ICF FAQ 

Q: What are Insulated Concrete Forms?

A: Insulated Concrete Forms (ICFs) are hollow blocks or panels made of expanded polystyrene (EPS) that construction crews stack into the shape of the exterior walls of a residential or commercial building. Reinforcing steel is than added and the gap between the two layers of foam is filled with concrete, which cures and hardens into a monolithic core. The EPS stays in place. This combination of concrete, steel and foam creates an incredibly strong and energy-efficient structure.

Q: How does the homeowner benefit from this type of construction?

A: Homes built with ICFs offer resistance to natural disasters such as tornadoes, hurricanes, earthquakes, fires and floods. This type of home can dramatically reduce heating and cooling costs, plus provide an exceptionally comfortable and quiet indoor environment without drafts, bugs or mould.

Q: Does it cost more to build this way?

A: Typically, a home built with ICFs will cost slightly more than a comparable wood-frame home. However, much or all of this cost can be recouped through significantly lower utility and energy bills, insurance savings and downsizing of heating and cooling equipment. An experienced ICF contractor may be able to further reduce the costs of construction and bring it very close to conventional wood construction.

Q: How much money can I expect to save on my heating bills?

A: A study commissioned by the Portland Cement Association concluded that homes built with ICF exterior walls offer up to a 32-71 percent savings for heating and cooling costs over comparable wood-frame houses. This means that a typical 2,450-square-foot home in Ontario can save approximately $2000 in heating and airconditioning costs each year. The larger the house, the larger the potential savings.

Q: How well do ICF walls hold up in a fire?

A: 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 Fahrenheit — far hotter than a typical house fire. In “firewall” tests ICF walls were subjected to continuous gas flames and temperatures of up to 2,000°F for as long as four hours. None of the ICF walls ever failed structurally, in contrast to wood-frame walls, which typically collapse in one hour or less.

Q: What is the average R-value of ICF walls? 

A: Walls made of Insulated Concrete Forms are rated on average, like a wood-frame wall constructed with R-25 insulation. But 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 to 40 percent of the heat load requirements of a wood-frame building. ICFs eliminate this air infiltration through the wall assembly. 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-40 to R-50 — or more in some areas of the country.

Q: Won’t the foam burn or give off harmful emissions?

A: The foams in ICFs are manufactured with flame-retardant additives. The National Research Council reviewed the numerous existing studies of fire emissions and concluded that the emissions from polystyrene foams are no more toxic than those of typical softwoods used in home construction.

Q: What about comfort?

A: Concrete walls built with ICFs effectively buffer a house’s interior from the outdoors. The thick ICF sandwich of a massive material (concrete) with a light one (foam) sharply cuts fluctuations in temperature, air infiltration and noise. ICFs keep the inside more comfortable and less drafty than ordinary wood-frame walls. With regard to noise, studies have shown that compared to a typical wood-frame house, only about one-third as much sound penetrates an ICF wall.

 Q: How do Insulated Concrete Form homes resist tornado and hurricane-force winds?

A: Debris driven by high winds presents the greatest hazard to homeowners and their property during tornadoes and hurricanes. Recent laboratory testing at Texas Tech University compared the impact resistance of residential concrete wall construction to conventionally framed walls.

Only concrete wall systems, such as ICFs and concrete masonry, successfully demonstrated the strength and mass to resist the impact of wind-driven debris. The wood-frame walls failed to stop the penetration of airborne hazards.

Q: How popular is this building technique?

A: ICF construction continues to grow at an impressive rate. It is estimated that in 1998, nearly 20,000 homes in the U.S. were constructed with ICFs. It is anticipated that soon more than 100,000 homes will be built annually with ICF exterior walls.

Q: Is this building technique approved by building codes?

A: Yes. Every major code organization in the United States and Canada has accepted this construction technique. ICF homebuilding has proven successful in every region and climate. The 2000 and 2003 International Residential Codes have a section on ICF construction.

Q: Is it difficult for subcontractors to work with this material?

A: No. Subcontractors — such as electricians, plumbers and drywallers — can easily adapt to working in a house with ICF walls. Once they are familiar with the product, many tradespeople actually find it easier than working on a wood-frame home.

Q: Will it take longer to build my home with Insulated Concrete Forms?

A: Experienced ICF crews report that building ICF homes can actually take less time than using wood-frame construction. The ICF construction method eliminates several steps — such as sheathing, insulating and vapour barriering the exterior walls — that are necessary with wood-frame construction.

Q: Can radius and angled walls be constructed with ICFs?

A: Pre-formed 90 and 45-degree corners are available to speed construction since they are the most commonly used corner angles. Radius walls are easily constructed by miter-cutting the form at the proper angle and using foam to join the edges. Some manufacturers will deliver already curbed walls.

Q: Can I leave ICF Block exposed to ultraviolet rays for extended periods of time?

A: Exposure of up to a year should not pose a serious problem. However, a light oxidation layer will develop on the surface of the forms after extended periods of exposure. This oxidation does not indicate any detrimental effects to the wall form. However, if the proposed finish is to be stucco (or another hard-coat material), it requires the oxidized layer to be brushed away to provide a clean bonding surface.

Q: When building with ICFs, will mold and mildew in my new building be a problem?

A: ECO-Block ICFs can significantly contribute to a mold-free environment due to the inorganic nature of the material. They also create a very tight building envelope, reducing unintentional air infiltration. In high-humidity environments, interior moisture should then be controlled through the use of spot removal (e.g., bathroom fans) and properly sized air conditioning units that will cycle on long enough to dehumidify the air.

Q: How does the homeowner benefit from this type of construction?

A: Homes built with ICFs offer resistance to natural disasters such as tornadoes, hurricanes, earthquakes, fires and floods. This type of home can dramatically reduce heating and cooling costs, plus provide an exceptionally comfortable and quiet indoor environment without drafts, bugs or mould.

Q: Can anyone do it?

A: This is not a "Do-It-Yourself" job. Putting the ICF formwork together is easy enough for anybody who has read the manual and achieves a shared understanding of all the sections. However, the ICF form bracing and the concrete pouring is much more demanding. Those sections should be performed by an experienced builder.

Q: What can you build with Insulated Concrete Forms?

A: Cast in place concrete walls for bearing and non-bearing walls that have superior insulation built-in. You can use ICFs for foundations, exterior above grade walls, sound walls, residential, commercial, and industrial walls, retaining walls and radius walls.