By Melissa J. Buchanan
CEG MANAGING EDITOR
It takes a resilient community to overcome the devastation of a 157-mile per hour (253 kph) tornado. The residents of Tarrant County Texas are rallying together in a massive clean up after a twister ripped apart homes and businesses, and disrupted the lives of thousands. The tornado, which touched down the evening of Tuesday, March 28, 2000, swept though Fort Worth, Arlington and surrounding areas. The Fort Worth Chapter of the Associated General Contractors (AGC) has been in “rescue mode” ever since.
“We’ve already lined up a lot of help,” said Jack Baxley, executive director, Fort Worth Chapter of AGC. “Members are out helping at some of the area schools with roofing and general repairs. City crews and members are really pulling through.”
The damage in Tarrant County was projected to top $450 million, reported the Associated Press. At the time of the interview, downtown Fort Worth was sealed off while workers sifted through the debris and cleaned shattered buildings. Baxley said the association and its members were gearing up for the opening of the downtown corridor, which was expected the morning of April 3. AGC’s Fort Worth Chapter, the Highway, Heavy, Utilities & Industrial Branch and the Dallas Chapter are working together to ease the strains of this tragedy. Baxley said a number of businesses have donated equipment or offered the equipment at a substantial discount.
“We’ll do everything we can to help our community pull back together,” he said.
With so much damage, many have been asking what, if anything, could have been done to prevent such loss.
Federal Emergency Management Agency (FEMA) Director James Lee Witt recently announced recommendations homeowners, businesses, and communities can take to help reduce the devastating effects of high winds associated with tornadoes.
The FEMA study concludes that damage to residential structures could often be reduced or avoided if newer building codes and engineering standards that provided better guidance for high wind events had been adopted, followed and enforced. Many building failures could been avoided with better construction techniques and building materials.
Proper construction techniques and materials based on the most current model building codes can be used in new construction and added to existing construction to reduce the damage from low to moderate intensity tornadoes.
One option is the use of insulating concrete form (ICF), or forms for poured concrete walls, that stay in place as a permanent part of the wall assembly. The forms, made of foam insulation or other insulating material, are either pre-formed interlocking blocks or separate panels connected with plastic ties. The left-in-place forms not only provide a continuous insulation and sound barrier, but also a backing for drywall on the inside, and stucco, lap siding, or brick on the outside.
Within these two basic ICF types, individual systems can vary in their design. “Flat” systems yield a continuous thickness of concrete, like a conventionally poured wall. The wall produced by “grid” systems has a waffle pattern where the concrete is thicker at some points than others. “Post and beam” systems have just that – discrete horizontal and vertical columns of concrete that are completely encapsulated in foam insulation.
Whatever their differences, all major ICF systems are engineer-designed, code-accepted, and field-proven, according to the Portland Cement Association.
Since ICF walls are tornado, hurricane, flood and fire resistant, the material is commonly used to construct safe rooms and shelters. If the safe rooms are constructed to certain performance criteria, the structures are expected to withstand the effects of the high winds and debris generated by tornadoes. (see Sidebar 1)
These performance criteria, according to FEMA, are to be used by design professionals, shelter manufacturers, building officials, and emergency management officials to ensure that shelters constructed in accordance with these criteria provide a consistently high level of protection.
Emgee Construction, a Hurst, TX-based general contractor, specializes in buildings made from IFCs.
“This new generation of building allows us to build quicker and faster,” said Tom Hughes, project manager, Emgee. “The concrete stacks up quickly because there’s no pouring.
“We’re starting to see that the energy savings are significant, and the insurance savings are increasing – a monthly savings of 20 percent,” he said.
Emgee builds storm safe rooms for $4,000 to $6000. These rooms can be added to or retrofitted in a house.
ICF homes can be designed in any style, and will accept any traditional exterior finish including vinyl or wood siding, stucco and brick. ICF systems accommodate the popular design features, such as tall walls, large openings, long floor spans, and cathedral ceilings.
Dick Whitaker, president, Insulating Concrete Form Association, said the ICFs are very efficient to build with and easy to use.
“It’s a very well insulated wall, so you have to compare it to another well insulated wall,” he said. “The cost of building an ICF house is comparable to that of an ordinary 2x6 wood-framed house.”
For more information on the ICFs, contact the Insulating Concrete Form Association at 847/657-9730.
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