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Greg Horstmeier
News Director
573-884-1846
horstmeierg@missouri.edu
Published: May 11, 2006
Story Source: Jeff Barber, (417) 682-3579
OSAGE BEACH, Mo. - When tornadoes were forecast the weekend of March 11-12, building contractor Frank Lee didn't go to the basement of his Camdenton, Mo., farmhouse.
He knew of a safer place.
Three years ago twisters scoured wide swaths of earth not far from his home, leaving scars in the landscape that remain today. This time, Lee wasn't taking any chances in a typical wood-frame home. His parents, children, grandchildren and friends, about 25 people in all, gathered in a vacant three-bedroom concrete home that he recently built. He was still putting the finishing touches on the investment property's interior.
Made of six-inch reinforced concrete walls, it's built to withstand substantially greater sustained winds than building codes require - Lee believes it will handle tornado force winds - and the impact of wind blown objects.
"Any tornado we've had here, this would stand up to it," Lee said.
He built the walls using blocks called insulated concrete forms, more commonly referred to as ICFs.
"ICF construction, while still an exception, is catching on in Missouri," said Jeff Barber, a registered architect and University of Missouri Extension housing and environmental design specialist based in Lamar, Mo.
"In the extension offices, after a tornado hits, we'll spend days, even weeks, answering the question 'What can I do to protect my family against a tornado?' This is one of the things we suggest," Barber said.
Besides being safer, properly designed ICF buildings are more fire resistant, more durable and much more energy efficient, he said.
The reinforced concrete walls are formed by interlocking foam insulated blocks, four feet or more long and a foot or more high. There are interior and exterior foam panels, each 2 to 2.5 inches thick. Between the foam panels typically is a four- to 12-inch core, held together with plastic webbing. The core allows for rebar placement and the pouring of concrete. The foam blocks attach one on top of another like huge Lego blocks.
After the concrete sets, the foam is left in place and can be covered with siding or a variety of other facade materials on the outer walls and wallboard on the interior surfaces, Barber said.
ICF blocks are made by various manufacturers throughout the United States and Canada.
ICF construction is more common in Gulf Coast states. When designed properly, the buildings are able to weather hurricanes, Barber said. Walls are virtually immune to termites and mold, though roofs are usually built with wood and are susceptible to insects.
The ICF method is at least 60 years old, Lee said. It was used by Europeans following World War II because there was little lumber, lots of reconstruction to do and Europeans favor durability in structures, which reinforced concrete provides.
Lee, owner of F&L Enterprises, has been in the construction industry for 25 years and started building ICF homes five years ago. He can build an ICF house at least 25 percent faster than a wood-frame counterpart, he said.
In early May he was constructing two 3,300-square-foot apartment complexes in Osage Beach.
"Normally a building like this would take four to six months to build. We'll do it in three," Lee said. "They are as safe as we can possibly build them."
He plans to build a concrete home for his wife and himself.
Barber estimated that there are dozens of concrete homes under construction at any given time in the state. ICF is even more popular for commercial buildings. Pierce City, Mo., with Barber's assistance while he was in the private sector, replaced its fire station and added a community storm shelter with an ICF building system after a tornado demolished the previous station in May 2003.
"The fire station itself can stand up to F-3 tornados and the shelter F-4 tornado conditions, with winds reaching 200- to 250-mile-per-hour for three-second gusts," Barber said.
Barber is informing builders, code officials, building inspectors and fire protection districts about the technology and also providing a forum for discussion and learning.
"This is one of those things that people might have heard about but want to know more. They need unbiased information to determine myth from reality," Barber said.
A $200,000 wood-frame home built using ICF methods would cost 4 percent, or $8,000 more, Barber said, citing data from the National Association of Home Builders.
"Lumber prices fluctuate wildly after disasters like hurricanes and tornados so it is difficult to pin down actual cost comparisons," he said.
Energy use is typically 30 to 50 percent less in an ICF home. Insurance costs also may be reduced. Because of those factors, Barber said, the difference in total monthly cost to a homeowner is probably negligible.
For more information about ICF construction, Barber can be reached via e-mail at barberj@missouri.edu.
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