Insulating Concrete Form Systems (ICFs)--In-Depth Analysis

Insulating concrete forms (ICFs) are rigid plastic foam forms that are filled with reinforced concrete to create structural walls. They hold concrete in place during curing and remain in place afterwards to provide thermal insulation. ICFs are used to make structural concrete walls, and can be used to make either foundation or above-grade walls. The forms are typically made from pure foam-plastic insulation but may also be made from a composite of cement and foam insulation or a composite of cement and processed wood. The foam is typically either expanded polystyrene (EPS) or extruded polystyrene (XPS) and occasionally polyurethane. Forms come in three basic form-types: blocks, planks, and panels. Blocks are molded, hollow foam blocks that are stacked, much like Legos®. Plank and panel types use flat sheets (typically) of foam held together with plastic or metal ties, with panels using larger sheets of foam, similar to metal or plywood formwork. The resulting shape of the concrete, explained in more detail later, will be one of several shapes: flat, waffle- or screen-grid, or post-and-beam.

As with any product, ICFs have their advantages and disadvantages. Although they can be more expensive than other residential wall types, and there is much debate over their use below grade because of termites, ICFs appeal to builders and homeowners due to the many possible advantages of ICFs. Advantages over conventional construction include a reduction in the number of trade contractors required, strength, thermal efficiency, reduction in through-the-wall sound transmission, and the ease of construction. This report presents these issues and more in further detail, including comments from builders and homeowners familiar with ICFs.

The use of ICFs in the United States appears to be growing. The Portland Cement Association (PCA) reports that in 1994, 0.1% of all new homes used ICFs in above-grade walls (about 1100 new homes). That number rose to 0.2% in 1995 and 0.7% in 1996. The PCA reports that, based on ICF shipment data and a National Association of Home Builders (NAHB) survey, the number of houses built using ICFs increased to 10,344 in 1997, compared to 7,336 in 1996.

There are currently more than 35 manufacturers of ICF systems. Many manufacturers belong to the Insulating Concrete Form Association (ICFA), an industry trade group.