What are Insulating Concrete Forms 'ICF'?

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Insulating Concrete Forms (ICFs) are hollow blocks or panels made of plastic foam that construction crews stack into the shape of the exterior walls of a home.  Workers then add reinforcing steel and fill the gap (typically 100-200mm) between the two layers of foam with concrete.  This combination of concrete, steel and foam creates a very strong and energy efficient structure.

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How does the homeowner benefit from this type of construction?

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Homes built with ICFs offer resistance to natural disasters such as cyclones, hurricanes, earthquakes, fires and floods.  An Eco ICF Block home can dramatically reduce heating and cooling biulls as well as provide a comfortable and quiet indoor environment.

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What are the design possibilities and/or limitations with Eco ICF Block?

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Today's concrete homes can be created with virtually any design or architectural feature.  Eco ICF blocks have furring strips every 200mm imbedded in the panel to allow attachment of wood or aluminium siding, brick, stucco and stone on the exterior and drywall or plaster on the interior.  The result is a home that looks like any other structure in the neighbourhood but has all the benefits of solid concrete construction.

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Does it cost more to build this way?

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Typically for a home built with ICF, the costs will be comparable to a wood framed home, however much or all of the upfront cost can be recouped through lower utility bills, insurance savings and downsizing of heating and cooling equipment.  An experienced ICF contractor may be able to further reduce the costs of construction.  Resale is typically 10-15% higher.

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Is Eco ICF Block a difficult system for a builder to learn?

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Conventional home building crews adapt easily to ICF construction.  Most of the work involved draws on standard carpentry skills and tools.  The foam forms are lightweight and power equipment moves the concrete.  Definitely easier on the builder's back than conventional home building.  

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How much money can I expect to save on my utility bills?

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A study commissioned by the Portland Cement Association concluded that homes built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable wood frame houses.  The larger the house, the larger the potential savings.  Some homes are realizing $1000's per year in savings.

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How well do Eco ICF block walls hold up in a fire?

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Experience shows that concrete structures are far more likely to remain standing through fire than are structures built of other materials.  Concrete does not break down until it is exposed to thousands of degrees Celsius which is far more than is present in the typical house fire.  In "firewall" tests, Eco ICF Block walls were subjected to continuous gas flames and temperatures of up to 1,100 degrees Celsius for as long as four hours.  None of the ICF walls ever failed structurally, in contrast to wood frame walls, which typically collapse in an hour or less.

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What is the average R-value of ICF walls?

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Walls made of ICFs perform on an average, like a wood frame wall constructed for 1.5 insulation, however that's not the whole story.  The equivalent R-value performance of ICFs consists of three factors.  First is the R-value of the expanded polystyrene.  Second, the thermal stability of massive concrete walls reduces the temperature fluctuations, and consequently, the heat load requirements that are common to wood frame buildings.  Finally air leakage (infiltration) can account for 20-40% of the heat load requirements of a wood framed building.  ICFs can reduce this air infiltration) can account for 20-40% of the heat load requirements of a wood framed building.  ICFs can reduce this air infiltration by 75%.  As a result, with the combined performance of the R-value of the expanded polystyrene, the stabilizing effects of the thermal mass of the concrete and the reduced air infiltration, ICF walls actually perform as high as R-3.5 plus - or more in some areas of the country.

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Will the foam burn or give off harmful emissions?

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The foams in ICFs are manufactured with flame retardant additives.  These using the 'Steiner Tunnel Method" show that ICF foams allow only about one fifth the flame spread of wood.  The Southwest Research Institute reviewed the numerous existing studies of fire emissions and concluded that the emissions from polystyrene foams are no more toxic than those of wood.