Insulating Concrete Forms (ICF) are hollow foam blocks made from Expanded Polystyrene (EPS) that becomes the form work for constructing a building’s exterior walls out of concrete. As such, ICFs take the place of traditional concrete forms with an added benefit that they stay in place.
During construction, ICFs are stacked into the shape of the exterior walls of a building. They are then reinforced with steel rebar, and filled with concrete. ICFs, therefore, fuse one of the finest insulating materials, EPS, and one of the strongest structural building materials, steel reinforced concrete, together. ICFs also combine five steps into one:
- Structural strength
- Continuous insulation
- Continuous fastening strips
- Vapor and air barriers
- Sound barrier
ICFs are also easier to install than traditional concrete forms. ICF walls lay out faster, safer, and there is no need to remove the forms or wait long periods of time while the concrete cures. This is called a “moist cure” and does not require the need for additional heating, even in cold weather. As the concrete cures within the ICF, the walls reach strengths of up to 4800 PSI after 28 days and strengths of 8000 PSI after the first year.
Typical ICF performance to wood-frame construction.
|ICF Performance Characteristics||WOOD||ICF||RESULT|
|Building Life Expectancy||80-85 years||200+ years||2-3x longer|
|Insulation type||Fiberglass R-19||Expanded Polystyrene||Higher efficiency|
|R-Value of wall assembly||
|-ASHRAE||R-17||R-20 - R-25||30% higher|
|-Infrared Thermographic test||R-13 to R-15||R-28 to R-50||2-3x higher|
|-Through walls||High||Near-Zero||Virtually leak proof|
|-Entire structure||0.45 to 1.05 Air Chg Per Hour||0.15 - 0.20 Air Change Per Hour||4x better|
|Air changes due to leakage||12-24 times per day||3-4 times per day||4-6x better|
|Mass of 8 ft wall without coverings||32 lbs/ft||440 lbs/ft||14x stronger|
|Heat reservoir||9.2 BTU/hr/deg F||93.0 BTU/hr/deg F||10x greater|
|Flame Spread Index||55-200+ with 100+ being more common||Less than 25||4x safer|
|Carbon Monoxide released in a fire (per ASTM E84)||110 ppm||10 ppm||11x safer|
|Sound insulating qualities||STC 32||STC 51||Virtually sound proof|
|Source: Insulating Concrete Form Association/ 1999 – 2001 Builders Web source/Building Technologies|