Aug 22, 2008 9:21 pm US/Central
Concrete Homes Offer Safety, Energy Efficiency
(WCCO)
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The homes start out with Styrofoam building blocks that are then filled with concrete to form walls that are six inches thick.
CBS
The tornado that tore through Hugo was estimated to have had winds between 135 and 165 miles an hour. It's hard to imagine any home being able to withstand that, but there are certain homes that are built to withstand winds of up to 250 miles an hour. They are called
Insulating Concrete Form, or ICF homes.
The homes start out with Styrofoam building blocks that are then filled with concrete to form walls that are six inches thick.
"The blocks are stacked similar to a Lego fashion. Then what we do is we lay rebar inside the wall and then that cavity is filled with concrete, so we get a six-inch reinforced wall that goes all the way up to the roof," said Allan Breidenbach of
AJ Wismin Homes. Breidenbach has been building ICF homes for about five years.
"ICF homes perform really well in extreme climates. So if it's hot it performs well and if it's cold it performs well," he said.
ICF homes are popular in Arizona and becoming increasingly popular in Minnesota.
"This is about 1,854 square feet, and we estimate that'll be about $15 a month to heat and cool the house year round," said Breidenbach.
The Styrofoam keeps the concrete at a constant temperature.
"The concrete goes all the way down to the footing and that footing stays at the constant temperature of the earth. Because of that, the wall then inside that insulation stays that same temperature all the way up," he said.
Insulation is rated according to its R-value, or it's resistance to heat loss. The higher the R-value is, the higher the insulating value.
The walls of a typical home in Minnesota have an R19 value. Breidenbach says the walls of an ICF home are consistently R50.
On the inside of the home there are a couple of other differences. The windowsills are much deeper in a concrete home. Homeowners can still hang pictures and mirrors on the walls. In fact there are stud-like systems throughout.
Strength in Storms "All houses have to do to resist the wind in Minnesota is a three-second gust of 90 miles an hour. That's it. If it's higher than that, then it's above the code," said engineering expert Tim Marshall.
ICF homes are built to withstand winds of up to 250 miles an hour. There are plenty of examples of
ICF homes surviving storms across the country.
The
Portland Cement Association put together a video that shows the safety of ICF homes. It shows Engineers at Texas Tech performing tests on a number of homes to see how they would hold up after a wooden 2x4 was fired at them. The idea was to mimic what happens in a tornado.
In traditionally-built homes the two by fours pierce the walls, even when they're covered in brick. When those same pieces of wood are fired at an ICF home, the concrete stops the wood.
Cost Traditionally ICF homes have been much more expensive; something only the wealthy could afford, but that's changing.
According to the
Minneapolis Area Association of Realtors a typical wood construction home costs $169 per square foot.
The concrete home that AJ Wismin is building in Vadnais Heights costs $205 a square foot; $36 more.
Breidenbach says to build the exact same home, but using standard wood construction would only cost $3 less per square foot.
"So if you're building a 2,000 square foot home the overall impact on your budget to switch from exterior framing of sticks to ICF construction would be about $6,000," he said.
To find more information about concrete home builders in Minnesota,
click here.
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