A year after Surfside condo collapse, investigators still don't know the exact cause

Nearly one year after the condominium collapse in Surfside, Florida, that killed 98 people, federal investigators said Thursday that there are "many factors" that likely contributed to the failure.

During an online presentation to the National Construction Safety Team Advisory Committee, one of the lead federal investigators, Glenn Bell, said the National Institute of Standards and Technology has not "ruled out any scenarios" and currently has "about two dozen hypotheses" that are being "actively considered" in its ongoing investigation.

None of the hypotheses is considered a "leading theory" at this point, he said.

Champlain Towers South, a 13-story oceanfront residential building in Miami-Dade County, partially collapsed overnight on June 24, 2021. The rest of the building was demolished 10 days later due to concerns over structural integrity.

"I've been investigating and studying structural failures for over 40 years and I can say that this investigation is one of the most difficult and complex of its type ever undertaken," Bell told the committee.

Bell said that even after nearly a year of analysis, there remains no "clear initiating event" that triggered the failure. He pointed to several possibilities that NIST is investigating, including the corrosion of the reinforcing steel in the plaza slab of the building, and the possible impact of the construction of a neighboring condo building.

Other possibilities Bell mentioned are the possible impact of climate change that may have affected the foundation of the oceanfront structure, and the construction of a penthouse that exceeded local height restrictions.

Bell said NIST is also reviewing public and private recordings related to the building, and conducting interviews with people who have knowledge of the design and construction practices that were prevalent in South Florida at the time of building's construction.

"Why did the structure stand and then partially collapse after 40 years? What changed in the loading and/or the strength of the structure? There are no clear answers to these questions either," Bell said.

At the end of the investigation, NIST plans to publish a written report and create several "realistic animations" to convey their findings.

The agency does not yet have a timeline for when the investigation will be concluded.

"The entire team is driven and committed to getting to the bottom of what happened at Champlain Towers South," said Dr. Judith Mitrani-Reiser, NIST's associate chief of materials and structural systems. "After we determine the causes of collapse, we will prepare recommendations for codes, standards, and practices, and any continued research indicated by our findings, so that a disaster like this never happens again."

Last month, lawyers announced a proposed settlement reached for families of those who died in Champlain Towers South would exceed $1 billion.