Frequently Asked Questions


A: Insulating Concrete Forms (ICFs) are hollow blocks or panels made of EPS (expanded polystyrene) plastic foam that construction crews stack into the shape of the exterior walls of a residential or commercial building. Workers then add reinforcing steel and fill the gap (typically 100mm to 200mm) between the two layers of foam with concrete, which cures and hardens into a monolithic core. The foam panel stays in place. This combination of concrete, steel and foam creates an incredibly strong and energy-efficient structure.
A: Homes built with ICFs offer resistance to natural disasters such as tornadoes, hurricanes, earthquakes, fires and floods. An ECO-Block home can dramatically reduce heating and cooling bills, plus provide an exceptionally comfortable and quiet indoor environment.
A: Today’s concrete homes can be created with virtually any design or architectural feature. ECO-Block has furring strips every 200mm imbedded in the panel to allow attachment of any finish — such as wood or aluminum 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 neighborhood but has all the benefits of solid concrete construction.
A: Typically, a home built with ICFs will cost the same as a comparable wood-frame home. Savings will be made through significantly lower utility and energy bills and downsizing of heating and cooling equipment. An experienced ICF contractor may be able to further reduce the costs of construction.
A: Conventional homebuilding 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.
A: A study commissioned by the Portland Cement Association concluded that homes built with ICF exterior walls offer up to a 50 percent savings for heating and cooling costs over comparable wood-frame houses. The larger the house, the larger the potential savings. Some homes are realizing $1,000s per year in savings!
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, ECO-Block 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.
A: The 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, 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 at R-3.78 — or more in some areas of the country.
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.
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.
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.
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. In 2005 there was 9.2 million sq meters of ICF wall erected in the USA.
A: For information on finding a contractor in your area, contact your ECO-Block Regional Manager or the ECO-Block corporate office at 021-760-590.
A: Yes. Every major code organization in New Zealand has accepted this construction technique. ICF home building has proven successful in every region and climate.
A: Yes. If properly reinforced, an ICF home can provide significant protection during earthquakes. If you live in an earthquake zone, you should consult a structural engineer to determine what the reinforcement requirements are in your area.
A: In a building’s life cycle (from construction to demolition), the greatest ecological impact is the amount of fuel needed to heat and cool the home. Insulating Concrete Homes are a preferred environmental choice because of significant savings in natural resources needed to maintain a comfortable temperature.
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.
A: Yes. The ECO-Block system for insulating tilt-up concrete panels offers the speed of tilt-up construction with the benefits of an ICF wall. After setting the panels in the form, you install reinforcement and embeds, and place the concrete. Once the concrete achieves the specified strength, the wall is lifted in place and screw-ties directly to the web system on the panel. For each additional inch of concrete penetration, attach 25mm extensions to the web.
A: Not a problem in New Zealand, but if it was Expanded polystyrene (EPS) has no nutritive value to insects, including termites. If left exposed and untreated, they may attempt to nest in the EPS foam. Foam is approved for use below grade, as well as above grade, by all building codes as long as “an approved method” of protecting the foam plastic and structure from termite damage is provided. Deciding what constitutes an approved method, however, is left to local code officials.
One measure agreed upon by all parties is the need for a minimum 6” bare concrete inspection strip at grade level. This is required if foam is used below grade or only above grade. This is extremely easy to accomplish with ECO-Block, since it is a panelized system. A 6” horizontal strip of EPS is cut out to allow the formation of a solid concrete barrier at grade. This creates a solid concrete barrier, forcing the termite to the outside of the foam where it is visible Additional steps, together or separately, may meet the “approved method” requirements:
Protect the foam with a termite barrier made from stainless steel mesh.
Install “bait systems” on exposed concrete strips or treat the soil as usual.
Treat footings and backfill with termiticides.
Eliminate as much wood in the structure as possible by using steel and plastic replacements.
Remember, in a solid concrete home there is little to eat. The concrete also acts as a solid barrier to termite infestation inside the home.
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 and insulating the exterior walls — that are necessary with wood-frame construction.
A: Yes They will ensure that your construction project meets local code requirements as well as ensure proper design loads for hurricanes, earthquakes and other natural environmental conditions. Commercial buildings generally require engineering.
A: Pre-formed 90 and 45-degree corners are available to speed construction since they are the most imagesly used corner angles. Radius walls are easily constructed by miter-cutting the form at the proper angle and using foam to join the edges. See the installation manual for more information.
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.
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.
A: Simply call us at 021-760-590 or e-mail us at You can also submit a question via our contact page.