WHY SCREENS FAILED Engineering, inspections inadequate
By TONY DORIS Palm Beach Post Staff Writer
Florida's ubiquitous screen enclosures are tearing apart by the thousands in hurricane winds they are supposed to withstand.
That happened because engineers cut corners to make the structures cheaper and weaker. The problems get worse when contractors scrimp on screws and bracing called for in engineering plans — and building inspectors don't know the difference.
An inquiry by The Palm Beach Post found Florida's screen enclosure industry torn apart by loose regulation and cutthroat competition, and it's costing homeowners millions. With insurance companies covering part of the loss, all homeowners pay through higher premiums.
At least $18 million worth of enclosures were destroyed on the Gulf Coast in last year's hurricanes, an estimated $2 million in Palm Beach County. Losses for this year's storms, still being tallied, are expected to exceed that.
Why so many screen enclosures failed during Hurricanes Frances, Jeanne and Wilma is a closely kept secret within an industry that's largely self-policed. Most of its customers, who typically spent $10,000 or more for insect protection, assume nothing could have saved their pricey enclosures.
In many cases, it didn't have to be that way, experts say; if engineers can design earthquake-resistant bridges, they should be able to devise a screen room that can resist 100-mph winds.
Kicked into action by Frances and Jeanne, a handful of engineers and contractors who specialize in the structures are grappling with the technical challenges. But by and large, a Florida born-and-bred industry of Tin Men is winging it, selling as many enclosures as they can, building as fast as they can and not looking back —
except to replace the units they just built, doubling their money.
"Screened enclosures are going to be the death of me," said Wellington building official Doug Wise. "I think the basic assumptions they're making in these things have to be flawed. . . . The engineers don't know. The contractors obviously don't know. It's a big problem."
During the past 30 years, screened patio and pool enclosures have become hallmarks of Florida's good life, much like the venerable Florida room, a converted carport with jalousie windows, was the must-have luxury of the 1950s.
As more and more newcomers swarmed to Florida, having just a pool wasn't enough. The pool and patio had to be shaded with screening and shielded from mosquitoes. By the 1990s, virtually every major home builder offered enclosures. >From January 2003 through June of this year, 5,328 construction permits were issued for enclosures
in unincorporated Palm Beach County alone.
While pool and patio cages proliferated, the industry went largely self-regulated — and untested by serious storms. But with Florida now in a cycle of more frequent hurricanes, the industry is getting tested, and many of its leaders are quick to admit it is failing badly.
Some blame the building code, saying it's too vague and subject to interpretation by engineers and installers.
Others blame poor engineering. Although the complexity and prestige of designing bridges and condo towers attracted some engineers, others — some are not even trained in structural engineering — have found their niche in enclosure design. Few realized how differently screen cages react to wind than houses do. Until 1999, no
scientific research had been done to determine just how strong the aluminum framing had to be to withstand the wind loads of a hurricane, so the industry accepted the best-guess calculations of engineers, including some quick to please contractors more driven by profit than worry over wind resistance.
Tampa engineer Do Kim, a member of the Florida Building Commission, put it bluntly: "It's bottom-of-the-barrel engineers, trying to tackle a very sophisticated structure."
Hurricane Andrew in 1992 served as a shot across the bow for some engineers, who quickly went back to their drawing boards. But those who insisted on beefy designs found they couldn't compete. One, V. John Knezevich, went from being one of the state's busiest enclosure designers for years to being virtually out of the pool cage
business within months because his newly braced, post-Andrew designs cost 10 percent more to build than his competitors'.
The tall, gray-haired engineer taps a finger on a copy of his 1994 design and points to redundant fasteners and diagonal braces added after Andrew to withstand extreme winds. "This is basically the drawing that put me out of business," he said.
Industry leaders admit that contractors seek out "the man with the span." That's the term they use for an engineer willing to sign off on the longest beams with the least bracing — the cheapest to build, regardless of whether they stand up to 140-mph wind, as the building code has required since 2001.
"We got in that mode for a number of years," said industry veteran Richard Prince, president of Screenco North of Riviera Beach. "I'd talk to a contract manager for a large developer, and he'd muscle me down and say, 'I'd like to use you, but look at this price.' "
Drawings not always followed
That's not the whole problem, The Post found. Quality of engineering aside, many installers don't follow the schematic drawings they receive from the engineers.
So consumers may get bad engineering and bad construction, even as they endure yearlong waits for repairs and new installations, and pay prices three times higher than a couple of years ago.
Michael Sonsini, Palm Beach County chairman of the Aluminum Association of Florida, said the recent spate of hurricanes helped him and his competitors see the light. At an association meeting in November, he made an emotional plea to engineers to come up with clearer, more reliable standards that contractors can abide by to make
Sonsini, after all, had just had a front seat to Hurricane Wilma's devastation. He watched as Wilma whipped across the lake behind his Wellington home and crumpled his own enclosure, despite an upgrade just days before. "I put on the very strongest wind bracing there is, in the history of the business," he said.
The enclosure withstood the leading edge of Wilma's eye wall; the beams flexed, but held. Then the back end of the hurricane buffeted the house. First one aluminum beam bent, then the structure. "I saw it fail," Sonsini said. "My whole screen enclosure came down."
Sonsini's company, Screen Builders, is among the busiest in the state, and has built 69,000 enclosures since 1987, by his estimate. More than a week after the storm, his company's 15 phone lines were still lit up. Answering machines handled the calls because his 14 salespeople were too busy to take them.
Records show that Sonsini's company has hired a string of engineers disciplined for breaking the rules by the Florida Board of Engineers during the past three years, including the one who designed Sonsini's enclosure, Nagendra Khanal.
Asked about the engineers, Sonsini said that, until recently, he thought an engineer was an engineer, and that, if one signed and sealed a drawing, building departments had vetted it properly.
Though business was pouring in faster than his and other companies could handle it, the stress of having seen so much of their work destroyed was evident on the faces of contractors at the aluminum association's engineering design committee meeting in November, soon after Wilma.
After meeting every six weeks for a year, the engineers thought they'd made progress. But there's nothing like the sight of hundreds of new enclosures reduced to wreckage to make a designer question his assumptions.
As David Miller, who co-wrote the association's standards manual, put it: "If you have a thousand enclosures that are designed for 140 mph and the winds blow at 80 or 90 and a large percentage of them fail, there's a problem somewhere."
The working group formed after a Palm Beach County building official made a rare move: He shut down the lucrative industry in the vast unincorporated sections of the county. The official, A. Roland Holt, himself an engineer, instituted a monthslong moratorium on permits for enclosures.
Shocked at how much destruction he saw despite wind speeds lower than the law requires enclosures to withstand, he felt obligated to force the industry to confront the failure, he said. "I squeezed those guys. Put them out of business. There was some motivation for them to make progress to do a better job."
He found many failures occurred because contractors used improper fasteners or failed to anchor enclosures to concrete footings. But in other cases, contractors followed engineers' plans, and enclosures still failed.
The association since has taken its standards up a notch. Those changes to its manual took effect Oct. 1, just weeks before Wilma. Some contractors didn't wait and started building to that level months earlier. But Wilma showed the association that it hadn't gone far enough.
Cost-benefit decisions are central to the issue. How much strength are homeowners entitled to for their money? How much are they willing to pay for more?
"If you think about a screen enclosure, it's there for pleasure — to keep the bugs away. And we're trying to build a bomb tunnel," said Doug Rice, who handles building permits for Screenco North. "It's like asking Ford or Chrysler, 'Build me a vehicle that, when it crashes, it doesn't have any damage.' How do you do
It breaks, but doesn't take the house
Costs and benefits can be moving targets. At the recent association meeting, when chapter president Sonsini griped that the engineers had failed the contractors, engineer Frank Bennardo countered that three years ago, Sonsini wouldn't have accepted the costs of thicker aluminum or the addition of view-blocking braces.
The state building code even acknowledges that pool enclosures don't have to be as strong as a house. That's factored into the load tables engineers use to calculate enclosure dimensions and bracing. Besides, as some contractors like to say, they'd rather have the enclosure break than take the house with it.
Even as they look to beef up designs, some contractors insist they did the best they knew how, against an act of nature.
Sonsini attributed the destruction he saw to "microbursts" of wind, or "tornadic action" that meteorologists and the media didn't report.
Holt, Palm Beach County's former building official, shot back with this definition of a microburst: "A minute tornado embedded in a hurricane that has the ability to rip out a screened enclosure without taking a single tile off the roof — a figment of some screen contractor's imagination."
Another installer, Buchanan Screen and Rail's Steven Raskin, also is convinced that wind speeds were higher than the public realizes. His explanation: Early National Hurricane Center estimates of 120-mph sustained winds, added to the nearly 30-mph forward motion of the storm, put Wilma well over the 140-mph design limits of South
But the latest post-storm calculations from the National Hurricane Center near Miami indicate that Wilma crossed South Florida as a Category 1 hurricane, at 74-95 mph, with possible "spots of Category 2" winds, 96-110 mph, said Richard Pasch, forecaster at the Hurricane Center. Gusts of 120 mph "possibly
occurred," he said.
Those numbers already include the storm's forward motion, he said.
Screens catch wind like sails
How complicated could it be to build an aluminum box with screens attached?
For starters, the screens, particularly densely meshed ones designed to keep out tiny, blood-sucking "no-see-em" bugs, quickly clog with rain and catch the wind like sails. As a result, under hurricane conditions, thousands of pounds of wind pressure slam the enclosure from at least one direction.
A portion of the wind gets through the mesh, exerting more pressure on the opposing walls and top and filling the enclosure like an over-inflated balloon. At the same time, wind passing over and around the structure tugs at it from the far side, like a vacuum cleaner.
The beams and supports up against these forces are built from aluminum alloy little thicker than a credit card, designed for the lowest possible cost and easiest installation. It's a lightweight metal that's easy to work with. Or, as engineer Frank Bennardo of Boca Raton put it, "glorified butter."
Another common problem: support beams attached to or through patio pavers, instead of directly into concrete footings. Many enclosures lifted and blew away because an inch-thick tile won't anchor an enclosure.
Many enclosure walls and tops have too little diagonal bracing. Homeowners don't like views blocked and installers are happy not to spend the extra money. Even with bracing, age and corrosion weaken connections and loosen screws.
The aluminum association's engineering working group, with a consultant from the national aluminum industry, has been trying to come to understand the wind forces at play and to refine the calculations used in the designs. But there has been only one recognized study for them to rely on, a work widely considered competent but
preliminary. With only that 1999 analysis of wind-tunnel tests, engineers and contractors have been left to sort things out on their own, learning by trial and error. Hurricanes are their wind-tunnel tests.
Bennardo, one of the most active members of the group, said the industry's and engineers' knowledge is evolving.
Last year, Bennardo said, he found that angle brackets that hold beams and braces together didn't hold up. So this year, he used stronger angles. This year the angles didn't break, but screws pulled out of the angles. So, he reinforced the metal where the beams hold the screws in place.
"Then we're going to find the next weak point," he said.
Official approval isn't stamp of quality
Many consumers assume a building department's approval means engineers and contractors did a good job. It doesn't.
Local code enforcers generally have little knowledge of the complexities of enclosures. The inspectors check for basics, but with the notable exceptions of Miami-Dade County and the city of Coral Gables, few other local governments have structural engineers on staff to evaluate enclosure designs.
City building officials are frustrated at the number of enclosures toppling every time there's a storm.
"My residents are angry," said Wellington official Wise. "This stuff is failing. Maybe it's a failure of everybody, but I'm not sure our responsibility goes to the level of engineering. This is shaking my foundation, which is: I need to be able to rely on the design professional, that he has designed this thing where
it's not going to fail."
Wise added that his staff saw failures where contractors didn't follow engineers' plans as well as failures where they did.
"The question is, who do I rely on now?" he said.
Palm Beach County, which also has no structural engineer among its 194 building department employees, has opted to pay the aluminum association to analyze designs for it. Those reviews will serve as a backup to county plan examiners who suspect that a submitted master design — the same specifications used over and over — might
be flawed, said building official Rebecca Caldwell. "For a design that has the potential to be reproduced thousands of times in a fast manner, we want a peer review," she explained.
As far as repair standards, Caldwell is making contractors bring older, storm-damaged enclosures up to 75 percent of the strength that is required in a new enclosure. Some contractors question whether they should have to rebuild heavily damaged enclosures even to that standard, but that's what the code requires, she said.
With forecasters predicting a decade or more of frequent, seasonal gales, contractors and engineers clearly are searching for their lost equilibrium.
As contractor Richard Prince left the association meeting, exasperated at Wilma's aftermath, he turned to his longtime engineer, Bill Passinos. "What happened?" Prince said.
Passinos gave the same answer as last year: "It's a hurricane, stupid."