The waffle-grid ICF wall system is a concrete wall composed of closely spaced vertical (maximum 12 inches on center) and horizontal (maximum 16 inches on center) concrete members with concrete webs between the members. A flat ICF wall system is a solid concrete wall of uniform thickness with sheets of insulation forming the interior and exterior surfaces of the system. Figure 1. ICFs provide continuous wall insulation from the roof to footing with very little thermal bridging the ICFs in this home in Las Vegas provide R-40 wall insulation (Source: Department of Energy).įigure 2. The ICF consists of wall forms made of rigid foam blocks or panels that are held in place with plastic or metal spacers and reinforced with metal rebar (Source: National Research Council Canada).Ĭommon types of ICF walls are shown in Figures 3 and 4. Some ICF walls consist of two layers of concrete sandwiching a central layer of foam. A few products are made with recycled foam or wood. Some ICF products use extruded polystyrene (XPS) foam, which is stronger but more costly. The foam is typically expanded polystyrene (EPS). Some ICFs come with plastic nailing strips embedded in their exterior surfaces. Steel rebar is added to the cavities for additional strength (Figure 2). The blocks are stacked like bricks to create the wall forms for the concrete.
![concrete foam blocks concrete foam blocks](https://i.ytimg.com/vi/2OUgqlzDIrw/maxresdefault.jpg)
The ties hold the foam panels 6 or 8 inches apart during the pour and remain in place afterward. Foam blocks are typically comprised of two 2-inch-thick, 16 by 48-inch rectangles of foam that are connected by plastic, metal, or foam ties. The foam forms stay in place, providing permanent insulating foam layers on the interior and exterior of the wall. ICFs are typically made of pre-molded blocks or panels of rigid foam, which are assembled on site to create wall forms into which concrete is poured (Figure 1).
![concrete foam blocks concrete foam blocks](https://nexcembuild.com/wp-content/uploads/2018/06/newimage-1080x675.png)
ICF walls have almost no thermal bridging in the wall itself and, with proper design details, thermal bridging can be almost eliminated at the rim joist as well ( Petrie et al. Studies comparing ICFs with stick-frame construction have shown that in otherwise identical homes, the ICF houses had a 9% better whole-wall R-value and were 10% more airtight ( Christian 1996). Insulated concrete form (ICF) construction combines concrete and rigid foam for walls that are thick, sturdy, and continuously insulated.