Champlain Tower: Experts weigh in on what went wrong

Experts say no single issue could have caused the Champlain Tower South condominium complex to collapse, but a confluence of factors likely did.

Experts said it's unlikely a single issue caused the deadly collapse of the Champlain Tower South condominium complex, but a confluence of factors may have. The oceanfront Surfside, Florida, complex, which was built in the 1980s and up for its 40-year recertification, collapsed Thursday. At least four people are dead, and 159 are still missing, officials said Saturday. Jason Borden, a structural engineer who conducted a site survey at the building last year, said the findings of a structural field service report from 2018, publicly released overnight Friday, described "abundant cracking and spalling" and "failed waterproofing" that could have contributed to the collapse. "Any of those items by themselves are unlikely to have been the sole reason why the collapse happened, but those combined with other things also could have been an issue that added up to the overall net result," Borden told ABC News.