Concrete Homes - What the Research Says

Wind Testing Shows How Concrete Walls Hold Up in a Hurricane

one story flat roofed concrete home with shutters behind a short wall near a flowering bush
Local Concrete House Built to Resist Typhoons, Yaeyama Islands, Ishigaki, Japan. Eric Lafforgue/Art In All Of Us/Corbis via Getty Images (cropped)

When hurricanes and typhoons howl, the greatest danger to people and property is flying debris. Carried at such intense velocity, a 2 x 4 piece of lumber will become a missile that can slice through walls. When an EF2 tornado moved through central Georgia in 2008, a board from an awning was ripped off, took flight across the street, and impaled itself deep into an adjacent solid concrete wall. FEMA tells us this is a common wind-related event.

Researchers at the National Wind Institute of Texas Tech University in Lubbock have determined that concrete walls are strong enough to withstand flying debris from hurricanes and tornadoes. According to their findings, homes made of concrete are much more storm-resistant than houses constructed of wood or even wood studs with steel plates. The ramifications of these research studies are changing the way we build.

The Research Study

The Debris Impact Facility at Texas Tech is well-known for its pneumatic cannon, a device capable of launching various materials of different sizes at different speeds. The cannon is in a laboratory, a controlled environment,

To duplicate hurricane-like conditions in the laboratory, researchers shot wall sections with 15-pound 2 x 4 lumber "missiles" at up to 100 mph, simulating debris carried in a 250 mph wind. These conditions cover all but the most severe tornadoes.

Hurricane wind speeds are less than the speeds modeled here. Missile tests designed to demonstrate damage from hurricanes use a 9-pound missile traveling about 34 mph.

Researchers tested 4 x 4-foot sections of concrete block, several types of insulating concrete forms, steel studs, and wood studs to rate performance in high winds.

The sections were finished as they would be in a completed home: drywall, fiberglass insulation, plywood sheathing, and exterior finishes of vinyl siding, clay brick, or stucco.

All of the concrete wall systems survived the tests with no structural damage. Lightweight steel and wood stud walls, however, offered little or no resistance to the "missile." The 2 x 4 ripped through them.

Intertek, a commercial product and performance testing company, has also done research with their own canon at Architectural Testing Inc. They point out that the safety of a "concrete home" can be deceptive if the house is built with unreinforced concrete block, which offers some protections but not total.

Recommendations

Reinforced concrete homes have proven their wind-resistance in the field during tornadoes, hurricanes, and typhoons. In Urbana, Illinois, a home constructed with insulating concrete forms (ICFs) withstood a 1996 tornado with minimal damage. In the Liberty City area of Miami, several concrete form homes survived Hurricane Andrew in 1992. In both cases, neighboring homes were destroyed. In the fall of 2012, Hurricane Sandy blew apart the older wood construction homes on the New Jersey coast, leaving alone the newer townhouses built with insulating concrete forms.

Monolithic domes, which are made of concrete and rebar in one piece, have proven especially strong. The sturdy concrete construction combined with the dome shape make these innovative homes nearly impervious to tornadoes, hurricanes, and earthquakes. Many people cannot get over the look of these homes, however, although some brave (and wealthy) homeowners are experimenting with more modern designs. One such futuristic design has a hydraulic lift to actually move the structure below the ground before a tornado strikes.

Researchers at Texas Tech University recommend that houses in tornado-prone areas build in-residence shelters of either concrete or heavy gauge sheet-metal. Unlike hurricanes, tornadoes come with little warning, and reinforced interior rooms can offer more safety than an exterior storm shelter.

Other advice researchers offer is to design your home with a hip roof instead of a gable roof, and everyone should use  hurricane straps to keep the roof on and the timbers straight.

Concrete and Climate Change — More Research

To make concrete, you need cement, and it's well-known that the manufacturing of cement releases great amounts of carbon dioxide into the atmosphere during the heating process. The building trade is one of the largest contributors to climate change, and cement makers and the people who purchase their product are some of the largest contributors to what we know to be "greenhouse gas pollution." Research on new production methods will no doubt be met with resistance from a very conservative industry, but at some point consumers and governments will make new processes affordable and necessary.

One company trying to find solutions is Calera Corporation of California. They have focused on recycling CO2 emissions into the production of a calcium carbonate cement. Their process uses the chemistry found in nature — what formed the White Cliffs of Dover and the shells of marine organisms?

Researcher David Stone accidentally discovered an iron carbonate-based concrete when he was a graduate student at the University of Arizona. IronKast Technologies, LLC is in the process of commercializing Ferock and Ferrocrete, made from steel dust and recycled glass.

Ultra-high-performance concrete (UHPC) known as Ductal® has been used successfully by Frank Gehry in the Louis Vuitton Foundation Museum in Paris and by architects Herzog & de Meuron in the Pérez Art Museum Miami (PAMM).

The strong, thin concrete is expensive, but it's a good idea to watch what the Pritzker Laureate architects are using, as they are often the first experimenters.

Universities and government entities continue to be the incubators for new materials, researching and engineering composites with different properties and better solutions. And it's not just concrete — the U.S. Naval Research Laboratory has invented a glass substitute, a transparent, tough-as-armor ceramic called spinel (MgAl2O4). Researchers at MIT's Concrete Sustainability Hub are also concentrating their attention on cement and its microtexture — as well as the cost-effectiveness of these new and expensive products.

Why You Might Want to Hire an Architect

Building a home to withstand nature's fury is not a simple task. The process is neither a construction nor design problem alone. Custom builders can specialize in insulated concrete rorms (ICF), and even give their end-products safe-sounding names like Tornado Guard, but architects can design beautiful buildings with evidence-based material specifications for builders to use. Two questions to ask if you are not working with an architect are 1. Does the construction company have architects on staff? and 2. Has the company financially sponsored any of the research testing? The professional field of architecture is more than sketches and floor plans. Texas Tech University even offers a Ph.D. in Wind Science and Engineering.

Sources

  • Inline photo link of Georgia tornado by Mike Moore/FEMA Photo
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Craven, Jackie. "Concrete Homes - What the Research Says." ThoughtCo, Nov. 21, 2017, thoughtco.com/concrete-homes-what-the-research-says-175900. Craven, Jackie. (2017, November 21). Concrete Homes - What the Research Says. Retrieved from https://www.thoughtco.com/concrete-homes-what-the-research-says-175900 Craven, Jackie. "Concrete Homes - What the Research Says." ThoughtCo. https://www.thoughtco.com/concrete-homes-what-the-research-says-175900 (accessed December 13, 2017).