NIST releases preliminary findings into 2021 Champlain Towers Collapse

CBS News

24-06-2025

The National Institute of Standards and Technology's National Construction Safety Team (NIST) has released a 90-minute video update on its investigation into the June 2021 partial collapse of the Champlain Towers South building in Surfside.
Investigation leads Judith Mitrani-Reiser and Glenn Bell outline progress, preliminary findings and collapse hypotheses in the video.
Higher-likelihood hypotheses
Mitrani-Reiser said the team has identified several design and construction issues that weakened the building, including understrength structural design and misplaced steel reinforcement in the pool deck, which had low safety margins.
Bell noted heavy planters, added sand, pavers and corrosion of steel reinforcement further diminished the pool deck's strength, making its failure a higher-likelihood scenario.
The team also considered tower-related issues, such as water-damaged basement columns or a slab-beam-column joint failure, as plausible causes, Bell said.
Lower-likelihood scenarios
The team found no evidence of karst voids or pile failure beneath the building, Mitrani-Reiser said, citing satellite data showing no ground settling and tests confirming adequate pile strength.
Bell also described the separation of the pool deck from the south basement wall as a lower-likelihood scenario.
The investigation relies on physical evidence, imagery, witness interviews and audio-video analysis, Mitrani-Reiser said, noting a novel soundwave comparison technique helped refine the collapse timeline.
The team expects to complete its report in 2026, Bell said.