Insulating Concrete Forms2008Page1Insulating Concrete FormsInsulating Concrete Forms (ICFs) are poured-in-place reinforced concrete buildingsystems comprised of hollow blocks, panels, or planks made of rigid foam (typicallypolystyrene). The forms are erected and filled with concrete and reinforcing rods to formthe structure and to insulate of exterior walls. ICFs are growing rapidly in popularitybecause they are cost-competitive with wood-frame construction, easy to learn to use, andenvironmentally friendly. Yet, they deliver a high quality building that is more energyefficient, comfortable, durable, stronger, quieter, and more resistant to natural elements.ICFs originally were used mostly for basements of homes but are currently usedprimarily for wall construction, although several manufacturers are designing additionalforming components that will allow the construction of attached concrete floors at thesame time.Types of ICFsThere are over 45 manufacturers of ICFs in the United States and many of thesecompanies are members of the Insulating Concrete Forms Association (ICFA). The ICFAweb site () and can be contacted for information on the product as well asa directory of its member ICF producers.Although there are a number of different manufacturers, there are only three basic typesof ICFs based on the shape of the cavity that is filled with concrete:flat, grid, and post-and-beam.Regardless of the shape of the internal concrete, there are two ways of connecting thefront and back of the form. In one arrangement, plastic or metal cross ties are used toconnect the two sides of the form. In some of the grid-pattern forms, a foam bridgeconnects the front and back of the form. The metal or plastic cross ties do not affect theshape of the concrete, but the foam bridges cause breaks in the concrete every foot or so.The following figure shows plastic cross ties and, second from the left, is a solid foambridge connection.
Insulating Concrete Forms2008Page2The third difference among the various ICFs is the type of fastening surface provided toattach exterior or interior finishes. This fastening surface is another material imbedded inthe foam into which screws or nails can be driven to hold the finish material. In thosesystems that employ a plastic or metal crosstie, the fastening surface is simply theexposed end of the crosstie. In those systems that do not use the metal or plastic crossties, the installation crew must perform extra steps to connect wallboard, trim, exteriorsiding, etc. to the walls. Shown in the following figure are wooden furring strips thathave been imbedded in the some foam panels as a means of providing a fastening surface.Foam Cutting ToolAn important tool that should be acquired to work with the ICF forms is ahot knifewithan assortment of blades and attachments. The hot knife is used to excavate the foam inorder to install electric cable and plumbing lines as well as to install fastening surfaces.