Regardless of which system is employed, the resulting walls combine the thermal mass and strength of concrete with the energy-saving benefits of integral insulation on both sides. Depending on the interior width of the cell (for most homes, either 4 or 6 inches, which combined with 2?1/2-inch-thick foam on either side create 9- to 11-inch-thick walls before finishes are applied), ICF walls can achieve finished-wall R-values from the low to high 20s.
As such, ICFs are often referred to, and credited, as a green building system that’s more thermally efficient than traditional wood-framed assemblies. In addition to combining structural, insulating, thermal mass, and air-sealing values in one step, ICFs also achieve integral sound abatement qualities and are less threatened by pests or moisture infiltration.
The foam used in ICFs does not produce or emit VOCs, CFCs, or HCFCs in its manufacture or application. Also, an increasing number of ICF manufacturers use recycled polystyrene in their blocks (garnered from shipping and packaging waste) and polypropylene for their ties; any foam waste generated on site from cutting or shaping the blocks or panels can be recycled—a long-standing practice for EPS users with a national recycling infrastructure in place.
Installation Best Practices
Experienced builders, suppliers, and industry experts advocate a measured, step-by-step progression toward using ICFs as a home’s primary above-grade wall system.
To avoid getting burned the first time out, Andy Lennox, vice president of marketing for Logix, advises ICF newbies to subcontract an experienced crew for a below-grade basement installation, then rely on their own crews to build an ICF basement before tackling an above-grade installation. “Taking that first step allows you to build [frame] on top of that ICF basement and appreciate how straight and true it is,” as a confidence-builder going forward, he says.
“It’s not a difficult system to learn and you can do a good job relatively quickly,” says Donn Thompson, director of Low Rise Buildings for the Portland Cement Association (PCA) in Skokie, Ill., which promotes ICFs among other concrete building applications. “But an experienced firm can help with some of the tricks and tips so you can be most efficient.”
Once you’re clear of the ground, building with ICFs gets a little more complex than its use as a basement wall system. In addition, subtle differences among products and systems, including accessory components and reversible panels and blocks, also can have a big impact on product estimating procurement, labor efficiency, waste management, system performance, and their ultimate cost.
Like any well-built home, and especially one meant to achieve superior energy and environmental standards, proper and efficient use of ICFs starts with a floor plan and housing design that optimizes the system and its benefits. For instance, while the lightweight foam blocks and panels can be cut to turn radiused corners and make odd angles (some suppliers even offer smaller components for those instances), the ideal footprint only breaks at right angles and is designed on modules that match the dimensions of the blocks.