Federal investigators examining the deadly collapse of the Champlain Towers South condominium building in Surfside, Florida, have revealed that the construction of the property’s pool deck "deviated from design requirements." 

The changes added to the "low margins against failure" that the housing complex was facing before it partially collapsed in June 2021, killing 98 people, according to the National Institute of Standards and Technology (NIST). 

"The team’s preliminary evaluation of physical and historical evidence... revealed how the construction of the pool deck deviated from design requirements," the NIST said in a statement Thursday.

"Specifically, the team found that the number of slab reinforcing bars centered over vertical columns was inadequate and that the reinforcing bars in the top of the slab in the vicinity of the columns were spaced farther apart than the design required," it added. "These deviations weakened the slab-column connections." 

POOL DECK AT SURFSIDE CONDO THAT COLLAPSED HAD ‘SEVERE STRENGTH DEFICIENCY,’ INVESTIGATORS SAY 

Months ago, a report emerged that investigators found that the pool deck at Champlain Towers South had a "severe strength deficiency." 

The steel reinforcement inside the concrete slabs of the pool deck was found to have been buried deeper in concrete than what initial designs planned for, while planters placed on top of it were heavier than originally designed, adding more weight to the structure, The New York Times reported.

Layers of sand and paving stones later were added to the top of the pool deck, and there also were signs of corrosion in some parts of the steel reinforcement, leaving the structure overall with a "critically low" margin to safeguard against failure, the investigators reportedly determined at the time.

SURFSIDE CONDO BUILDING COLLAPSE VICTIMS REACH $997 MILLION SETTLEMENT 

The building partially collapsed on June 24, 2021. About 10 days later, what remained was demolished. 

"Understanding exactly what caused this collapse is taking meticulous investigation and the collection of copious amounts of evidence and information," Joannie Chin, the director of NIST’s engineering laboratory, said in a statement Thursday. "Our team members are dedicated to unraveling the complexities of this tragic event, and their rigorous research and analysis will not only help us understand the likely technical cause of the collapse but will improve the safety of our communities." 

The NIST is aiming to release its final report including findings and recommendations by June 2025.