Are Coastal Condo Foundations Safe From Saltwater?

Rising Tides and Saltwater Intrusion
by Travers Hartnett

Since the catastrophic collapse of Champlain Towers South, a high-rise condominium in Surfside, FL, on June 24, 2021, research has been conducted to identify why the structure failed. In 2023, Frederick Bloetscher, Anthony Abbate, and Khaled Sobhan investigated whether rising tide levels could have accelerated corrosion in the Surfside foundation and been a factor in its collapse.

The researchers noted that the foundation of the Surfside condominium, built in 1979, was designed and constructed when mean high tides were considered stable and not susceptible to significant rise. However, sea levels are far from stable today, rising dramatically worldwide, including in Southeast Florida, Broward, and Dade County.

They wanted to know if rising tidal sea levels could have directed corrosive saltwater to infiltrate the Surfside foundation and contribute to its collapse. The report clarifies that saltwater is highly corrosive to concrete reinforcing steel, and frequent wet and dry exposure cycles will result in accelerated corrosion. Prior research found that concrete beams tested after accelerated corrosion can have a mass loss of as much as 50% to 72%.

Their research, titled, Can Sea Level Rise and Accompanying Saltwater Intrusion Contribute to Catastrophic Building Failures, was published in 2023 in the Journal of Engineering and Architecture.

By comparing the elevation of the Surfside foundation to local tides in 1979 and 2021, they concluded that their foundations were likely to have been exposed to regular cycles of saltwater intrusion.

Research results show that the mean high tide on Florida’s East coast has risen substantially over the past 40 years, 5 inches from 1991. Over the same period, the Surfside building substructure, including foundation piles, pile caps, columns, walls, retaining walls, and garage floor slab, “very likely may have been exposed to periodic saltwater intrusion.” They also concluded that the rise in sea level could have been a factor in the collapse of the Surfside building and that further investigation is needed.

While this research report optimistically believes that new construction can remedy the risk of saltwater intrusion by designing concrete foundations with alternative reinforcement materials, such as nonmetallic glass fiber or glass fiber composites, mitigating the risk of intrusion in older tidal-exposed buildings like Surfside will be more challenging.

Sub-structure inspections will require new measures, best practices, and regulations to protect building infrastructure and public safety. Condominiums at risk of saltwater intrusion will likely be subject to new building codes, complex inspections, the cost of new corrosion detection equipment, and the need for additional long-term reserving for repairs. Bloetcher, F., PhD., P.E., Abbate, A., N.C.A.R.B., A.I.A., and Khaled Sobhan, Ph.D., & E.I. Can Sea Level Rise and Accompanying Saltwater Intrusion Contribute to Catastrophic Building Failures (2023). https://jea.thebrpi.org/vol-11-no-1-june-2023-abstract-2-jea Journal of Engineering and Architecture, June 11.

Travers Hartnett serves as CondoExec’s editor-in-chief. He has over 19 years of experience providing insurance risk management services exclusively to Florida community associations. A Certified Employee Benefits Specialist from the Wharton School and formerly a Human Services—Board Certified Practitioner, he has served on multiple boards as a volunteer and President.