Underground garages enrich developers, but create expensive problems for homeowners

No one in South Florida has a basement. So why, with the water table just a few feet below the surface, do developers build underground parking garages, structures that require expensive maintenance and leave a building vulnerable to deterioration?

The answer is money. Shoving all the parking underground allows builders to devote their project’s above-ground floors to condos they can sell.

This decision to squeeze in the maximum number of condos leaves future owners with the formidable and expensive problem of defending their underground garage against water, a notoriously difficult challenge in South Florida and one made even tougher by rising sea levels. Exhibit A is the collapsed building in Surfside , where the underground garage suffered from extensive water damage, with cracked concrete and new cracks radiating from failed repairs.

The extent to which garage damage may have contributed to the collapse of Champlain Towers South remains unknown, with experts saying the investigation will take months.

But a 2018 engineer’s report , which has gained attention as a warning to the Champlain condo board about the building’s troubles, found “abundant cracking” in the garage’s concrete columns, beams and walls. The report found that previous repairs had been ineffective, with new cracks radiating from “repaired” cracks. The threats didn’t all result from the garage’s below-ground location, with much of the blame falling on faulty waterproofing above the garage, where a slab was laid flat rather than sloped to get rid of rainwater, requiring an “extremely expensive” repair.

John Turis, a Champlain Towers South owner who was at his New York home during the June 24 collapse, said there was always water on the garage floor, which the building’s managers tried to dry out with huge portable fans.

“My wife used to always point it out — ‘Why is there always water on the floor?’” he said. “I never gave it much thought, I’ll be honest with you. It wasn’t through the whole garage. It was just some water here, some water there. It was never flooded. I used to put a cover on my car, and whenever I came back, the cover always seemed to be wet.”

A drive along South Florida’s walls of high-rises on State Road A1A shows many condo towers served by above-ground parking garages, with a smaller number of underground ones. Underground garages are especially prevalent in hotels and condos along the oceanfront in Surfside and Miami Beach.

The garages typically don’t go deep, reaching one or two levels underground. The deepest is under construction at Una Residences in Miami, a 47-story luxury building where the garage is planned to go three levels underground, reaching 50 feet below sea level and and containing spaces for 236 cars.

Such designs allow developers to maximize earnings by devoting as much above-ground space as possible to condos.

“It becomes a money game,” said Cesar Soto, a structural engineer and principal of Paramount Consulting & Engineering of Miami. “If you have a tight site plan or floor plan, you want to get as many units as you can. You cannot have on-ground parking because that will limit the amount of units that you can have. He’ll need his money at the end of the day. That’s exactly what it is, money.”

Joel Figueroa-Vallines, president of SEP Engineers, who is involved in the Surfside investigation, said he thinks underground garages make little sense in South Florida.

“When you have a high water table, you generally try to stay away from it,” he said. “That’s why there are no basements in Florida for the most part. The soil is very soft. When the soil is soft and it gets saturated, you get a fluid pressure against the walls and against the bottom of the concrete floors. When I design something here, I advise clients and owners against it.”

Water damage in the Surfside parking garage may have been a “contributing factor” to the collapse, he said. “How much it contributed, whether it was one-tenth of one percent or 10 percent, it’s too early to say,” he said.

Other experts say underground garages can be perfectly sound even in South Florida, provided they’re properly built and maintained against the inevitable assault from water.

“Think of concrete like a sponge,” said Daniel Lavrich, a structural engineer who chairs the Broward Board of Rules and Appeals, which enforces the building code. “It absorbs water. And a certain amount of that water will go into the concrete and eventually reach the reinforcing steel. And if there’s a high salt content, that salt content is going to attack the reinforcing steel even more than the water. When it rusts, it expands, when it expands, it cracks the concrete. That lets more water in, you get more rust, you get more expansion, and on and on.”

Such deterioration can be addressed through regular maintenance, he said, and doesn’t indicate that underground parking garages are a bad idea in South Florida.

“There are certain issues that take place in parking garages relating to cracking of concrete, rusting of reinforcing bars, but most of the time they’re not terribly graphic,” he said. “They need to be repaired, they need to be maintained. It’s the nature of concrete. We use concrete on bridges and piers and sea walls, where they’re actually immersed in seawater, and they have to be repaired, they have to be maintained because they are highly susceptible.”

But maintenance can be expensive, he said. Waterproofing on a deck above a garage requires a membrane that typically lasts eight to 10 years, he said.

“They’re expensive to replace because you have to tear off everything that’s on top of them to get down to the waterproofing,” he said.

And below ground, the garage would require waterproofing along the sides and floor — also expensive to replace because the waterproofing has to be installed on the outside.

Soto, the Miami engineer, said the right waterproofing, properly maintained, can protect underground garages. The outer part of an underground garage is typically wrapped in a waterproof substance such as bentonite, a clay-like material that expands to fill cracks in concrete. This impermeable “balloon,” however, requires maintenance to prevent damage or the need for costly overhauls.

“Bentonite goes into the cracks and seals the cracks so water can’t come in, so it can protect the rebar and the concrete,” he said. “But if you leave these cracks unattended, that bentonite dissipates and then you start getting trouble. So a properly designed system can last you up to 20 years; with good maintenance it can go longer. It can last you 30 or 40 years.”

But he said it’s up to the construction team to do it right because government oversight is uneven.

“How many of those city officials are actually looking at the geotechnical study to see how high is the water table?” he asked. “How many of those city officials are actually questioning if they have the proper waterproofing? There are some building officials and city officials that are very savvy when it comes to this. There are some others that I don’t know. The problem is they’ll just show on a drawing a line that says ‘waterproofing’ and that’s it, that’s enough and that’s it.”

Fort Lauderdale building official John Travers said the city relies on the expertise of the construction team building the project to determine its durability, he said, since the city doesn’t have the personnel or expertise to check every point of its design.

“I understand everyone’s concerned about this, but I’d just like to let you know that we’re very diligent about what we do, very serious about what we do,” he said. “But my plan review team and my inspection team, they’re not engineering experts. We leave it up to the industry itself.”

“The state of Florida certified engineers and certifies architects under two different statutes,” he said. “Those are the licensed people that design, and it’s our job to look at what they design, see if it falls within the parameters of what’s required in our Florida building code.”

At Savoy East, an eight-story condo building in Pompano Beach, owners said they’re having to pay for repairs to their leaky garage, where a cracked slab under the garage has let in the water.

“We’ve got a big hole in there,” said Al Infande, a resident. “It’s only about a couple inches of water. But there’s no telling how the building’s doing with the water running through underneath. I’m concerned.”

Robert Shanahan, a former president of Savoy East, said “typical condo crybabies” are making too much of the building’s garage issues. There is a second garage residents can use, he said.

“If you park your car down there,” he said of the garage with the cracked slab, “you’re probably going to get a lot of mold.”

Rising sea levels, which are having a wide-ranging impact on coastal South Florida, are worsening the pressure on underground garages.

“With sea level rise, the water table is going to rise, and there will be more pressure on these underground systems, with high potential for leaking of that salty water into those facilities,” said Jayantha Obeysekera, director of the Sea Level Solutions Center at Florida International University and former chief modeler for the South Florida Water Management District. “If sea level rises one foot, the water table will also rise by that amount.”

Now that we know sea level is rising, he said, underground garages and other structures should be built in such a way that takes into account future sea levels.

“They should be designed for future conditions,” he said. “If the building is designed for 50 years, what will the water table be like in 50 years, and incorporate that into the design of the structure. Typically, you look at above-ground facilities, like wind damage, but we need to start looking at below-ground facilities as well.”

Staff writer Brittany Wallman contributed to this report.

David Fleshler can be reached at dfleshler@sunsentinel.com and 954-356-4535.