According to several studies, ICF construction costs are more expensive than those of wood frame construction (5 to 10%...) and very similar to those of pre-cast concrete block or poured-in-place concrete construction.
Anyway we should consider other factors. ICF construction costs depend on the... Insulated Concrete Forms (ICFs): ICFs are prefabricated products for home construction; typically, they consist of hollow blocks or panels made of plastic foam, designed to be part of the walls and to be filled with concrete.
1) exact type and features of the ICF products (standard vs. non-standard);
2) thickness of the insulation layers;
3) width of the cavity;
4) climate zone and...
ICF web & Prices
The ICF web (the stuff that connects the two sides of the forms) has a marginal impact on prices. Just choose a non-conductive web: steel is a bad choice from a thermal standpoint.
Thickness of ICF Insulating Layers & Prices
ICFs can be made of styrofoam, rockwool, cement-bonded recycled with wood and other insulation materials. But the most inexpensive and typical ICFs are made with EPS (expanded polystyrene).
As expected, ICFs with thicker layers of insulating materials can be significantly more expensive.
Some of the most environmentally-friendly ICFs - products made with cement-bonded wood fibers, for instance - are also more expensive (besides having a smaller R-value (insulation value)).
Styrofoam and mineral wool ICFs have R-values comparable to typical ICFs (made with EPS blocks) but slightly more expensive.
Note: the R-value (insulation value) provided by Insulated Concrete Forms falls short of the recommended for energy-efficient buildings, in cold climates. Increasing that value by gluing additional rigid foam to the forms will increase the final costs.
cavity width and ICF prices
ICF walls involving a larger cavity, that is, with a thicker “layer” of concrete – often strengthened with reinforced steel – are stronger and will have a better seismic- and wind- resistance. But they will cost a bit more.
The type of cavity (flat, waffle...) also matters.
Other features With impact on prices
Interlocking grids: ICF interlocking grid systems are becoming standard; they can speed the construction time; forms that only stack together – instead of interlocking - aren't so easy to work with and are not necessarily cheaper.
“Custom” ICF products: Some ICF manufacturers offer panelized and large flat sheets, with special sizes, for big projects. They also have pre-cut and special assembled units. .
Environmental and health concerns: the most environmentally-friendly ICF products are made with recycled expanded polystyrene (styrofoam), mineral fibers (rock-wool) and cement-bonded wood fibers.
When comparing costs, consider:
- prices of standard ICF units: they vary, but expect prices between $1.75-$3.5 per square foot (the prices do not include labor costs, reinforcement, concrete pouring and finishes);
Expect ICF prices between $2 and $3.5 per square foot. prices of proprietary ICFs are can be significantly higher.
- labor costs: siding, drywall, plumbing or carpentry contractors unfamilar with ICF construction may charge you more.
ICF vs. Wood-frame Case Study
According to a study mentioned by PCA (Portland Cement Association), carried out in Maryland, for three homes built side by side by the same crew and builders, ICF construction adds 3 percent to the cost of the house, when compared with wood framing. See, PCA study.