Frequently Asked Questions


Q. Can ICF’s be used both below and above grade?
A. Yes. ICF’s are particularly attractive for lower level living spaces, but above grade they provide benefits simply not available with traditional above grade construction.

Q. How tall can ICF walls be built?
A. ICF’s have been engineered and built to 48 feet in a free standing, load bearing application. ICF walls are designed like any other steel reinforced concrete wall.

Q. What kinds of exterior finishes can be used with ICF’s?
A. Any exterior finish used on other types of construction can be used on ICF walls. ICF’s are particularly cost-effective when EIFs and stucco surfaces are desired, but are receptive to brick, stone, and dimensional siding such as vinyl, aluminum, steel, wood and cement board siding.

Q. What kind of interior finishes can be used with ICF’s?
A. Gypsum board is the most common interior finish over exposed EPS. However hard veneer plaster, earth clay plasters applied over drywall, and interior acrylic stucco can all be applied to ICF’s on the interior.

Q. Do ICF walls sweat?
A. No. The expanded polystyrene panels in an ICF are a poor conductor of heat or cold. As a result, water vapor that may be present within a structure will not condense on the walls.

Q. Is a vapor barrier needed on ICF walls?
A. No. EPS and concrete together act as a natural barrier against air and moisture.

Q. Do ICF’s need to be waterproofed when used below grade?
A. Yes, waterproofing is required as it is with any other material used below grade.

Q. How are utilities installed in an ICF concrete home?
A. Utility connections to the building should be identified prior to the concrete pour since conduits for these connections are placed through the wall so the utility can enter. Once the concrete is poured, and cured, channels for plumbing and electric are cut directly in the foam panels of the ICF’s and the lines are inserted directly into the panels and covered with drywall.

Q. Are ICF’s code approved?
A. Yes. Every major code in North America has approved ICF’s. They are also listed in the International Residential Code as a prescriptive method of building. They can also be built to commercial design specification using the International Building Code.

Q. Can traditional window and door bucks be used with ICF’s?
A. Yes. Wooden or vinyl bucks are built and incorporated into the wall as it is being stacked prior to pouring the concrete. After the concrete has cured, windows and doors are installed as usual. In addition to traditional wood and vinyl bucks, new EPS buck technology is currently available and lends itself well to ICF/concrete construction providing the same benefits as do ICF’s in the wall assembly.

Q. Are ICF’s considered a “green” building material and do they contribute to LEED?
A. ICF’s are considered a “green” building material since they help a building achieve significant energy efficiency. They also contribute to LEEDv4 in six of the seven categories contributing as many as 37 points out of a total of 110.

Q. How do I fasten the interior elements of the the structure to the walls?
A. Molded in the ICF form is a plastic fastener termed a “web.” The web functions just like a 2”x4” or 2”x6” wood or steel stud when it comes to fastening cabinets and interior finishes to the wall. The plastic is a virgin polypropylene that has superior “pull-out” strength and so when screws are placed in them, they will perform the same function as will screws into studs.

Q. How do I locate a plastic “web” if it is behind a wall covering?
A. Use of a magnetic stud finder enables locating the screws used to fasten the wall covering to the “webs” in the wall and so will provide the location of the “webs” themselves. Using this tool will allow the easy hanging of items on interior walls.

Q. Isn’t ICF construction more expensive than traditional construction methods?
A. The real answer is “it depends.” It depends on where a building is being built. It depends on the cost of materials in a specific location. It depends on the availability of experienced installers. It depends on statewide and jurisdictional building codes. However, although ICF construction may be the same or in some cases even less cost than traditional methods a minimal price differential should be considered in light of the time in which a building will be inhabited compared to not only the energy, owners insurance and maintenance costs saved, but in light of the other benefits of concrete construction simply not available from traditional construction such as comfort, quiet, health and safety.

Q. Builders tell me they can build with wood frame construction that will deliver the same energy efficiency as an ICF/concrete building . Is this true?
A. The answer is somewhat complicated and one should ask good questions or involve a third party that is very knowledgeable about energy efficiency in building design before blindly accepting what a designer or builder says. Building an energy efficient structure is complex. There are many approaches to the use of materials in certain configurations that would appear to match the energy efficiency of ICF’s and concrete as the building envelope. But many builders simply do not fully understand the finer points of thermal bridging, air infiltration or the effect of moisture on common types of insulation let alone the effect of poor execution of energy efficient design during the building process as a result of third party trade contractors. For example, calculating thermal performance strictly with R-values is common, but not an accurate way to understand thermal performance.

Using “U-value” as prescribed in the 2015 International Building Code indicates that while it is possible to achieve comparable energy efficiency in wood frame systems, the effects of thermal bridging and discontinuous insulation can severely degrade the thermal performance of standard designs by as much as 65%.

Q. Aren’t ICF’s only used below grade?
A. This is a common misperception. ICF’s are ideal for foundations and lower level living spaces. However, they are just as ideal for above grade exterior envelopes and actually are as easy or easier to construct as traditional wood frame wall assemblies.

Q. Do exposed ICF walls in lower level living spaces meet fire codes?
A. To meet a thermal barrier requirement, United States code requires a 15 minute fire rated covering be applied to unfinished walls in habitable spaces. This can be accomplished over an ICF wall with the addition of a ½” drywall or any other finish that meets this 15 minute requirement.

Q. I’ve heard that termites are a problem for ICF’s?
A. The expanded polystyrene in the ICF panels is not a food source for termites or any other insects or rodents for that matter. Termites do not eat expanded polystyrene. They can however burrow through the panels (not the concrete) up to a connection within the structure that allows them to find wood to eat. Termites are not prevalent in the northern climates like Minnesota, Wisconsin, parts of Iowa and Michigan and so are typically not an issue there..

They are somewhat more prevalent in Illinois, Indiana, Ohio and Kentucky but again have not proven to be an issue for ICF’s.

Termites are an issue in the Southeastern United States.Recommendations for protecting a structure from termites include removing the conducive conditions termites need to survive, i.e. eliminate moisture around the foundation and remove any wood around the foundation that may make contact with the soil. An 18” gap between the soil and wood portions of a building are ideal.

Treat the soil around the foundation with termite protective chemicals. Sodium borate is a substance that makes building materials termite proof and it can be used with ICF’s and wood building materials to deter termites.

Q. Are there any insurance benefits as a result of building with ICF’s?
A. A CELBLOX/concrete building may qualify for lower insurance rates since the walls are considered by insurance companies to be a “superior” type of construction. CELBLOX/concrete walls have a 2 to 4 hour fire rating, can withstand winds of up to 250 miles per hour and resist flying debris hurled at them at speeds of up to 100 miles per hour. CELBLOX ICF’s are made from flame retardant expanded polystyrene which is fire resistant and does not burn, it is non-toxic and has a flame spread of zero. The concrete within a CELBLOX wall assembly is non-flammable and as a result it also provides a barrier against flame infiltration from the outside.