe, 22, of Rohnert Park, California; and Olivia Burke, Eoghan Culligan, Niccolai Schuster, Lorcan Miller and Eimear Walsh, all 21, from Ireland. The Irish students attended various colleges in Dublin.
The J1 programme brings 100,000 college students to the US every year, many landing jobs at resorts, summer camps and other attractions. The San Francisco Bay area is especially popular with Irish students, about 700 of whom are working and playing there this summer, according to Ireland's consul general Philip Grant. Many work at Fisherman's Wharf and other tourist sites.
Sinead Loftus, 21, who attends Trinity College Dublin and is living this summer in a different apartment in Berkeley, said Berkeley is "the Irish hub".
"It's student-friendly, it's warm and it's a lot cheaper than San Francisco," she said.
Investigators will look at things such as whether the balcony was built to code, whether it was overloaded and whether rain or other weather weakened it, said Kevin Moore, chairman of the structural standards committee of the Structural Engineers Association of California.
Balconies are exposed to the elements, "so deterioration can play a part", he said. Weather, "overloading, inadequate design, all these things come up in the investigations".
City inspectors have banned the use of the building's other balconies while they are checked for safety.
The Library Gardens apartment complex, completed in 2007, is in a lively part of central Berkeley close to the campus and is a popular place for students to live.
Berkeley police chief Michael Meehan said the response to the noise complaint had been given a lower priority after police received a shooting call elsewhere.
The building is owned by BlackRock, the largest asset-management fund in the US, according to city officials, and managed by Greystar Management, whose website says it operates more than 400,000 units in the US and abroad.
In a statement, Greystar extended condolences to the victims' families and added: "The safety of our residents is our highest priority and we will be working with an independent structural engineer and local authorities to determine the cause of the accident."
On the closed street below, a shrine was growing: flowers, a pack of cigarettes, a Cal Berkeley banner, condolence notes. Victims' relatives have begun arriving from Ireland.
Ms Walsh and Ms Burke were hostesses at Haza Zen, a Japanese restaurant at Pier 39, said restaurant owner Alvin Louie.
"They were great young kids, very enthusiastic, full of energy," he said. "We're all devastated."
Berkeley spokesman Matthai Chakko said officials had not measured the balcony to find out how big it was and how much weight it was built to bear.
He said there was no city requirement to post a weight restriction for balconies in apartments.