The month of May has the dubious distinction of being the most active tornado month. According to the National Weather Service, the record was set in May 2003, with 543 confirmed tornadoes. The most inherent danger to people and property during tornadoes is the debris carried in the high winds. Enter concrete homes.

Tests comparing the impact resistance of residential concrete wall construction to conventionally framed walls reveal that that concrete homes have the strength and mass to resist the impact of wind driven debris.

To duplicate tornado-like conditions, researchers at the Wind Science and Engineering Research Center at Texas Tech University shot wall sections in a laboratory with 15-pound 2 x 4 lumber “missiles” at up to 100 mph, simulating debris carried in a 250-mph wind.

This testing covered the maximum wind speed generated in 99 percent of U.S. tornadoes. Wind speeds are less than 150 miles per hour in 90 percent of tornadoes.

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 (as depicted in the image to the right): drywall, fiberglass batt insulation, plywood sheathing, and exterior finishes of vinyl siding, clay brick, or stucco.

The concrete wall systems suffered no structural damage during the tests. However, the lightweight steel and wood stud walls offered little or no resistance. In some instances, the debris “missile” perforated completely through the wall.

Concrete homes meet both of the criteria needed to protect occupants in a deadly tornado—structural integrity and missile shielding ability.

For more information on the research from the Wind Science and Engineering Study, click here.

Seeing is believing. An 8-minute video shows the wall tests, providing visual evidence of concrete’s resistance to wind-driven debris—the biggest threat to lives and property in tornadoes. Copies of the video, Built-in Safety, are available from the Portland Cement Association by phone at 800.868.6733 or online at www.cement.org/bookstore. (Note to editors: Broadcast-quality Beta-cam SP versions of the tape are available free to media by contacting PCA media relations at newsroom@cement.org).

For more information on building concrete homes, visit www.concretehomes.com or call the concrete home hotline toll-free at 888.333.4840.


About PCA
Based in Skokie, Ill., the Portland Cement Association represents cement companies in the United States and Canada. It conducts market development, engineering, research, education, and public affairs programs.