Recent hurricanes have taught valuable lessons about how we should build our homes.
By Ron Hyink
With the possible exceptions of college football and rum-and-vodka cocktails, the mention of hurricanes in Florida arouses feelings of dread and grief among those who live there. Like the mark of Zorro, multiple major hurricanes slashed across the chest of Florida within a six-week period during the summer of 2004. Hurricanes Charley, Frances, Ivan and Jeanne left behind tens of thousands of wrecked lives and shattered homes in their dark wakes.
For better or worse, these hurricanes have instilled some valuable lessons about how we build our homes. Indeed, the state of Florida upped the ante on its building codes since Hurricane Andrew smashed through the southern tip of the state in 1992, and more than a few home builders were scrambling to live up to those standards. Block construction seemed the logical alternative to timber, but nevertheless the devastating 2004 hurricane season left many contractors reeling under lawsuits and searching for a better way.
But not all builders are up against the litigation wall, because for them precast concrete wall panel manufacturers already had the answer to the question about hurricane-resistant construction. According to some recent laboratory testing, only precast can stand up to that tortuous level of wind and water penetration.
The damage done
“Hurricane Andrew came through and devastated southern Florida,” said Blanchard Blanchard, general manager at Quick Wall, a precast concrete wall panel manufacturer in Lakeland, Fla. Blanchard said that block construction has been used predominantly ever since Andrew at least as far north as Jacksonville, Fla. Then the 2004 hurricane season struck, damaging more than 330,000 homes (see the sidebar “Dark Cloud”).
“There were a lot of problems with moisture and infiltration of water into block, because it’s a dry-cast, porous product,” said Blanchard.
“The winds were so strong, it blew the water through the stucco, through the block and into the house,” said Jeff Carboni, sales manager for Quick Wall. “It was a mystery at first, but then they realized that’s exactly what had happened.” Carboni explained that water penetration was only the beginning, as homeowners ultimately had to deal with mold and rot as well.
“With our product and the self-compacting concrete as dense as it is, there is no penetration of water,” said Blanchard. He is very comfortable with saying that, as he has the certification to back him up. Recently he hauled a sample of his wall panels over to Orlando, Fla., to be tested. “We went to a certified testing lab in Orlando, where not only do they fire 2 by 4s out of a cannon at the product, but they also test it for vacuum and compression to simulate the air pressures when a tornado comes through – because the tornados are what did all the structural damage in this state,” explained Blanchard.
But then something happened at the testing lab that hadn’t happened before: The 2 by 4s could not penetrate the wall, even when the cannon was cranked up to its most powerful setting of 296 miles per hour – zero failure. “Well, we hit that 296 and their machine couldn’t go any further,” said Blanchard, “so at this point we’re certified by the state as an actual hurricane-resistant product.” In addition, Quick Wall passed a four-day water permeation test at the lab. With three separate samples – four days of constant water pressure – the results showed zero water penetration! “We are the first wall system to achieve that combined rating, be it block or precast.”
When Blanchard took his wall panel to the lab, he figured he had a strong product, but he didn’t know exactly what to expect. “Part of our quest was through some research and development testing to find out just how strong their product was,” said Jim Blakely of Certified Testing Laboratories in Orlando, the largest independent family-owned testing operation in Florida. CTL performed some uniform static loading, which duplicates a product in wind shear. “In addition to this, we did the large-missile impact (with) an 8-pound, 9-foot-long 2 by 4 at 50 feet per second shot from 16 feet at the product,” said Blakely. Plus the lab performed uniform static cyclic loading, which duplicates the buffeting effects of a hurricane. The results were impressive – Blakely said the precast panels fared far better than other products he had tested.
So everything we have is certified and tested,” said Blanchard. He has even sent his product to New York to be tested for R value, which resulted in an R-8 rating for a 5-inch panel.
Standing strong against rigorous laboratory testing is the result of solid manufacturing techniques and an average 7,400 psi 28-day compressive strength and a 5-inch-thick insulated wall panel that comes with a 1-inch-per-hour fire rating. But what about the seams?
“We take extra care to make sure that they are completely sealed,” said Carboni. The installation crews use a sealant between the panel and the slab – the same sealant used on underground utility and septic tanks. They then apply a spray foam on the inside and a caulk adhesive on the outside. “And then they do the mechanical expansion joint at each seam with stucco. So all those things combined seal it up watertight.”
Although some builders are complementing the precast concrete wall panels with steel roofs for ultimate durability, most are calling for anchored 2-by-6 planks to be cast into the tops of the panels. That allows them the convenience of anchoring the roof trusses at any break point they desire. Truss straps can also be cast into the product, and some savvy builders are utilizing them to great advantage, but their plans have to be precisely engineered before pouring operations can begin.
Exodus in reverse
Despite the heavy toll the hurricanes exacted in lives and damage, droves of people continue to move into Florida. “There is a statistic that says a thousand people are moving to Florida a day,” said Carboni, and that means more and more residential units will be in demand.
It also means that home builders, who typically require inexperienced block masons to put up a house, will be struggling to keep pace. But precast concrete wall panels equate to a much faster completion time. “We set two houses today; normally it would take that guy two weeks to put up the walls, lintel pours and pass inspections just for one house,” said Blanchard, referring to the typical single-story family dwelling. “The time that we save the customers is time they can put toward building more houses,” said Blanchard.
Time truly is money, and the bigger the house the more the savings. “On a big $6 million house and above, we’ll save a guy 45 days right out the gate,” said Blanchard.
But no matter what a contractor’s timetable is, a sturdier wall system in a fraction of the time can be had, and that makes the total end cost much more attractive – not only for the contractor but for the homeowner as well.
And it’s not only what the contractor gets, it’s what he doesn’t get that carries a lot of appeal. “The primary benefits, for example, are the things that we eliminate: We eliminate the headaches of time, we eliminate the headaches of inspections – our product will eliminate anywhere from three to five inspections that he has to go through,” explained Carboni. He also pointed out that site cleanup is drastically reduced, because the masons and the backfill for the masonry cells is eliminated.
That makes precast wall panel manufacturers well-equipped to deal with the masses.