Insulated concrete forms (I.C.F. or ICF) are interlocking modular units made of expanded or extruded polystyrene (EPS or XPS) that are dry-stacked into the shape of the exterior walls of your home.  

Reinforcing steel is added and concrete is poured into the ICF forms.  The foam remains in place and becomes part of the wall, thus providing the insulation value to the wall system. 

The result is a home that is comfortable, provides sound absorption, is energy efficient, and has strength, durability and design flexibility.

Energy Efficiency

Houses built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable frame houses.  These are not one-time savings; they continue year after year.

The thermal mass (the ability to smooth out large swings in temperature) of concrete contributes to the reduction in heating and cooling costs.  Since the energy needed to heat or cool is less, the size of furnaces and compressors can be smaller, reducing equipment costs.

The CTL report of February 1, 1996 of 338 cities across the U.S. and Canada gave an equivalent performance R-value of ICF for the City of Ottawa of R-28.7.  The CTL report was based on a wall with a concrete thickness of 5 inches and EPS thickness of 2 inches.  Robro Construction Inc. uses ICF with a concrete thickness of 6 inches and EPS of 2.5 inches which increases the R-value.  For a typical wood frame wall to have the equivalent performance R-value, the R-value of the wood frame wall would have to be greater than R-50.  The R-value of an average wood frame wall ranges between R-9 to R15 (the R-value fluctuates depending on how many windows, doors, storeys, etc.)

Almost half of energy loss can be found through the foundation and above-grade walls.  With an ICF home, the outside wall is continuous from the foundation to the eaves and as floors are hung on the inside, there is no break in the walls as compared to a traditional frame house where there are hundreds of joints between exterior wall studs, floor plates, and windows and door frames.

High Indoor Air Quality

Insulated concrete forms prevent air movement, thus creating an airtight seal around the entire perimeter of the building and preventing the entry of dust, pollens and pollution.  The use of EPS panels also eliminates all airborne glass fibres (commonly found in traditional fibreglass insulation) and insulation settlement caused by fibreglass insulation.

Concrete is inert and non-toxic.  As it is naturally waterproof, it doesn’t need volatile organic-based treatments. No CFC’s, HCFC’s, formaldehyde or any chemicals are used in the manufacturing process and no off-gassing is present.

Reduced Emissions

An ICF home reduces energy consumption on average by 30-50% monthly, which translates to an equivalent reduction in harmful emissions. 

Based on a 100-year life cycle, ICF homes can reduce carbon dioxide emissions by over 100,000 kg, assuming 40 kg/GJ for power generation.  This reduction greatly outweighs the emissions caused by manufacturing concrete, which is estimated at 2,000 kg according to the 1994 study by Forintek.

In building an ICF home, construction waste is typically 2-5%, much less than other wall materials, and benefits the environment by decreasing the waste going to landfills.  Every one tonne of methane gas produced by landfilling practices can be counted as 20 tonnes of CO2 being produced, contributing to global warming.

Strength and Durability

ICF homes are built using reinforced cement.  Reinforced concrete buildings are very strong and are less susceptible to damage caused by the forces of nature such as earthquakes, tornados and hurricanes.

Concrete walls are resistant to rust, rot, burning, light, oxidation and pests.  There are no exterior wall cavities for pests, insects or mould to live in.  ICF walls have little or no maintenance or repair. 

Depending on the type of finished used, ICF walls provide two to three hours of fire protection.  For example, a typical 6-inch concrete wall with a gypsum board interior and a stucco exterior will provide a minimum fire rating of three hours.

ICF homes retain their value for a longer period of time due to the fact they’re sturdier, stronger and require much less repair and maintenance than conventionally built homes.

Comfort

ICF homes have even temperature, fewer drafts, fewer hot and cold spots, and consistent floor-to-ceiling temperatures.

Conventional frame homes carry an STC (sound transmission class) rating ranging from 36-38.  ICF homes carry a sound transmission class (STC) ranging between the high 40s and the low 50s.  As the STC is based on a logarithmic scale, this means that loud sounds such as vehicles, airplanes and trains from outside are reduced to a whisper in an ICF home. 

Awards

• Canadian Home Builders Association Enviro-Home Award

• CMHC Healthy Housing™ Award

• EnerQuality R-2000 Environmental Excellence Award 2000

• Cement Association of Canada, National Outstanding Energy Efficiency Award 2001

Further reading

• www.cement.ca

• www.forms.org

• www.integraspec.ca

Sources

1. Cement Association of Canada

2. CMHC, Research Highlight “Alternative Wall Systems for Low-Rise Housing,” Technical Series 02-132, Oct. 2002

3. Research Highlight "Monitored Thermal Performance of ICF Walls in MURBs," Technical Series 07-119, Dec. 2007

4. Zero Energy Home

5. Insulating Concrete Form Association

6. IntegraSpec®

7. GreenBuildingTalk.com

8. CTL Report dated February 1, 1996