Minute by minute: what we know about the collapse of a building in Miami; victims, rescue efforts and the impact of the tragedy

A freshly obtained photo from 2018 shows the early stages of a crack in the concrete in the pool equipment room at the Surfside building that collapsed last week. The image contrasts with another from the same room that was supposedly taken a few days before the collapse and that has been a key piece for experts working to determine the cause of the tragedy.

The 2018 photo shared with CNN by Tom Henz, a mechanical engineer whose firm did an electrical and mechanical inspection of the Champlain Towers South building that year as part of its 40-year recertification process, shows a crack around the edge of a beam that walk across the top of the room.

Engineers and experts consulted by CNN said the same crack appears to be seen in the 2021 photograph, which was published earlier this week by the Miami Herald, although the state looks worse in the most recent photo.

The cause of the deterioration is unclear.

After inspecting the building in 2018, engineer Frank Morabito wrote in a report that the “failed waterproofing” under the pool deck was “causing significant structural damage to the concrete structural slab below these areas” and cautioned that not replacing it in the near future would cause “concrete deterioration to expand exponentially.”

A 2021 letter addressed to the residents of the building from the condo association president confirmed that the exponential deterioration had indeed occurred in the years in between.

“The deterioration of concrete is accelerating,” wrote Jean Wodnicki, president of the association. “The observable damage, such as in the garage, has significantly worsened since the initial (2018) inspection.”

Experts CNN spoke with said the progression seen in the fissure between the two images could be an indication of deterioration caused by the waterproofing problem described by Morabito. Or, according to some, the concrete surrounding the crack could have been dislodged during the three-year interval and revealed the deepest crack seen in the 2021 photograph.

It could be below the surface. Sometimes there is a fragment and it is enough with a little wind or someone hitting (the surface) to make it detach. It’s hanging by a hair, basically, ”said Greg Batista, Florida structural engineer and managing director of construction.

In the days since the building collapsed, which has left at least 18 people dead and 145 unaccounted for, it emerged that the base of the tower may be a possible point of failure. In addition to Morabito’s report, two witnesses have also claimed that they saw the beginning of the collapse by the pool deck.

On Tuesday, a resident of the tower who escaped just before its collapse told CNN that she saw the garage, which is partly under the pool, fall first, before the rest of the building. The account was in line with that of another woman, Cassondra Stratton, who told her husband in a phone call from a tower condo that she saw a hole where the pool used to be, her husband told the Miami Herald.

Spalling, or cracking, can occur when steel reinforcements in concrete begin to rust and expand due to exposure to air and water. The spread is often compared to cancer.

“Once this kind of deterioration starts, it’s insidious, it just keeps going. Unless something is done about it, everything is going to collapse, all the concrete is going to collapse, “said Matthys Levy, engineer and author of the book” Why Buildings Fall Down, “among others.
Engineers consulted by CNN disagreed that a failure in the pool equipment room area or around the pool deck could have caused the building to collapse, but many pointed out that the damage seen in the room was probably an indication of maintenance problems in the building.

“In general terms, it shows how bad the concrete was. You can draw whatever conclusions you want, (for example) that maybe the rest of the concrete was just as bad, ”Levy said.