Tornadoes, hurricanes and termites are just some of the reasons for building a strong precast concrete home.
By Sue McCraven
Is a precast concrete home measurably different from everything else in the homebuilding market? Can a strong case be made for the advantages of precast concrete compared with more conventional wood-framed or concrete block construction? The most credible answer is found by examining the facts.
Evidence for building a solid precast concrete house is presented by the project architect and engineer, the builder and the precast producer of a beautiful coastal residence in Florida. Exhibits, pro and con, for a precast concrete home can help a prospective homeowner in making the best decision.
Precast exhibits: from the creepy to the explosive
Exhibit A: Storms. Bad weather makes the strongest case for a precast concrete home. The frequency of billion-dollar disasters caused by tornadoes, hurricanes and flooding is depicted in the map from the National Climate Data Center (see facing page). It’s clear that no matter where you build a home in North America, you can benefit from the storm resistance of precast concrete walls.
Exhibit B: Bugs – the destructive kind. From the invasive carpenter ants of U.S. and Canadian northern forests to the ever-hungry termites of more temperate southern regions, a precast concrete home is the best defense against residential insect infestation. Because most homes are built with wood framing, carpenter ants and termites cause billions of dollars in damages annually – more destruction than that caused by all other natural disasters.1
Exhibit C: A 2 x 4 traveling at 296 mph. Lab testing mimics the explosive force of projectiles driven by the very worst storms. “We’ve had more than enough experience with hurricanes and tornadoes to understand the severe damages to homes from high winds and driving rain,” says John Blanchard, general manager of Quick Wall, a division of Manning Building Supplies in Lakeland, Fla. “Our 5-in. or thicker insulated precast concrete walls use 7,400 psi, self-compacting concrete that is resistant to water penetration as well as damage from flying projectiles during storms, and we can back up these claims with results from a certified testing lab. In addition, our precast wall product has an insulation R-value of 8 and a fire-resistance rating of 1 inch per hour.”
Exhibit D: Freedom of design. While a precast concrete home is resistant to insect attack, Les Thomas, an architect in St. Augustine, Fla., has discovered important advantages from an architect’s point of view. “Round windows and curved wall panels are some of the design options that are afforded by precast concrete,” says Thomas. “The precast system is especially well suited for coastal style homes, because it allows us to angle a house against strong winds while opening it up to the best ocean views for the owner.” Tight tolerances, a home that fits together perfectly and rapid construction are important advantages, but the building site must be accessible by crane for erecting the precast panels.
Exhibit E: Engineers like rapid construction and durability. For Bill Freeman of Freeman Design Group Inc., Lake City, Fla., the precast concrete home in St. Augustine’s Davis Shores was his first experience with a precast design. “The biggest advantage of the Quick Wall system in my opinion is the speed of construction,” says Freeman. “With more than 15 years of structural engineering experience in precast concrete, Ron Devlen, P.E., of Devlen Engineering Inc. in Lake Mary, Fla., said, “All engineers understand that a plant-produced product will offer much tighter tolerances than any system constructed at the job site,” says Devlen. “The most important asset of precast concrete walls is durability.”
Exhibit F: Finding a contractor who understands precast. “The greatest challenge when building a precast home in an established residential community is accessibility for the large transport trucks and the 200-ton mobile crane used to ‘fly’ the panels into position,” said John Valdes of John Valdes & Associates, St. Augustine, Fla. “Precast concrete homes, in my opinion, if designed and built correctly, are the answer to storm wind resistance.” Valdes says that contractors seem averse to anything ‘new,’ which to builders can mean “untested, an expensive learning curve, risk, liability and potential loss.” To counter this natural aversion to something new, the precast industry has work to do. Precasters need to educate contractors and address any hesitation to building with a new system by providing everything from engineering assistance and an experienced erection crew to information on precast concrete’s advantages and how rapidly built homes translate into more jobs completed and higher profit.
Exhibit G: The happy precast concrete homeowner. Bill and Shelley Desvousges, who have lived in their Pelican Reef home for more than a year, said, “We knew we wanted to build a precast concrete home, but we were surprised on so many levels. It’s not just the solidity and security of our home, but even with lots of windows, it is cozy and quiet – we actually have to look outside to see if it’s raining.” Precast concrete was less expensive than a concrete-masonry-unit home, and the Desvousges wanted to feel confident in the security of their dream home during hurricane season.
Sue McCraven, NPCA technical consultant and Precast Solutions editor, is a civil and environmental engineer.
1 Source: http://bct.eco.umass.edu/publications/by-title/controlling-termites-and-carpenter-ants/