Insulated concrete forms (ICFs) are typically purchased from a local building supplier. Currently, the purchase price of a regular 16” x 48” styrofoam ICF block is in the $21-$24 range, depending on what region/country it is purchased in. This translates to about $4.00 – $4.50 per SF of wall area. With concrete and rebar, material costs will be approx $8.00 – $10.00 per SF (depending on the design and location). But Styrofoam is not the only option in Insulated concrete forms. There are materials like Nexcem cement bonded wood fiber that offer a better ICF solution. Building with a non-EPS ICF like Nexcem costs about $8.00 per SF for the block, uses 25% less concrete and approximately the same amount of steel. This translates to an extra $3.00 – $4.00 per SF of wall area. At first glance, this seems like a large premium (double the price) to avoid the polystyrene, but in fact it works out to be a fairly reasonable premium for a much better product. Let’s take an example of a home that has a 2500 SF footprint (say 50ft x 50ft). This would mean there is 200 linear ft of wall. if the walls were 9ft high and had the normal 15% window area, you would need 1530 SF of ICF per floor. At a $4.00 premium, The extra cost of building with a product like Nexcem would be $6000 per floor. Fairly reasonable for a product that:
- Doesn’t burn
- Doesn’t melt
- Not petroleum based
- No VOCs or offgasing
- Doesn’t dent (Impact resistant)
- Has better thermal performance (R-28+)
- Provides a regulated humidity level (breathable / hygroscopic)
- You can leave it exposed on the interior
- No fire retardants
- Termite and insect proof
So, how much will it cost to build with ICFs compared to regular construction? Every home, designer, builder and homeowner is different, and there are many variables in play that make it difficult to arrive at a general rule of thumb to accurately answer that question. If you ask most builders, they don’t actually know the cost of their perimeter walls separated from the rest of the build. Nonetheless, here is an example that illustrates general ICF construction pricing given typical lumber prices and prevailing interest rates:
- Below grade, ie for your basement, the overall cost of an ICF-constructed basement should be similar to a conventionally constructed one that is framed and insulated to R-20 or better.
- Above grade, walls built with ICFs can cost in the range of $5-$8/sq. ft. more than ordinary 2 x 6 stick-framed walls. Again for a typical 2500 square foot plan, that would translate to an extra $7000 – $12,000 per floor