AN ENGINEERING FIRM estimated nearly three years ago that major repairs costing more than nine million US dollars (€7.5 million) were needed to secure the oceanfront building near Miami that collapsed on Thursday, according to newly released emails.

An email from Morabito Consultants was among a series of documents released by the city of Surfside as rescue efforts continued at the site of the collapsed apartment block, where more than 150 people remained unaccounted for. At least five people were killed in the collapse.

The release of the 2018 cost estimate followed the earlier publication of another document from the firm showing the building’s ground-floor pool deck was resting on a concrete slab that had “major structural damage” and needed to be extensively repaired.

That report also uncovered “abundant cracking and spalling” of concrete columns, beams and walls in the parking garage.

The report did not warn of imminent danger from the damage, and it is unclear if any of the damage observed was responsible for the collapse of Champlain Towers South.

The cost estimate showed that repairs across the entire building would cost more than 9.1 million US dollars (£6.6 million), with the cost of work at the garage, entrance and pool deck alone accounting for more than 3.8 million US dollars (£2.7 million). The work had not been done by the time the building collapsed on Thursday morning.

The earlier report said the waterproofing under the pool deck had failed and had been improperly laid flat instead of sloped, preventing water from draining off.

“The failed waterproofing is causing major structural damage to the concrete structural slab below these areas,” the report said.

The firm recommended that the damaged slabs be replaced in what would be a major repair.

Some of the damage to the concrete in the parking garage was minor, while other columns had exposed and deteriorating steel work. It also noted that many of the building’s previous attempts to fix the columns and other damage with epoxy were marred by poor workmanship and were failing.

Beneath the pool deck “where the slab had been epoxy-injected, new cracks were radiating from the originally repaired cracks,” the report said.

These were all problems that should have been dealt with quickly, Gregg Schlesinger, an attorney specialising in construction defects and a former construction project engineer, said.

“The building speaks to us. It is telling us we have a serious problem,” Mr Schlesinger said.

“They (building managers) kicked the can down the road. The maintenance was improper. These were all red flags that needed to be addressed. They weren’t.”

Failure to replace “the waterproofing in the near future will cause the extent of the concrete deterioration to expand exponentially”.