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This outreach will help ensure that the team’s findings and recommendations lead to improvements to codes, standards and practices that can prevent similar
The National Construction Safety Team has reached an important milestone in its investigation into the 2021 partial collapse of Champlain Towers South.
This update provides a summary of the NCST Champlain Towers South investigation’s history and progress, shares preliminary findings, and highlights potential impacts this complex investigation could have on building codes and standards. Investigative lead Judith Mitrani-Reiser and co-lead Glenn Bell explain how the team determined that some of the failure hypotheses are more likely than others. Mitrani-Reiser and Bell describe the extensive planning and coordination that helped the team systematically conduct thorough analyses, testing and modeling to reach their investigation's preliminary findings.
Press Conference Videos (Captions in English and Spanish)
NIST Announces Expert Team to Investigate the Champlain Towers South Collapse
The U.S. Department of Commerce’s National Institute of Standards and Technology (NIST) announced the expert team members who will conduct a technical investigation into the June 24, 2021, partial collapse of the Champlain Towers South condominium in Surfside, Florida.
NIST Announces Full Investigation on Champlain Towers South Collapse
The U.S. Department of Commerce’s National Institute of Standards and Technology (NIST) announced it would launch a full technical investigation into what caused the partial collapse of the Champlain Towers South Condominium in Surfside, Florida, on June 24, 2021.
Materials Testing time-lapse videos
NCST Slab-beam-column test timelapse
This time-lapse video of a test at the University of Minnesota shows how a full-scale replica of a reinforced concrete slab, beam and column from the Champlain Towers South building would perform under certain conditions believed to be present at the time of the collapse. In this test, the slab and beam on the left break away from the column, simulating the collapse of the pool deck.
NCST Slab-beam-column test set-up timelapse
Full-scale replicas of portions of the Champlain Towers South building were built at the University of Washington and University of Minnesota and tested to failure. Researchers at the University of Minnesota carefully prepare a replica of a Champlain Towers South reinforced concrete slab, beam and column connection for testing.
B-Roll Videos
B-Roll Video Reel #1 - Champlain Tower South NIST Investigation
To download this video, click the top right file button.
B-Roll Video Reel #2 - Champlain Tower South NIST Investigation
To download this video, click the top right file button. Captions forthcoming.
B-Roll Reel #3- Champlain Tower South NIST Investigation
To download this video, click the top right file button.
B-Roll Reel #4: Champlain Tower South NIST Investigation
To download this video, click the top right file button.
Rebar Testing. To download this video, click the top right file button.
B-Roll Reel #8: Champlain Tower South NIST Investigation | Pool-Deck and Tower Interface Laboratory Testing
Pool Deck and Tower. To download this video, click the top right file button.
NCST Insider Videos
NCST Insider | feat. Emel Ganapati
Introducing Miami-based N. Emel Ganapati, who will serve as the Social Science Team Leader on the Evidence Preservation Project. She will lead interviews of residents, first responders, family members and others with knowledge of the building’s condition and collapse.
NCST Insider | feat. Kamel Saidi
Introducing Kamel Saidi, who is serving as a co-lead on the Remote sensing and Data Visualization Project.
NCST Insider | feat. Malcolm Ammons
NIST’s Champlain Tower South collapse investigation is introducing Malcolm Ammons, who is supporting the Evidence Preservation Team, Building & Code History Team, Materials Science Team and Structural Engineering Team.
NCST Insider | feat. Christopher Segura
Introducing Christopher Segura, who is serving as a co-leader for the evidence preservation project in the investigation.
NCST Insider | feat. Marisa McCormick
Introducing Marisa McCormick, who supports the evidence preservation and material science projects.
NCST Insider | feat. David Goodwin
Introducing David G. Goodwin Jr., who is co-leader of the evidence preservation project in the investigation.
NCST Insider | feat. Georgette Hlepas
Introducing Georgette Hlepas, who serves as co-leader of the remote sensing and data visualization project in the investigation.
NCST Insider | feat. Vincent Lee
Introducing Vincent Lee, who supports the remote sensing and data visualization project in the investigation.
NCST Insider | feat. Fahim Sadek
Introducing Fahim Sadek, co-leader for the structural engineering project in the investigation.
NCST Insider | feat. Jim Harris
Introducing Jim Harris, a co-lead on the Building and Code History team.
NCST Insider | feat. Jack Moehle
Introducing Jack Moehle, who is a co-lead on the Structures Project.
Photo Gallery
In this January 2022 photo, physical evidence from both the collapsed and imploded sections of Champlain Towers South is stored in a secure warehouse where it has been carefully cataloged and evaluated by members of the National Construction Safety Team investigating the June 24, 2021, collapse.
Credit:
NIST
In this January 2022 photo, National Construction Safety Team Evidence Preservation project co-lead David Goodwin evaluates nondestructive test methods for examining structural samples from Champlain Towers South.
Credit:
NIST
In this January 2022 photo, National Construction Safety Team members (L-R) Malcolm Ammons, Marisa McCormick and David Goodwin examine structural evidence from Champlain Towers South for details that can be included in a physical evidence database.
Credit:
NIST
In this January 2022 photo, National Construction Safety Team support member Ruthie Corzo evaluates nondestructive protocols to measure chloride content in concrete with a handheld analyzer.
Credit:
NIST
In this January 2022 photo, National Construction Safety Team member Malcolm Ammons systematically records information about physical evidence from Champlain Towers South that will help provide clues to its original location and condition.
Credit:
NIST
In this January 2022 photo, National Construction Safety Team member Marisa McCormick measured steel rebar in a concrete column from Champlain Towers South.
Credit:
NIST
In this January 2022 photo, National Construction Safety Team member Daniel Sawyer evaluates a 3D scanning protocol for physical evidence from Champlain Towers South.
Credit:
NIST
In this January 2022 photo, National Construction Safety Team members Malcolm Ammons and Stephanie Moffitt conduct nondestructive measurements on a single-story column from the garage of Champlain Towers South.
Credit:
NIST
In this February 2022 photo, National Construction Safety Team Remote Sensing and Data Visualization project co-lead Kamel Saidi processes a 3D scan of physical evidence from Champlain Towers South.
Credit:
NIST
NIST staff members at the holding site for evidence that may help in the investigation into what caused the partial collapse of the Champlain Towers South condominium.
Credit:
NIST
In this July 6, 2021, photo, NIST engineering experts examine a concrete column from the Champlain Towers South condominium before it was taken from the collapse site for preservation.
Credit:
NIST
In this July 7, 2021, photo, a concrete column is moved from the debris pile of the Champlain Towers South condominium to a staging area for tagging before being tagged and catalogued as evidence.
Credit:
NIST
In this July 1, 2021, photo NIST staff members examine pieces of concrete removed from the debris pile at the site of the Champlain Towers South building partial collapse.
Credit:
NIST
In this July 2, 2021, photo, a NIST staff member tags and photographs a building element that has been identified for preservation as evidence in the staging area near the site of the Champlain Towers South building collapse.
Credit:
NIST
In this July 6, 2021, photo, NIST engineering experts photograph and tag concrete columns from the collapsed Champlain Towers South condominium. Building elements were marked and tagged with unique identifying information before being moved to a long-term holding facility.
Credit:
NIST
In this July 6, 2021, photo, NIST engineering experts tag and photograph concrete columns from the collapsed Champlain Towers South condominium. Building elements were marked and tagged with unique identifying information before being moved to a long-term holding facility.
Credit:
NIST
In this July 6, 2021, photo, NIST engineering experts tag concrete columns from the collapsed Champlain Towers South condominium. Building elements were marked and tagged with unique identifying information before being moved to a long-term holding facility.
Credit:
NIST
The site of the Champlain Towers South partial collapse in Surfside, Florida.
Credit:
NIST
View of the Champlain Towers South condominium site from a balcony in an adjacent building to the south. NIST has positioned imaging equipment on the balcony to record the locations of items being preserved for study, and to record changes to the site as debris is removed.
Credit:
NIST
Cameras and lidar used by NIST and its partners scan and record the site of the Champlain Towers South condominium.
Credit:
NIST
Building elements such as columns, beams and floor slabs are identified, removed from the debris pile, tagged and moved to a holding area before the evidence is transported by police escort to an offsite storage facility where it will be preserved for study.
Credit:
NIST
NIST is using nondestructive test methods to determine the properties of concrete from the site of the partial collapse of the Champlain Towers South condominium. Here, an engineer evaluates the strength and quality of a concrete column using a method called Ultrasonic Pulse Velocity (UPV), which measures the velocity of an ultrasonic pulse passing through the sample.
Credit:
NIST
Building elements such as columns, beams and floor slabs are identified, removed from the debris pile, tagged and moved to a holding area before the evidence is transported by police escort to an offsite storage facility where it will be preserved for study.
Credit:
NIST
Building elements such as columns, beams and floor slabs are identified, removed from the debris pile, tagged and moved to a holding area before the evidence is transported by police escort to an offsite storage facility where it will be preserved for study.
Credit:
NIST
NIST and National Science Foundation staff members discuss imaging of the Champlain Towers South site using lidar, which uses pulsed laser light to measure distances to objects, creating a 3D representation of the site.
Credit:
NIST
NIST is using nondestructive test methods to determine the properties of concrete from the site of the partial collapse of the Champlain Towers South condominium. Here, an engineer evaluates the strength and quality of a concrete column using a method called Ultrasonic Pulse Velocity (UPV), which measures the velocity of an ultrasonic pulse passing through the sample.
Credit:
NIST
NIST and U.S. Army Corps of Engineers staff members inspect a building element from the Champlain Towers South partial collapse in Surfside, Florida, for its evidentiary potential.
Credit:
NIST
National Construction Safety Team members, investigating the partial collapse of the Champlain Towers South building, oversee the safe move of physical evidence into a new warehouse (May 2023).
Credit:
NIST
Concrete column specimens from the Champlain Towers South building in the new warehouse space, which will allow investigation team members to safely conduct the next phase of material and structural testing (May 2023).
Credit:
NIST
Evidence from the Champlain Towers South building in Surfside, Florida, was transported to a new warehouse this spring, where experts will extract concrete core and steel reinforcing bar samples for material testing (May 2023).
Credit:
NIST
The NCST experts began conducting nondestructive testing of the evidence in its new location to identify which pieces would be suitable for coring of the concrete. Hammer tapping, shown here, can reveal voids and degradation within a section of concrete (May 2023).
Credit:
NIST
Specialty moving methods, such as using steel beams to provide stiffness, were employed for the most fragile pieces of evidence from the Champlain Towers South collapse before they were lifted and moved with a forklift (May 2023).
Credit:
NIST
Each piece of evidence from the Champlain Towers South collapse was documented in several ways to ensure the chain of custody could be maintained as it was transported from the existing warehouse to the new warehouse space (May 2023).
Credit:
NIST
Cores of concrete and reinforcing steel are extracted from a pool deck slab specimen collected from the collapsed Champlain Towers South condominium, as part of the National Construction Safety Team investigation into the technical cause of the collapse (September 2023).
Credit:
NIST
Cores of concrete and reinforcing steel collected as part of the National Construction Safety Team investigation into the 2021 collapse of the Champlain Towers South condominium await testing (July 2023).
Credit:
NIST
A NIST National Construction Safety Team investigator examines a concrete core collected from a Champlain Towers South building evidence specimen prior to mechanical testing (July 2023).
Credit:
NIST
A NIST National Construction Safety Team (NSCST) investigator checks a core prior to compression and modulus of elasticity (MOE) testing, as part of the NCST investigation into the 2021 collapse of the Champlain Towers South condominium (July 2023).
Credit:
NIST
A U.S. Army Corps of Engineers (USACE) staff member prepares a concrete core for a compression test, as a part of the National Construction Safety Team investigation into the 2021 collapse of the Champlain Towers South condominium (July 2023).
Credit:
NIST
A U.S. Army Corps of Engineers staff member and National Construction Safety Team member examine a core extracted from Champlain Towers South evidence specimens following compressive testing of the core (July 2023).
Credit:
NIST
Concrete cores extracted from Champlain Towers South evidence specimens undergo compressive testing until they fail. These tests, conducted by the U.S. Army Corps of Engineers, help the National Construction Safety Team members determine the material properties of the construction elements (July 2023).
Credit:
NIST
Engineers evaluate rebar samples before they are entered into a device that tests how they deform and break (February 2024).
Credit:
R. Eskalis/NIST
Samples of concrete cores from Champlain Towers South are tested for how well they carry electrical current when wet. The greater the capacity to conduct current, the faster rust can form on steel reinforcement within the concrete (February 2024).
Credit:
R. Eskalis/NIST
Concrete samples are soaked in water in a test designed to measure how quickly water and the chemicals it carries are absorbed (August 2024).
Credit:
R. Eskalis/NIST
Georgette Hlepas, Kamel Saidi and Judith Mitrani-Reiser (left to right) review a computer model of Champlain Towers South. Models like this one are used to determine where pieces of evidence came from before the collapse (April 2023).
Credit:
L. Gerskovic/NIST
National Construction Safety Team members Kamel Saidi (left) and Georgette Hlepas review an aerial photo of the collapse site. More than 600 pieces of the structure were recovered from the site. This evidence contains important information about how the building was made, the strengths and weaknesses of different parts of the structure, and how the collapse itself may have unfolded. It’s important to know where the pieces of evidence came from, and computer tools like these help investigators put the pieces of the puzzle together (April 2023).
Credit:
L. Gerskovic/NIST
Using a magnifying glass, a NIST researcher carefully examines a hard drive collected from the site of the Champlain Tower South collapse (Nov. 2024).
Credit:
R. Eskalis/NIST
A NIST researcher carefully removes the magnetic disk from a damaged hard drive recovered from the site of the Champlain Towers South building, which partially collapsed on June 24, 2021. Twenty-five hard drives from the building were recovered and analyzed to determine if any belonged to the digital video recorder that stored footage from the building’s security cameras. Unfortunately, the hard drives were too damaged to read, even with the most advanced forensic techniques available (Nov. 2024).
Credit:
R. Eskalis/NIST
Judith Mitrani-Reiser, Kamel Saidi and Daniel Gopman (left to right) examine microscopic images of a damaged hard drive recovered from the collapse site (Nov. 2024).
Credit:
R. Eskalis/NIST
In the weeks following the June 24, 2021, partial collapse of the Champlain Towers South condominium in Surfside, Florida, NIST National Construction Safety Team members conducted remote sensing of the site using lidar technology, which sends out rapid pulses of light and records the reflections to create a spatial map of individual points reflected from surfaces on the ground. This image was captured on July 14, 2021, and provides important information on the post-collapse geometry of building components. Red points represent data on the south basement wall, and yellow points represent data on the privacy wall above.
Credit:
NIST
The University of Minnesota’s Multi-Axial Subassemblage Testing, or MAST, Laboratory built full-scale replicas of building components from the Champlain Towers South building. In this photo, forces are exerted on a replica that combines concrete slabs, columns and a beam.
Credit:
NIST
A replica of a reinforced concrete column from the Champlain Towers South building is tested to failure at the University of Washington’s Large-Scale Structural Engineering Testing Laboratory, or SETL. The test apparatus pushes down on the column, applying compression forces along its axis, to provide information on its strength.
Credit:
NIST
A replica of a Champlain Towers South reinforced concrete column whose construction did not meet original building design requirements was tested at the University of Washington. Specifically, the as-built columns had “short lap splices,” that is, the reinforcement did not overlap sufficiently to provide the required strength (Aug. 2024).
Credit:
NIST
A researcher examines replicas of Champlain Towers South building components following a test at the University of Minnesota that strained them to breaking (Jan. 2025).
Credit:
NIST
Full-scale replicas of portions of the Champlain Towers South building were built at the University of Washington and University of Minnesota and tested to failure. After being tested to failure at the University of Minnesota, this reinforced concrete specimen illustrates how a slab, beam and column connection in the pool deck may have failed (Jan. 2025).
Credit:
NIST
National Construction Safety Team Champlain Towers South investigative lead Judith Mitrani-Reiser confers with Jim Harris, co-lead of the investigation’s Building and Code History Project, and investigative co-lead Glenn Bell (Jan. 2025).
Credit:
NIST
National Construction Safety Team member Jim Harris, co-lead of the Champlain Towers South investigation’s Building and Code History Project, observes a test of a replica concrete slab-beam-column connection at University of Minnesota (Jan. 2025).
Credit:
NIST
Full-scale replicas of portions of the Champlain Towers South building were built at the University of Washington and University of Minnesota and tested to failure. This image shows the results of a test conducted at the University of Minnesota’s Multi-Axial Subassemblage Testing (MAST) Laboratory in which a concrete slab and beam at left break apart from the column, simulating the collapse of the pool deck (Jan. 2025).
Credit:
NIST
Full-scale replicas of portions of the Champlain Towers South building were built at the University of Washington and University of Minnesota and tested to failure. This image shows the results of a test conducted at the University of Minnesota’s Multi-Axial Subassemblage Testing (MAST) Laboratory in which the beam to the right is pushed down and to the right, simulating the collapse of the pool deck (Jan. 2025).
Credit:
NIST
Full-scale replicas of portions of the Champlain Towers South building were built at the University of Washington and University of Minnesota and tested to failure. This image shows a specimen at the University of Minnesota before the test (Jan. 2025).
Credit:
NIST
Full-scale replicas of portions of the Champlain Towers South building were built at the University of Washington and University of Minnesota and tested to failure. This image shows a replica of a reinforced concrete slab, beam and column before testing at the University of Minnesota’s Multi-Axial Subassemblage Testing (MAST) Laboratory (Jan. 2025).
Credit:
NIST
A replica of a Champlain Towers South reinforced concrete slab, beam and column after testing at the University of Minnesota’s Multi-Axial Subassemblage Testing (MAST) Laboratory shows a failed slab joint (Jan. 2025).
Credit:
NIST
A replica of a Champlain Towers South steel reinforced concrete slab-column connection tested at the University of Washington shows a type of failure called “shear failure,” which results from the slab pushing down over the column (Feb. 2025).
Credit:
NIST
Full-scale replicas of portions of the Champlain Towers South building were built at the University of Washington and University of Minnesota. A replica of a reinforced concrete column whose construction did not meet original building design requirements was tested to failure. Specifically, the as-built columns had “short lap splices,” that is, the reinforcement did not overlap sufficiently to provide the required strength (Aug. 2024).
Credit:
NIST
Experts examine cracks in a reinforced concrete slab after a test of a slab-column connection at the University of Washington (UW) (June 2025).
Credit:
NIST
NIST NCST investigators monitor the progress of a slab-beam-column test at the University of Minnesota (June 2025).
Credit:
NIST
Replicas of Champlain Towers South building components were tested until failure at the University of Minnesota. This image shows a failed connection between the pool deck slab-beam and the slab-drop-beam.
Credit:
NIST
Researchers used a saw to cut into a steel-reinforced concrete slab following a slab-column connection test at the University of Washington. The cut reveals shear cracking and failure at the surface (June 2025).
Credit:
NIST
An expert examines cracks in a steel-reinforced concrete slab after a slab-column connection test at the University of Washington (June 2025).
Credit:
NIST
An expert examines cracks in a steel-reinforced concrete slab after a slab-column connection test at the University of Washington (June 2025).
Credit:
NIST
An expert examines a test specimen that includes intentionally corroded steel reinforcement at the University of Washington (June 2025).
Credit:
NIST
An expert examines cracks at the top of a steel-reinforced concrete slab following a slab-column connection test at the University of Washington (June 2025).
Credit:
NIST
Building component replicas undergoing a slab-beam-column test at the University of Minnesota's MAST Facility (June 2025).
Credit:
NIST
A NIST NCST investigator examines the underside of a test specimen following a slab-beam-column test at the University of Minnesota (June 2025).
