SURFSIDE, Fla. (NewsNation Now) — As search and rescue efforts continue, investigators are seeking answers as to what caused a 12-story condo building in Florida to collapse early Thursday morning.

The next phase of the investigation will be to determine what brought down the Champlain Towers South Condo — it’s a process that could take years.

The seaside condo development was built in 1981.

“Being in such close proximity to the ocean and on a coastline, there’s a high salinity in the air which slowly causes chlorides to form on the rebar of the concrete building,” said Nester Cueto, S.I. of Cueto Engineering, LLC. “When that happens, it causes an electrochemical reaction which causes rust. That rust then expands and contracts with temperature and the corrosion process. That can cause phenomena called concrete spalling and causes chunks of concrete to fall out.”

For that reason, Miami Dade County requires 40-year building recertification to ensure they’re safe for continued use. The Chaplain Towers mandated recertification process was ongoing; however, it’s unclear how much engineering work had been done or what the recommendations were to keep the building structurally sound.

Cueto, who designs and engineers buildings in Miami, compares Thursday’s collapse to the World Trade Center collapse on 9/11.

“Planes flew into the World Trade Center and the heat of the jet engine fuel melted the structural steel,” Cueto said. “With progressive collapse, it usually starts with a local failure and a load-bearing element of the building. Eventually, it results in either partial collapse or total collapse of the building. ”

He says people should think of it like a Jenga stack.

“If you pull out one of those crucial members, the whole thing’s coming down,” Cueto said. “The load keeps dropping depending on where the failure occurred, and those members were not intended for that amount of load which causes a progressive collapse of the structure.”

Daniel Ciraldo, executive director of the Miami Design Preservation League, says the building’s problem was not its age.

“There are many buildings in Miami-Dade County that are more than 40 years old — which, thankfully have undergone this [recertification] process,” Ciraldo said on NewsNation Prime. “After the first 40-year recertification, there’s a requirement for every 10 years to get another recertification. What we see here with this building, the big mystery is it as just coming up on its 40th birthday, and so they were in the process of doing those checks to the structural systems, to the electrical systems. It will be interesting to see if the engineers that were currently working on that study…if information was identified in order to try to hone in on what caused this horrible tragedy.”

Addressing reports that the building was already sinking at an alarming rate, Ciraldo says that study will be a reference point for investigators.

“I understand from that study though that the land area that was subsiding appeared to be isolated to that building. Thankfully, that’s not a common occurrence that I’ve heard of,” he said.

Ciraldo noted it was important not to jump to conclusions into the cause of the partial collapse.