The simplicity of ICF design belies the impact of its benefits. The system’s basic components are few: a face shell of polystyrene foam, a core of reinforced
The simplicity of ICF design belies the impact of its benefits. The system’s basic components are few: a face shell of polystyrene foam, a core of reinforced concrete, and a form tie that supports the face during placement.
The face shell, which withstands the internal pressure of concrete placement, is composed of EPS expanded (beadboard, white, construction-grade version of coolers and refrigerator insulation) or XPS extruded (cellular foam like meat market trays). As foam rates R-4 per inch Û concrete has virtually none Û an ICF bearing four to five inches of foam (2 to 2.5 inches per face panel) provides a wall with R-18 to R-22 continuous insulation from footing to top plate. Additionally, the foam provides a chase for utilities, as electrical wiring and smaller-diameter plumbing runs can be routed into slots cut into the material’s thickness.
Form ties Û either (recycled) plastic or metal Û hold the faces apart and provide rigidity to the form, as well as support the rebar. The ends of the form ties, furthermore, typically extend through the foam, displaying flat ends that provide a strip for attachment of finishes like drywall.
Not exotic or unusual, design specifications for an ICF wall are typical of conventional foundations. A minor difference, however, is the aggregate size Û a recommended 38-in. maximum to allow for concrete pumping, especially in above-grade applications. A 6-in. slump and 2,500 to 4,000 psi typically characterize the 4-, 6-, 8-, or 10-in.-thick reinforced, monolithic concrete core.
Concrete placed inside an ICF actually achieves higher than normal strength, Reward Wall representatives affirm, due to ideal curing conditions, stable temperature, and slow moisture-loss rates. Concrete placed in the fully insulated forms holds moisture and heat longer, enhancing the chemical reaction that occurs as concrete hardens to produce a stronger, more durable product.
After the forms are stacked and concrete is poured, a monolithic core is produced with two continuous insulation layers. As no gaps exist in the concrete or insulation, the wall provides superior thermal performance with greatly reduced air infiltration, acoustical attenuation, improved strength, and low maintenance throughout the structure’s life cycle.